umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1 - 30 av 30
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Ambarki, Khalid
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Zarrinkoob, Laleh
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Birgander, Richard
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Blood flow of ophthalmic artery in healthy individuals determined by phase-contrast magnetic resonance imaging2013Ingår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 54, nr 4, s. 2738-2745Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: Recent development of magnetic resonance imaging (MRI) offers new possibilities to assess ocular blood flow. This prospective study evaluates the feasibility of phase-contrast MRI (PCMRI) to measure flow rate in the ophthalmic artery (OA) and establish reference values in healthy young (HY) and elderly (HE) subjects.

    METHODS: Fifty HY subjects (28 females, 21-30 years of age) and 44 HE (23 females, 64-80 years of age) were scanned on a 3-Tesla MR system. The PCMRI sequence had a spatial resolution of 0.35 mm per pixel, with the measurement plan placed perpendicularly to the OA. Mean flow rate (Qmean), resistive index (RI), and arterial volume pulsatility of OA (ΔVmax) were measured from the flow rate curve. Accuracy of PCMRI measures was investigated using a vessel-phantom mimicking the diameter and the flow rate range of the human OA.

    RESULTS: Flow rate could be assessed in 97% of the OAs. Phantom investigations showed good agreement between the reference and PCMRI measurements with an error of <7%. No statistical difference was found in Qmean between HY and HE individuals (HY: mean ± SD = 10.37 ± 4.45 mL/min; HE: 10.81 ± 5.15 mL/min, P = 0.655). The mean of ΔVmax (HY: 18.70 ± 7.24 μL; HE: 26.27 ± 12.59 μL, P < 0.001) and RI (HY: 0.62 ± 0.08; HE: 0.67 ± 0.1, P = 0.012) were significantly different between HY and HE.

    CONCLUSIONS: This study demonstrated that the flow rate of OA can be quantified using PCMRI. There was an age difference in the pulsatility parameters; however, the mean flow rate appeared independent of age. The primary difference in flow curves between HE and HY was in the relaxation phase of the systolic peak.

  • 2. Aspberg, Johan
    et al.
    Heijl, Anders
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM). Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Andersson-Geimer, Sabina
    Bengtsson, Boel
    Intraocular Pressure Lowering Effect of Latanoprost as First-line Treatment for Glaucoma2018Ingår i: Journal of glaucoma, ISSN 1057-0829, E-ISSN 1536-481X, Vol. 27, nr 11, s. 976-980Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: The purpose of this study was to assess the intraocular pressure (IOP) - reducing effect of latanoprost in treatment-naïve patients with newly detected open-angle glaucoma with no restriction of the level of untreated IOP.

    METHODS: Eighty-six patients (105 eyes) with a diagnosis of open-angle glaucoma received IOP-lowering therapy with latanoprost. The IOP reduction 1 and 3 months after initiation of treatment was recorded.

    RESULTS: Mean untreated IOP for all eyes was 26.2 mm Hg (ranging from 10 to 51 mm Hg). The mean pressure reduction was 7.9 mm Hg (28%), with equivalent average levels at 1 and 3 months. The reduction in IOP ranged from -2.3 to 25.3 mm Hg after 1 month, and from -1.3 to 33.3 mm Hg after 3 months. The pressure-lowering effect was considerably more pronounced in eyes with higher untreated IOP; the reduction increased by 0.55 mm Hg per mm Hg higher untreated IOP. Four eyes, with untreated IOP within statistically normal limits, had no or negative IOP-reduction. A regression model predicted that IOP reduction ended at untreated IOP≤16 mm Hg. Multiple regression analysis showed that an additional IOP-lowering effect of 1.28 mm Hg was achieved in eyes with pseudoexfoliation glaucoma.

    CONCLUSIONS: To the best of our knowledge, this paper is the first to report the IOP-reducing effect of latanoprost treatment at all untreated IOP levels in newly detected glaucoma patients. The effect was proportional to the untreated IOP at all levels above 16 mm Hg and better at higher untreated IOP levels, also in relative terms. Our results further confirm the indication of latanoprost as a first-line therapy for glaucoma.

  • 3. Bengtsson, Boel
    et al.
    Heijl, Anders
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Andersson-Geimer, Sabina
    Aspberg, Johan
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    The Glaucoma Intensive Treatment Study (GITS), a randomized clinical trial: design, methodology and baseline data2018Ingår i: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 96, nr 6, s. 557-566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: The primary objective of the ongoing Glaucoma Intensive Treatment Study (GITS) is to evaluate the effectiveness of immediate intensive treatment in comparison with the commonly recommended stepped regimen on the predicted visual field. The two treatment arms are also being compared regarding quality of life (QoL), intraocular pressure (IOP) reduction, frequency of reported side‐effects, adverse events and adherence to prescribed treatment.

    Design: A randomized, two‐centre, prospective open‐labelled treatment trial for open‐angle glaucoma.

    Participants: Individuals aged 40–78 years with previously untreated and newly diagnosed glaucoma with early to moderate visual field loss were eligible.

    Methods: Patients were randomized to initial treatment either using drug monotherapy in accordance with common glaucoma guidelines or using a more intensive approach including eyedrops containing drugs from three different classes combined with 360° laser trabeculoplasty. The patients are to be followed for 5 years at visits including standard automated perimetry, optical coherence tomography (OPT) and tonometry. Change of treatment is allowed and decided upon jointly with the patient as in conventional glaucoma management.Main outcome: The estimated predicted preserved visual field and QoL at end of expected lifetime.

    Results: A total of 242 patients, 45% females, mean age 68 years, were randomized. The median untreated IOP was 24 mm Hg, and the median visual field index (VFI), indicating the percentage of a full field, was 92%.

    Conclusion: Glaucoma Intensive Treatment Study is a clinical trial in which two groups of patients randomized to different initial intensities of IOP‐reducing treatment are being compared with regard to rate of visual field progression and prediction of serious glaucomatous visual field loss at estimated at end of life.

  • 4.
    Eklund, Anders
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Farmakologi.
    Holmlund, Petter
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Ambarki, Khalid
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Koskinen, Lars-Owe D.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Farmakologi.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    The Pressure Difference between Eye and Brain Changes with Posture2016Ingår i: Annals of Neurology, ISSN 0364-5134, E-ISSN 1531-8249, Vol. 80, nr 2, s. 269-276Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective: The discovery of a posture-dependent effect on the difference between intraocular pressure (IOP) and intracranial pressure (ICP) at the level of lamina cribrosa could have important implications for understanding glaucoma and idiopathic intracranial hypertension and could help explain visual impairments in astronauts exposed to microgravity. The aim of this study was to determine the postural influence on the difference between simultaneously measured ICP and IOP.

    Methods: Eleven healthy adult volunteers (age = 46 ± 10 years) were investigated with simultaneous ICP, assessed through lumbar puncture, and IOP measurements when supine, sitting, and in 9° head-down tilt (HDT). The trans–lamina cribrosa pressure difference (TLCPD) was calculated as the difference between the IOP and ICP. To estimate the pressures at the lamina cribrosa, geometrical distances were estimated from magnetic resonance imaging and used to adjust for hydrostatic effects.

    Results: The TLCPD (in millimeters of mercury) between IOP and ICP was 12.3 ± 2.2 for supine, 19.8 ± 4.6 for sitting, and 6.6 ± 2.5 for HDT. The expected 24-hour average TLCPD on earth—assuming 8 hours supine and 16 hours upright—was estimated to be 17.3mmHg. By removing the hydrostatic effects on pressure, a corresponding 24-hour average TLCPD in microgravity environment was simulated to be 6.7mmHg.

    Interpretation: We provide a possible physiological explanation for how microgravity can cause symptoms similar to those seen in patients with elevated ICP. The observed posture dependency of TLCPD also implies that assessment of the difference between IOP and ICP in upright position may offer new understanding of the pathophysiology of idiopathic intracranial hypertension and glaucoma. 

  • 5. Gudmundsdottir, Birna S.
    et al.
    Petursdottir, Dyrleif
    Asgrimsdottir, Gudrun M.
    Gottfredsdottir, Maria S.
    Hardarson, Sveinn H.
    Johannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Kurkov, Sergey V.
    Jansook, Phatsawee
    Loftsson, Thorsteinn
    Stefansson, Einar
    gamma-Cyclodextrin Nanoparticle Eye Drops with Dorzolamide: Effect on Intraocular Pressure in Man2014Ingår i: Journal of Ocular Pharmacology and Therapeutics, ISSN 1080-7683, E-ISSN 1557-7732, Vol. 30, nr 1, s. 35-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To test a new drug delivery platform with dorzolamide γ-cyclodextrin (γCD) nanoparticle eye drops for intraocular pressure (IOP) control and safety and compare with Trusopt.® Methods: Self-aggregating γCD nanoparticle eye drops containing 3% dorzolamide were given once a day (QD) and compared with Trusopt given three times a day (TID) in a prospective randomized single masked crossover trial over 24 h. Seventeen subjects with IOP over 18 mmHg were recruited. IOP was measured with an Icare Tonometer Pro.® Results: There was no statistically significant difference in the IOP lowering effect of dorzolamide nanoparticle eye drops QD and Trusopt TID. At peak (4 h), the IOP reduction from baseline was 3.8±2.6 mmHg (18%, P<0.05) in the nanoparticle eye drop group and 3.1±3.7 mmHg in the Trusopt group (14%, P<0.05, P=0.97 between groups). At trough (24 h), the IOP reduction was 1.4±2.8 mmHg (6%, P>0.05) in nanoparticle eye drop group and 1.5±2.0 mmHg (7%, P>0.05) in the Trusopt group (P=0.23 between groups). Burning sensation measured on the visual analogue scale (1–100) was less from the nanoparticle eye drops (12±15) than from the Trusopt (37±30), (P=0.0038). Visual acuity and conjunctival hyperemia did not differ between the two groups. Conclusions: Dorzolamide cyclodextrin nanoparticle eye drops QD lower IOP and the effect seems comparable to Trusopt given TID. The nanoparticle eye drops are well tolerated and seem to have a better safety profile than Trusopt.

  • 6.
    Johannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ambarki, Khalid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Age-dependency of ocular parameters - a cross sectional study of young and old healthy subjects2015Ingår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, nr 7, artikel-id Meeting Abstract: 116Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Purpose: To investigate aging effect on ocular parameters inkluding intraocular pressure (IOP) measured with different tonometry methods in healthy young (HY) and elderly (HE) subjects.

    Methods: Fifty eyes of 50 HY subjects (28 females, 22-31 years of age) and 43 eyes of 43 HE subjects (22 females, 64-79 years of age) were included. IOP was measured with four tonometry methods in a standardized order: Ocular Response Analyser (ORA), Dynamic Contour Tonometry (DCT), Applanation Resonance Tonometry (ART) and Goldmann Applanation Tonometry (GAT). Other measurements included axial length (AL), central corneal thickness (CCT), corneal curvature (CC), ocular pulse amplitude (OPA) and aqueous humor (aq).

    Results: The mean IOP (HY/HE; mmHg ± standard deviation) was 13.9 ± 2.7/16.4 ± 3.4 with ORA, 15.1 ± 2.1/16.3 ± 3.1 with DCT, 12.3 ± 2.0/13.7 ± 2.8 with GAT and 13.1 ± 2.2/12.1 ± 2.5 with ART. IOP was significantly higher (difference ± standard error) in HE compared to HY measured with ORA (+2.5 mmHg ± 0.6), GAT (+1.4 ± 0.5) and DCT (+1.2 ± 0.6). There was a trend towards lower IOP in HE when measured with ART (-1.0 ± 0.5, p=0.05). There was no difference between HE and HY in CCT, CC, AL or OPA.

    Conclusions: Tonometry methods are affected differently by age. IOP was measured higher in elderly people with ORA, DCT and GAT in this Scandinavian population. This effect was not seen in measurements with ART. Other ocular parameters did not differ between the age groups indicating that these measured parameters are not influenced by age in this population.

  • 7.
    Johannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ambarki, Khalid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Age-dependency of ocular parameters: a cross sectional study of young and elderly healthy subjects2015Ingår i: Graefe's Archives for Clinical and Experimental Ophthalmology, ISSN 0721-832X, E-ISSN 1435-702X, Vol. 253, nr 11, s. 1979-1983Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To investigate the effect of aging on ocular parameters, including intraocular pressure (IOP), measured with different tonometry methods in healthy young (HY) and healthy elderly (HE) subjects and to study the effect of corneal parameters on tonometry methods. In this prospective, cross-sectional study, fifty eyes of 50 HY subjects (28 females, 22-31 years of age) and 43 eyes of 43 HE subjects (22 females, 64-79) were included. IOP was measured with four tonometry methods in a standardized order: ocular response analyser (ORA), dynamic contour tonometry (DCT), applanation resonance tonometry (ART) and Goldmann applanation tonometry (GAT). Other measurements included axial length (AL), central corneal thickness (CCT), corneal curvature (CC), anterior chamber volume (ACV), corneal hysteresis (CH) and corneal resistance factor (CRF). The mean IOP (HY/HE; mmHg +/- standard deviation (SD)) was 12.2 +/- 2.2/14.1 +/- 3.5 with GAT. IOP was significantly higher (difference +/- standard error) in HE compared to HY measured with an ORA (+3.1 mmHg +/- 0.6), GAT (+1.9 +/- 0.6) and DCT (+1.6 +/- 0.6). No significant difference was found in IOP measured with ART. CH and ACV were significantly lower in HE compared to HY. There was no difference between the groups in CCT, CC, AL or CRF. No tonometry method was dependant on CCT or CC. IOP measured with an ORA and via DCT and GAT was higher in HE compared to HY Swedish subjects, while IOP measured with ART did not differ between the groups. In these homogeneous groups, tonometry methods were independent of CCT and CC.

  • 8.
    Johannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Behndig, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Effects of topical anaesthetics and repeated tonometry on intraocular pressure2014Ingår i: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 92, nr 2, s. 111-115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose:

    To investigate the effects of repeated measurements of intraocular pressure (IOP) using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) to identify mechanisms contributing to the expected IOP reduction.

    Methods:

    A prospective, single-centre study with six healthy volunteers. Consecutive repeated series (six measurements/serie/method) were made alternately on both eyes for 1 hr with oxybuprocaine/fluorescein in the right eye and tetracaine in the left. The left eye was Pentacam((R)) photographed before and repeatedly for 20 min after the IOP measurements. On a separate occasion, the same volunteers received the same amount of anaesthetic drops for 1 hr but without repeated IOP measurements.

    Results:

    A significant IOP reduction occurred with both ART and GAT in the oxybuprocaine-treated eye, -4.4 mmHg and -3.8 mmHg, respectively and with ART in the tetracaine eye, -2.1 mmHg. There was a significant difference in IOP reduction between the oxybuprocaine and tetracaine eyes with ART. There was a significant drop in anterior chamber volume (ACV) immediately after the IOP measurements, -12.6 mu l that returned to pretrial level after 2 min. After 1 hr of receiving anaesthetic eye drops (without IOP measurements), the IOP decreased significantly in the oxybuprocaine eye for both ART and GAT, -3.1 and -1.7 mmHg, respectively, but not in the tetracaine eye (p = 0.72).

    Conclusion:

    The IOP reduction cannot be explained solely by aqueous humor being pressed out of the anterior chamber. While significant IOP reduction occurred with both tetracaine and oxybuprocaine after repeated mechanical applanation, the IOP reduction was significantly greater with oxybuprocaine.

  • 9.
    Johannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Koskela, Timo
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Change in intraocular pressure measurement 2 years after myopic laser-assisted subepithelial keratectomy2012Ingår i: Journal of cataract and refractive surgery, ISSN 0886-3350, E-ISSN 1873-4502, Vol. 38, nr 9, s. 1637-1642Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To evaluate intraocular pressure (IOP) measurements 24 months after laser-assisted subepithelial keratectomy (LASEK) with 3 tonometry methods-Goldmann applanation tonometry (DCT), Pascal dynamic contour tonometry (DCT), and applanation resonance tonometry (ART)-and to compare them with measurements taken preoperatively and 3 and 6 months postoperatively. SETTING: Department of Ophthalmology, Umea University, lima Sweden. DESIGN: Prospective randomized single-center. METHODS: One randomized eye per person from myopic healthy individuals who had LASEK was included. Visual acuity, central corneal thickness (CCT), corneal curvature, and IOP were measured at all time points. Six IOP measurements were performed per method, with a 5-minute lapse between methods. RESULTS: The study evaluated 38 eyes. Two years after LASEK, dynamic ART was the only method that did not measure significantly lower IOP than before LASEK (mean -0.2 mm Hg +/- 1.6 [SD]). The greatest difference was with GAT (mean -1.9 +/- 1.7 mm Hg) followed by static ART (mean -1.2 +/- 1.6 mm Hg) and then DCT (mean -0.9 +/- 1.3 mm Hg). All methods measured significantly lower IOP at 3 months and 6 months. CONCLUSIONS: Dynamic ART, which analyses IOP measurement during indentation, showed no significant difference in measured IOP after 24 months. The convex tip of the ART device and the continuous sampling of data during corneal indentation seem to be factors in why dynamic ART was less affected by corneal properties and therefore more suitable for IOP measurement in LASEK-treated eyes, although this must be confirmed in larger trials.

  • 10.
    Johannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Shulman, Shiri
    Ruckert, Rene
    Stefansson, Einar
    In Vivo Visualization of Large Choroidal Vessels Obliteration in Geographic Atrophy2017Ingår i: Retina, ISSN 0275-004X, E-ISSN 1539-2864, Vol. 37, nr 2, s. E24-E24Artikel i tidskrift (Refereegranskat)
  • 11.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Intraocular pressure: clinical aspects and new measurement methods2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Intraocular pressure (IOP) measurement is a routine procedure and a fundament in glaucoma care. Elevated IOP is the main risk factor for glaucoma, and to date, reduction of IOP is the only possible treatment.

    In a retrospective clinical material, the prevalence of open angle glaucoma was estimated on the west coast of Iceland. IOP measurement and optic nerve head examination were used to capture glaucoma suspects, within the compulsory ophthalmological examination for the prescription of eye glasses. The results were mainly in agreement with a recent prospective study in the same region. This indicated that retrospective data, under certain conditions, may contribute with useful information on the prevalence of glaucoma. However, normal tension glaucoma is underestimated if perimetry and/or fundus photography are not included in the examination.

    Three studies focused on the measurement of IOP. Goldmann applanation tonometry (GAT) is the standard method. GAT is affected by corneal properties, e.g. central corneal thickness (CCT) and corneal curvature (CC). Refractive surgery changes these properties. This has put focus on how corneal biomechanics translate into tonometric errors and stimulated the development of new methods. As a result, Pascal

    ® Dynamic Contour Tonometry (PDCT) and Icare® rebound tonometry have been introduced. A method under development by our research group is Applanation Resonance Tonometry (ART). It is based on resonance technology and estimates IOP from continuous measurement of force and contact area.

    Comparison of PDCT, Icare and GAT in a prospective study showed that the concordance to GAT was close to the limits set by the International Standard Organization (ISO) for PDCT, while Icare was outside the limits.

    To investigate if laser-assisted subepithelial keratectomy (LASEK) affects tonometry, a study was performed where measurements with GAT, PDCT and ART were obtained before, three and six months after LASEK. The hypothesis was that PDCT and ART would be less affected by LASEK than GAT. The results showed a statistically significant reduction of measured IOP three and six months after LASEK for all tonometry methods. Change in visual acuity and IOP between three and six months suggested a prolonged postoperative process.

    A servo-controlled prototype (ART

    servo) was developed. A study was undertaken to assess the agreement of ARTservo and a further developed v

    manual prototype (ART

    manual) with GAT. The study design was in accordance with the requirements of the ISO standard for tonometers. ARTmanual fulfilled the precision requirements of the ISO standard. ARTservo did not meet all the requirements of the standard at the highest pressure levels.

    Four tonometry methods, GAT, PDCT, Icare and ART, were investigated. None of them was independent of both CCT and CC. The inconsistencies in the results emphasize the importance of study design. A meta-analysis comprising healthy eyes (IOP ≤ 21 mmHg) in the three papers, revealed age as an important confounder.

    In summary, glaucoma prevalence in Iceland was investigated and the results indicated that a retrospective approach can contribute with meaningful information. ART and PDCT had a similar agreement to GAT. ART

    manual fulfilled the precision requirements set by the ISO-standard, ARTservo and PDCT were close, while Icare was distinctly outside the limits. All tonometry methods were affected by LASEK and no method was completely independent of corneal properties.

  • 12.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Abouzeid, Hana
    Somner, John Edward Almond
    Association between rate of binocular visual field change and vision-related quality of life: novel finding or spurious association?2014Ingår i: JAMA ophthalmology, ISSN 2168-6165, E-ISSN 2168-6173, Vol. 132, nr 6, s. 784-785Artikel i tidskrift (Refereegranskat)
  • 13.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM). Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Intracranial and Intraocular Pressure at the Lamina Cribrosa: Gradient Effects2018Ingår i: Current Neurology and Neuroscience Reports, ISSN 1528-4042, E-ISSN 1534-6293, Vol. 18, nr 5, artikel-id 25Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Purpose of Review A pressure difference between the intraocular and intracranial compartments at the site of the lamina cribrosa has been hypothesized to have a pathophysiological role in several optic nerve head diseases. This paper reviews the current literature on the translamina cribrosa pressure difference (TLCPD), the associated pressure gradient, and its potential pathophysiological role, as well as the methodology to assess TLCPD. Recent Findings For normal-tension glaucoma (NTG), initial studies indicated low intracranial pressure (ICP) while recent findings indicate that a reduced ICP is not mandatory. Summary Data from studies on the elevated TLCPD as a pathophysiological factor of NTG are equivocal. From the identification of potential postural effects on the cerebrospinal fluid (CSF) communication between the intracranial and retrolaminar space, we hypothesize that the missing link could be a dysfunction of an occlusion mechanism of the optic nerve sheath around the optic nerve. In upright posture, this could cause an elevated TLCPD even with normal ICP and we suggest that this should be investigated as a pathophysiological component in NTG patients.

  • 14.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Gudmundsdóttir, Gudrún J
    Rejykjavik, Island.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Can the prevalence of open-angle glaucoma be estimated from a retrospective clinical material? A study on the west coast of Iceland.2005Ingår i: Acta Ophthalmologica Scandinavica, ISSN 1395-3907, E-ISSN 1600-0420, Vol. 83, nr 5, s. 549-553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To explore the possibility of estimating the prevalence of open-angle glaucoma (OAG) on the west coast of Iceland using a clinical retrospective material, and to compare that estimate with the results from a recent prospective Icelandic study.

    METHODS: The compulsory ophthalmological examination for the prescription of eye glasses in combination with information obtained from Statistics Iceland were used to establish the prevalence of glaucoma in Akranes and to estimate the minimum prevalence for the greater west coast area. A recent prospective study from Iceland was used as reference.

    RESULTS: In all, 79% of 1443 Akranes inhabitants aged 50 years or more had visited the eye clinic at least once between 1996 and 2001. The prevalence of OAG was 4.8% (95% CI 3.6-6.1). The minimum prevalence for the west coast was 3.8% (95% CI 3.2-4.4). The prevalence increased with age (p < 0.001). The overall prevalence was similar to that of recently published prospective data but the prevalence of normal tension glaucoma (NTG) was lower.

    CONCLUSION: The results from the two studies are similar in many respects, which indicates that retrospective data may supply meaningful information on glaucoma prevalence. Important sources of error are the selection and attendance of patients, screening methods and diagnostic criteria. If routine examination does not include fundus photography and/or perimetry, the prevalence of NTG will be underestimated.

  • 15.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Koskela, Timo
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Change in intraocular pressure measurement after myopic LASEK: a study evaluating Goldmann, Pascal and applanation resonance tonometry2012Ingår i: Journal of glaucoma, ISSN 1057-0829, E-ISSN 1536-481X, Vol. 21, nr 4, s. 255-259Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To prospectively evaluate 3 tonometry methods-the gold standard, Goldmann applanation tonometry, a new method, Pascal dynamic contour tonometry (PDCT), and a method under development, applanation resonance tonometry (ART)-with respect to intraocular pressure (IOP) measurements before, 3 and 6 months after laser-assisted subepithelial keratectomy (LASEK).

    MATERIALS AND METHODS: One randomly assigned eye of each of 53 healthy individuals, who underwent LASEK surgery for myopia was studied. Visual acuity, central corneal thickness, corneal curvature, and IOP were measured at each visit. Six IOP measurements/methods with 5 minutes pause between methods were performed.

    RESULTS: All tonometry methods measured a significantly lower IOP after LASEK correction by a mean of -3.1 diopters. The IOP reduction was largest after 6 months for Goldmann applanation tonometry (-1.7±1.8 mm Hg) followed by ARTstat (-1.2±1.5 mm Hg), PDCT (-1.1±1.6 mm Hg), and ARTdyn (-1.0±1.5 mm Hg). The reduction of IOP did not differ significantly between different methods (P=0.11). There was a significant further reduction of measured IOP for PDCT between 3 and 6 months (-0.5±1.0 mm Hg). Uncorrected visual acuity improved significantly between 3 and 6 months postoperatively from 1.32±0.28 to 1.43±0.27.

    CONCLUSIONS: All tonometry methods measured a significant, but low, reduction of IOP 3 and 6 months after LASEK. Further change in visual acuity and IOP measurements between 3 and 6 months suggest a still ongoing postoperative process.

  • 16.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Introduction and clinical evaluation of servo-controlled applanation resonance tonometry2012Ingår i: Acta Ophthalmologica Scandinavica, ISSN 1395-3907, E-ISSN 1600-0420, Vol. 90, nr 7, s. 677-682Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose:  In recent years, Applanation Resonance Tonometry (ART) has been suggested for intraocular pressure (IOP) measurements. The manual version of ART (ARTmanual) has been further developed, and to improve usability, an automatic servo-controlled prototype (ARTservo) has been proposed. The aim of this study was to assess the limits of agreement (LoA) of ARTmanual and ARTservo as compared with the reference method, Goldmann Applanation Tonometry (GAT).

    Methods:  This was a prospective single-centre study on 152 eyes from 77 subjects. It was designed according to International Standard Organization’s (ISO) requirements for tonometers (ISO 2001). Intraocular pressure was measured six times/method in a standardized order. The ART technique has two available analysis procedures: a dynamic one that measures IOP during the indentation phase and a static one that causes a Goldmann-like measurement during two seconds of full applanation. The 95% LoA was defined as ±1.96 × standard deviation of difference against GAT.

    Results:  Mean IOP for GAT was 19.1 mmHg (range: 10–37 mmHg). The 95% LoA of ARTmanual was ±4.5 mmHg for both dynamic and static analyses. The 95% LoA of ARTservo was ±5.7 mmHg for dynamic and ±4.9 mmHg for static analyses.

    Conclusions:  This study confirms that the ART methodology is feasible. The further developed ARTmanual fulfilled the ISO standard with both the dynamic and the static analysis techniques. ARTservo with static analysis was close to fulfilling the standard but failed to do so in the highest IOP range. ARTservo has the potential to greatly improve usability if further development is completed.

  • 17.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Pascal, ICare and Goldmann applanation tonometry: a comparative study2008Ingår i: Acta ophthalmologica, ISSN 1755-3768, Vol. 86, nr 6, s. 614-621Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To compare intraocular pressure (IOP) measurements by Pascal, ICare and Goldmann applanation tonometry (GAT), to evaluate the effects of central corneal thickness (CCT) and curvature on IOP measurement and to estimate the intra-observer variability.

    METHODS: A prospective, single-centre study of 150 eyes with a wide range of pressures. Six masked IOP measurements/method; corneal thickness and curvature were studied for each eye. GAT was the reference.

    RESULTS: IOPPascal and IOPICare correlated with IOPGAT (r = 0.91, 0.89). Mean ICare measurement exceeded GAT by 2 mmHg. Pascal measured higher than GAT at low IOPs and lower at high IOPs. For every 10 mmHg increase in IOP above 31 mmHg, Pascal measured 2 mmHg lower than GAT and vice versa. CCT was correlated significantly with IOPGAT (r = 0.23) and IOPICare (r = 0.43) but not with IOPPascal (P = 0.12). CCT was correlated with age. In a subgroup (>50 years), ICare and the difference between IOPGAT and IOPPascal were affected significantly by the CCT, whereas IOPGAT and IOPPascal were not. Corneal curvature was correlated significantly with IOPGAT (r = -0.27) and IOPPascal (r = -0.26) but not with IOPICare (P = 0.60). Intra-observer variability within each set of six measurements was approximately 2 mmHg, irrespective of method.

    CONCLUSION: This study showed a reasonable overall correlation and concordance between the IOP obtained with the three instruments. None of the methods were completely independent of the biomechanical properties of the cornea. ICare showed a significant dependency upon CCT, whereas GAT and Pascal showed a significant dependency on corneal curvature. All methods showed intra-observer variability, which leaves room for further improvement of methods.

  • 18.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Koskela, Timo
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Change in intraocular pressure measurement after myopic LASEK: a study evaluating Goldmann, Pascal and applanation resonance tonometryArtikel i tidskrift (Refereegranskat)
  • 19.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Behndig, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Can we trust intraocular pressure measurements in eyes with intracameral air?2014Ingår i: Graefe's Archives for Clinical and Experimental Ophthalmology, ISSN 0721-832X, E-ISSN 1435-702X, Vol. 252, nr 10, s. 1607-1610Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To evaluate the effect of intracameral air on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) in an in-vitro porcine eye model.

    METHODS: IOP was measured on thirteen freshly enucleated eyes at three reference pressures: 20, 30, and 40 mmHg. Six measurements/method were performed in a standardized order with GAT and ART respectively. Air was injected intracamerally in the same manner as during Descemet's stripping endothelial keratoplasty (DSEK) and Descemet's membrane endothelial keratoplasty (DMEK), and the measurements were repeated.

    RESULTS: Measured IOP increased significantly for both tonometry methods after air injection: 0.7 ± 2.1 mmHg for GAT and 10.6 ± 4.9 mmHg for ART. This difference was significant at each reference pressure for ART but not for GAT.

    CONCLUSIONS: Although slightly affected, this study suggests that we can trust GAT IOP-measurements in eyes with intracameral air, such as after DSEK/DMEK operations. Ultrasound-based methods such as ART should not be used.

  • 20.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik. Department of Ophthalmology, National University Hospital, University of Iceland, Reykjavik, Iceland.
    Moya-Ortega, Maria D
    Ásgrímsdóttir, Gudrun Marta
    Agnarsson, Bjarni A
    Lund, Sigrún H
    Loftsson, Thorsteinn
    Stefánsson, Einar
    Dorzolamide cyclodextrin nanoparticle suspension eye drops and trusopt in rabbit2014Ingår i: Journal of Ocular Pharmacology and Therapeutics, ISSN 1080-7683, E-ISSN 1557-7732, Vol. 30, nr 6, s. 464-467Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract Purpose: Dorzolamide nanoparticle γ-cyclodextrin eye drops may prolong the effect of dorzolamide on intraocular pressure. We test whether the nanoparticle drops have an irritating or toxic effect on the eye in an in vivo rabbit model. Methods: Eighteen pigmented rabbits were divided into 4 groups receiving dorzolamide nanoparticle γ-cyclodextrin eye drops×1/day or×2/day, Trusopt(®) (dorzolamide HCl)×3/day, and untreated controls that received no drops. The rabbits received treatment for 1 month. After sacrifice, 33 eyes and 25 Harderian glands were evaluated for histopathology in a masked way. Results: Mild inflammation was seen in 19/31 eyes and 13/23 Harderian glands. The difference in inflammation (n=eyes/n=glands)between the γ-cyclodextrin nanoparticle eye drops×1/day (n=5/5),×2/day (n=5/3), Trusopt (n=7/4), or untreated control (n=2/0) groups was nonsignificant in both eyes and glands (P=0.87 and P=0.92) Acute inflammation was seen in 1 Harderian gland that received γ-cyclodextrin nanoparticle eye drops×2/day. The difference in conjunctival injection between the groups was nonsignificant (P=0.30). Conclusions: Dorzolamide γ-cyclodextrin nanoparticle eye drops are no more locally toxic or irritating to the eye than Trusopt.

  • 21.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik. Department of Ophthalmology, University of Iceland, National University Hospital, IS 101 Reykjavík, Iceland.
    Moya-Ortega, Maria D
    Faculty of Pharmaceutical Sciences, University of Iceland, Reykjavik, Iceland and Oculis Ehf., Reykjavik, Iceland.
    Ásgrímsdóttir, Gudrún Marta
    Oculis Ehf., Reykjavik, Iceland .
    Lund, Sigrún H
    Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
    Thorsteinsdóttir, Margrét
    Loftsson, Thorsteinn
    Faculty of Pharmaceutical Sciences, University of Iceland, Reykjavik, Iceland.
    Stefánsson, Einar
    Department of Ophthalmology, University of Iceland, National University Hospital, IS 101 Reykjavík, Iceland .
    Kinetics of γ-cyclodextrin nanoparticle suspension eye drops in tear fluid2014Ingår i: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 92, nr 6, s. 550-556Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: We have developed nanoparticle γ-cyclodextrin dexamethasone (DexNP) and dorzolamide (DorzNP) eye drops that provide sustained high drug concentrations on the eye surface. To test these characteristics, we measured dexamethasone and dorzolamide levels in tear fluid in humans following eye drop administration.

    METHODS: Concentration of dexamethasone was measured by mass spectrometry. One drop of DexNP was instilled into one eye. Tear fluid was sampled with microcapillary pipettes at seven time-points after drop instillation. Control eyes received Maxidex(®) (dexamethasone). The same procedure was performed for dorzolamide with DorzNP and Trusopt(®) .

    RESULTS: Six subjects were included in each group. The peak concentration (μg/ml ± standard deviation) of dexamethasone for DexNP eye drops (636.6 ± 399.1) was up to 19-fold higher than with Maxidex(®) (39.3 ± 18.9) (p < 0.001). At 4 hr, DexNP was still 10 times higher than Maxidex(®) . In addition, DexNP resulted in about 30-fold higher concentration of dissolved dexamethasone in the tear fluid of extended time period allowing more drug to partition into the eye tissue. The overall concentration of dorzolamide was about 50% higher for DorzNP (59.5 ± 76.9) than Trusopt(®) (40.0 ± 76.7) (p < 0.05).

    CONCLUSION: The results indicate high and extended concentration of dissolved dexamethasone with DexNP, which can explain the greater and longer lasting effect of dexamethasone in the cyclodextrin nanoparticle drug delivery platform. Dexamethasone seems to fit the cyclodextrin nanoparticle suspension drug delivery platform with longer duration and higher concentrations in tear fluid than available commercial drops, while dorzolamide is less suitable.

  • 22.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik. Department of ophthalmology, Faculty of medicine, University of Iceland, Reykjavik, Iceland.
    Stefánsson, Einar
    Loftsson, Thorsteinn
    Microspheres and Nanotechnology for Drug Delivery2016Ingår i: Developments in ophthalmology, ISSN 1662-2790, Vol. 55, s. 93-103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ocular drug delivery to the posterior segment of the eye can be accomplished by invasive drug injections into different tissues of the eye and noninvasive topical treatment. Invasive treatment involves the risks of surgical trauma and infection, and conventional topical treatments are ineffective in delivering drugs to the posterior segment of the eye. In recent years, nanotechnology has become an ever-increasing part of ocular drug delivery. In the following, we briefly review microspheres and nanotechnology for drug delivery to the eye, including different forms of nanotechnology such as nanoparticles, microparticles, liposomes, microemulsions and micromachines. The permeation barriers and anatomical considerations linked to ocular drug delivery are discussed and a theoretical overview on drug delivery through biological membranes is given. Finally, in vitro, in vivo and human studies of x03B3;-cyclodextrin nanoparticle eyedrop suspensions are discussed as an example of nanotechnology used for drug delivery to the eye.

  • 23.
    Kristiansen, Martin
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Ambarki, Khalid
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Blood flow rate of ophthalmic artery in patients with normal tension glaucoma and healthy controls2018Ingår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, nr 9Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Purpose: To determine the blood flow rate of the ophthalmic artery (OA) in patients with Normal Tension Glaucoma (NTG) compared to age-matched healthy controls using phase-contrast magnetic resonance imaging (PCMRI).

    Methods: Seventeen patients with treated NTG (11 female; mean age: 70±9 years) and 16 age-matched healthy controls (10 female; mean age: 71±9 years) underwent PCMRI using a 3-Tesla scanner as well as ophthalmological examinations including visual acuity, Goldmann Applanation Tonometry, Humphrey perimetry and fundoscopy. Ophthalmic blood flow was acquired using a 2D PCMRI sequence set to a spatial resolution of 0.35mm/pixel. Mean flow rate and cross-sectional area was calculated using Segment Software. The eye with the most severe glaucomatous damage classified by visual field index (VFI) was chosen for comparison. The primary outcome was blood flow rate of OA.

    Results: The mean VFI was 41% ± 26 (mean±SD) for the worse NTG eyes. The intraocular pressure was 13.6±2.6 mmHg for NTG eyes and 13.8±2.1 mmHg for control eyes. The blood flow rate in the NTG group was 9.6±3.7 ml/min compared to 11.8±5.5 ml/min in the control group. The area was 1.7±0.3 mm2 and 2.0±0.6 mm2 respectively. No statistical significance was found between NTG and the control group regarding blood flow rate (p=0.07) or OA area (p=0.12).

    Conclusions: Despite OA being an anastomosis between the intracranial and extracranial circulation, possibly generating an eye unrelated variability in blood flow, we found a trend level reduction of approximately 2 ml/min in NTG. The finding warrants blood flow rate analysis of smaller arteries specifically supplying the eye, e.g. the central retinal artery.

  • 24.
    Linden, Christina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Heijl, Anders
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik. Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM).
    Aspberg, Johan
    Andersson Geimer, Sabina
    Bengtsson, Boel
    Initial intraocular pressure reduction by mono‐ versus multi‐therapy in patients with open‐angle glaucoma: results from the Glaucoma Intensive Treatment Study2018Ingår i: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 96, nr 6, s. 567-572Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To study newly diagnosed glaucoma patients given mono‐ or multi‐therapy regarding differences in initial intraocular pressure (IOP) reduction, target IOP levels reached and influence of untreated baseline IOP on IOP reduction.

    Methods: Patients newly diagnosed with manifest primary open‐angle glaucoma and included in the Glaucoma Intensive Treatment Study (GITS) were randomized to immediate intensive treatment with any of three different IOP‐lowering substances supplied in two bottles plus 360° laser trabeculoplasty or to conventional stepwise treatment starting with a single‐drug. Intraocular pressure reduction was analysed 1 month after initiation of treatment.

    Results: One hundred eighteen patients (143 eyes) received mono‐therapy and 122 patients (152 eyes) multi‐therapy. Median baseline IOP was 24.0 (min: 9.7, max: 56.0) mmHg in mono‐therapy eyes and 24.0 (min: 12.3, max: 48.5) mmHg in multi‐therapy eyes (p = 0.56). After 1 month in the two groups, respectively, values for median IOP reduction were 6.3 (range: −5.3–31.0) and 11.0 (range: 0.7–34.5) mmHg, and for mean relative decline 26.8 (range: −32.0–55.4) and 46.0 (range: 4.6–81.6) % (p = 0.000). A larger proportion of the multi‐therapy patients reached each target IOP level (p = 0.000). The higher the baseline IOP, the larger the observed pressure reduction, considering both absolute and relative figures. The effect was more pronounced in eyes with multi‐therapy than in those with mono‐therapy (p = 0.000). For every mmHg higher IOP at baseline, the IOP was reduced by an additional 0.56 (mono‐therapy) or 0.84 (multi‐therapy) mmHg.

    Conclusion: Intensive treatment led to considerably greater IOP reduction than mono‐therapy. Among patients with IOP ≥30 mmHg at diagnosis an IOP of <16 was reached in 2/3 of those with multi‐therapy but in none with mono‐therapy. The IOP reduction was highly dependent on the untreated IOP level.

  • 25.
    Lindén, Christina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Östlund, Fanny
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Normal-Tension Glaucoma Has Normal Intracranial Pressure: A Prospective Study of Intracranial Pressure and Intraocular Pressure in Different Body Positions2018Ingår i: Ophthalmology (Rochester, Minn.), ISSN 0161-6420, E-ISSN 1549-4713, Vol. 125, nr 3, s. 361-368Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To test the hypothesis that normal-tension glaucoma (NTG) is caused by an increased pressure difference across the lamina cribrosa (LC) related to a low intracranial pressure (ICP).

    DESIGN: Prospective case-control study.

    PARTICIPANTS: Thirteen NTG patients (9 women; median 71 [range: 56-83] years) were recruited for investigation with the same protocol as 11 healthy volunteers (8 women; 47 [30-59] years). A larger control group (n = 51; 30 women; 68 [30-81] years) was used only for ICP comparison in supine position.

    METHODS: ICP and intraocular pressure (IOP) were simultaneously measured in supine, sitting, and 9° head-down tilt (HDT) positions. Trans-lamina cribrosa pressure difference (TLCPD) was calculated using ICP and IOP together with geometric distances estimated from magnetic resonance imaging to adjust for hydrostatic effects.

    MAIN OUTCOME MEASURES: ICP, IOP, and TLCPD in different body positions.

    RESULTS: Between NTG patients and healthy volunteers, there were no differences in ICP, IOP, or TLCPD in supine, sitting, or HDT (P ≥ 0.11), except for IOP in HDT (P = 0.04). There was no correlation between visual field defect and TLCPD, IOP, or ICP and in any body position (P ≥ 0.39). Mean ICP in supine was 10.3 mmHg (SD = 2.7) in the NTG group (n = 13) and 11.3 (2.2) mmHg in the larger control group (n = 51) (P = 0.24).

    CONCLUSIONS: There was no evidence of reduced ICP in NTG patients as compared with healthy controls, either in supine or in upright position. Consequently, the hypothesis that NTG is caused by an elevated TLCPD from low ICP was not supported.

  • 26.
    Lindén, Christina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Östlund, Fanny
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) REPLY2018Ingår i: Ophthalmology (Rochester, Minn.), ISSN 0161-6420, E-ISSN 1549-4713, Vol. 125, nr 6, s. e43-e44Artikel i tidskrift (Refereegranskat)
  • 27.
    Lindén, Christina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin. Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Östlund, Fanny
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Re: Linden et al.: Normal-tension glaucoma has normal intracranial pressure: a prospective study of intracranial pressure and intraocular pressure in different body positions (Ophthalmology. 2018;125:361-368) REPLY2018Ingår i: Ophthalmology (Rochester, Minn.), ISSN 0161-6420, E-ISSN 1549-4713, Vol. 125, nr 10, s. E74-E75Artikel i tidskrift (Refereegranskat)
  • 28. Ohira, Akihiro
    et al.
    Hara, Katsunori
    Johannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Tanito, Masaki
    Asgrimsdottir, Gudrun Marta
    Lund, Sigrun H.
    Loftsson, Thorsteinn
    Stefansson, Einar
    Topical dexamethasone -cyclodextrin nanoparticle eye drops increase visual acuity and decrease macular thickness in diabetic macular oedema2015Ingår i: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 93, nr 7, s. 610-615Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PurposeTo compare in a randomized, controlled trial topical 1.5% dexamethasone -cyclodextrin nanoparticle eye drops (DexNP) with posterior subtenon injection of triamcinolone acetonide in diabetic macular oedema (DME). MethodsIn this prospective, randomized, controlled trial, 22 eyes of 22 consecutive patients with DME were randomized to (i) topical treatment with DexNP x3/day (4weeks), x2/day (4weeks) and x1/day (4weeks) or (ii) one posterior subtenon injection of 20mg triamcinolone acetonide. Study visits were at baseline and 4, 8, 12 and 16weeks. ResultsThe logMAR (Snellen) visual acuity (meanSD) improved significantly with DexNP from 0.41 +/- 0.3 (Snellen 0.39) to 0.32 +/- 0.25 (0.48) and 0.30 +/- 0.26 (0.50) at 4 and 8weeks, respectively. One-third of the DexNP group improved more than 0.3 logMAR units. For triamcinolone, logMAR changed significantly from 0.42 +/- 0.28 (0.38) at baseline to 0.32 +/- 0.29 (0.48) at 4w and 0.33 +/- 0.37 (0.47) at 12w. The central macular thickness (CMT) decreased significantly with DexNP from 483 +/- 141m to 384 +/- 142m at 4w and 342 +/- 114m at 8w. For triamcinolone, CMT decreased significantly at all time-points: 494 +/- 94m, 388 +/- 120, 388 +/- 145, 390 +/- 136 and 411 +/- 104m at 0, 4, 8, 12 and 16weeks, respectively. There was a modest increase in intraocular pressure (IOP) at all time-points with DexNP while no increase was seen with triamcinolone. Serum cortisol was affected by both treatments. ConclusionTopical DexNP significantly improve visual acuity and decrease macular thickness in patients with DME. The effect is similar to that from subtenon triamcinolone. A modest increase in IOP was seen with the nanoparticle eye drops, but IOP normalized after the discontinuation of treatment.

  • 29.
    Ohira, Akihiro
    et al.
    Izumo, Japan.
    Hara, Katsunori
    Izumo, Japan.
    Johannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Tanito, Masaki
    Izumo, Japan.
    Asgrimsdottir, Gudrun Marta
    Reykjavik, Iceland.
    Lund, Sigrun H.
    Reykjavik, Iceland.
    Loftsson, Thorsteinn
    Reykjavik, Iceland.
    Stefansson, Einar
    Reykjavik, Iceland.
    Topical Dexamethasone gamma-Cyclodextrin Nanoparticle Eye Drops increase Visual Acuity and decrease Macular Thickness in Diabetic Macular Edema2015Ingår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, nr 7, artikel-id 2289Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Purpose: To test the efficacy and safety of topical 1.5% dexamethasone γ-cyclodextrin nanoparticle eye drops (dexNP) for diabetic macular edema (DME) and compare to posterior subtenon injection of triamcinolone acetonide.

    Methods: This was a prospective, randomized controlled trial with 22 eyes in 22 consecutive patients with DME, who were randomized to a) topical treatment with dexNP eye drops x3/day for one month, x2/day the next month and finally x1/day the third month or b) one posterior subtenon injection of 20mg triamcinolone acetonide.

    Results: The central macular thickness (CMT) decreased significantly with dexNP eye drops from 483±141mm to 384±142 mm at 4 weeks and 342±114 mm at 8 weeks. For triamcinolone, CMT decreased significantly at all time points. Visual acuity (logMAR) improved significantly with dexNP eye drops from 0.41±0.3 (mean±SD) to 0.32±0.25 and 0.30±0.26 at 4 and 8 weeks respectively. One third of the eye drop group improved more than 0.3 logMAR units. For triamcinolone, logMAR changed significantly from 0.42±0.28 at baseline to 0.32±0.29 at 4 weeks and 0.33±0.37 at 12 weeks. There was a modest increase in IOP at all time points with dexNP eye drops while no increase was seen with triamcinolone. Serum cortisol was affected by both treatments.

    Conclusions: Topical dexamethasone γ-cyclodextrin nanoparticle eye drops significantly improve visual acuity and decrease macular thickness in patients with DME. The effect is similar to that from subtenon triamcinolone as well as to reports on intravitreal steroid implants and triamcinolone intravitreal injections. A modest increase in IOP was seen with the nanoparticle eye drops but IOP normalized after discontinuation of treatment.

  • 30. Shulman, Shiri
    et al.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Stefánsson, Einar
    Loewenstein, Anat
    Rosenblatt, Amir
    Habot-Wilner, Zohar
    Topical dexamethasone-cyclodextrin nanoparticle eye drops for non-infectious Uveitic macular oedema and vitritis: a pilot study2015Ingår i: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 93, nr 5, s. 411-415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To evaluate the safety and efficacy of 1.5% dexamethasone nanoparticle (DexNP) drops in eyes with non-infectious uveitic macular oedema and vitritis. Methods: In a prospective pilot study, DexNP drops were administered four times a day for 4 weeks followed by drops tapering over a period of another 4 weeks. Follow-up time was 12 weeks. Results: Five eyes with macular oedema and three eyes with vitritis were included in the study. Best corrected visual acuity (BCVA) significantly improved from a median of 0.2 logMAR to a median of 0.15 logMAR at 4 weeks' time (p<0.05). Median BCVA was 0.175 logMAR and 0.2 logMAR, at week 8 and 12, respectively (p>0.05). Macular oedema significantly improved at all time-points as compared to baseline (p<0.05) and resolved in all eyes during follow-up. One eye had macular oedema relapse at week 12. Vitritis improved in all eyes and resolved completely in two eyes. One eye had intraocular pressure (IOP) elevation which was well controlled with topical antihypertensive treatment, and one eye had cataract progression. Conclusion: This short pilot study demonstrates favourable effect of 1.5% DexNP eye drops on eyes with non-infectious uveitic macular oedema and vitritis. Further comparative long-term studies are warranted to assess this effect.

1 - 30 av 30
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf