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Laser treatment in glaucoma: efficacy and safety
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.ORCID iD: 0000-0002-4102-2455
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Glaucoma is a progressive optic neuropathy and the major cause of irreversible blindness worldwide. Although the pathogenesis of glaucoma is not completely understood, the most important risk factor for development and progression of the disease is an elevated intraocular pressure (IOP). Current glaucoma treatment aims to reduce the IOP in the affected eye. This can be achieved by topical drops, laser therapy or surgery. Laser treatment is used at different stages of the glaucoma disease. Some types of laser procedures are used as first-line treatments or as complement to topical medications or surgery, while other types are used in advanced glaucoma as a last option when other therapies have failed. Although laser therapy has long been used to reduce the IOP in glaucoma, knowledge gaps remain. The aim of this thesis was to evaluate the efficacy and safety, in both a short- and long-term perspective, of two of the most frequently used laser procedures in glaucoma: laser trabeculoplasty (LTP) and transscleral cyclophotocoagulation (TCP).

In the first study, a retrospective analysis, the long-term efficacy and safety of TCP was evaluated in 300 eyes of 300 glaucoma patients in northern Sweden. We found an overall substantial IOP reduction of more than 10 mmHg that was maintained at least 2 years in various types of glaucoma. Following TCP, the patients could reduce their treatment with an average of one substance of topical glaucoma medication in the treated eye. No case of phthisis bulbi, the most feared complication of TCP, was reported. However, a general decline in visual acuity (VA) was noted during the two-year follow up period, and the cause of this finding was difficult to assess due to the retrospective nature of the study.

The short-term effect of TCP on IOP was further investigated in a prospective study of 58 eyes of 58 glaucoma patients. IOP was measured at baseline before TCP and at five additional time-points up to 24 hours after the treatment. The VA was measured before TCP and at the 24 h examination. The results showed a transient IOP spike with a peak at six hours after TCP in approximately 40% of the eyes. Spikes were more common in eyes with pseudoexfoliation glaucoma.

The last two studies of the thesis focused on the short- and long-term efficacy of LTP. One-hundred fifty-two eyes of 122 newly diagnosed glaucoma patients that had been randomized to the multi-treated arm in the Glaucoma Intensive Treatment Study (GITS) were included. All studied eyes were treated with three different IOP-lowering substances and after one week, LTP was performed. We demonstrated that there was an additional IOP-lowering effect of LTP but that this effect was strongly associated with the level of IOP before the laser, where a higher IOP pre-LTP yielded a greater IOP reduction. Eyes with pre-laser IOP ³15 mmHg showed a significant IOP reduction that was maintained during four years of follow-up. However, in eyes with pre-LTP IOP <15 mmHg, the effect of laser treatment was limited.

In summary, this thesis investigated the efficacy and safety of TCP both retrospectively in a longer perspective and prospectively during the first 24 hours after treatment. An overall high efficacy without serious complications was shown, but a possible decline in VA must be considered in the long run. Furthermore, the risk of IOP spikes after TCP implies that additional IOP-lowering treatment should be considered during the first 24 hours, especially in eyes with pseudoexfoliation glaucoma or severe glaucoma damage. Finally, LTP may provide a valuable long-lasting IOP-lowering effect despite medical multi-treatment in eyes with a pre-LTP IOP ³15 mmHg.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2023. , p. 60
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 2239
Keywords [en]
glaucoma, laser treatment, intraocular pressure, glaucoma treatment
Keywords [sv]
glaukom, laserbehandling, ögontryck, glaukombehandling
National Category
Ophthalmology
Research subject
ophthalmology; ophthalmology
Identifiers
URN: urn:nbn:se:umu:diva-206004ISBN: 978-91-8070-013-9 (electronic)ISBN: 978-91-8070-012-2 (print)OAI: oai:DiVA.org:umu-206004DiVA, id: diva2:1746064
Public defence
2023-04-21, Umeälven, Målpunkt ZA-21, Psykiatrihuset, NUS, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Funder
Umeå UniversityKronprinsessan Margaretas MinnesfondEye FoundationAvailable from: 2023-03-31 Created: 2023-03-27 Last updated: 2023-03-28Bibliographically approved
List of papers
1. Efficacy and safety of transscleral cyclophotocoagulation in Swedish glaucoma patients
Open this publication in new window or tab >>Efficacy and safety of transscleral cyclophotocoagulation in Swedish glaucoma patients
2019 (English)In: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 97, no 8, p. 764-770Article in journal (Refereed) Published
Abstract [en]

Purpose: To retrospectively evaluate the efficacy and safety of all transscleral cyclophotocoagulation (TCP) treatments performed during a 5-year period.

Methods: Medical records of all patients, who had undergone TCP treatment between 2010 and 2014 at Umea University Hospital, Sweden, were evaluated. Clinical data including intraocular pressure (IOP), visual acuity (VA), number of topical glaucoma medications, use of oral acetazolamide, retreatments and complications during a 2-year follow-up were registered. Global success was defined as IOP 6-18 mmHg with or without glaucoma medication. 

Results: Three hundred patients underwent TCP during the time period. Mean IOP at baseline was 29.3 11.0 (mean +/- standard deviation) mmHg (n = 297) with a mean reduction of 11.5 (+/- 12.0) mmHg at 1 year (n = 258; p < 0.001) and 12.6 (<plus/minus>12.0) mmHg at 2-year follow-up (n = 245; p < 0.001). Global success at 2 years was 64%, achieved by a mean of 1.2 treatments (n = 257). The number of topical glaucoma medications at baseline was 3.1 (<plus/minus>1.0; n = 296) and was reduced by 0.9 (+/- 1.0) medications at 2 years (n = 244; p < 0.001). Use of oral acetazolamide decreased from 30% (n = 90) at baseline to 5.3% (n = 13) at 2 years. In eyes with Snellen VA <greater than or equal to> 0.1, the mean VA at baseline was 0.55 (+/- 0.3) logarithm of the minimum angle of resolution (logMAR; n = 132) and 1.1 (+/- 0.9) logMAR (n = 76) at 2 years (p < 0.001). No cases of phthisis bulbi were found.

Conclusion: This study displays a substantial and long-term reduction of IOP following TCP with a decrease in topical and oral glaucoma medications. The treatment appears to be safe but the decrease in VA during follow-up is a concern that needs further evaluation.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
intraocular pressure, laser treatment, open-angle glaucoma, pseudoexfoliation glaucoma, transscleral cyclophotocoagulation
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-166383 (URN)10.1111/aos.14125 (DOI)000496591800005 ()31025793 (PubMedID)2-s2.0-85065020711 (Scopus ID)
Available from: 2019-12-18 Created: 2019-12-18 Last updated: 2024-01-15Bibliographically approved
2. Changes in intraocular pressure during the first 24 hours after transscleral cyclophotocoagulation
Open this publication in new window or tab >>Changes in intraocular pressure during the first 24 hours after transscleral cyclophotocoagulation
(English)Manuscript (preprint) (Other academic)
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-206003 (URN)
Available from: 2023-03-27 Created: 2023-03-27 Last updated: 2024-01-15
3. Laser trabeculoplasty in newly diagnosed multi-treated glaucoma patients
Open this publication in new window or tab >>Laser trabeculoplasty in newly diagnosed multi-treated glaucoma patients
Show others...
2021 (English)In: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 99, no 3, p. 269-274Article in journal (Refereed) Published
Abstract [en]

Purpose: To evaluate the intraocular pressure (IOP)‐lowering effect of laser trabeculoplasty (LTP) in eyes which IOP had been substantially reduced by intensive topical treatment for one week.

Methods: Patients with newly diagnosed open‐angle glaucoma were randomized to treatment with three IOP‐lowering substances. One week later, 360° argon or selective LTP was performed. IOP was measured before LTP and at one‐, three‐, six‐ and 12‐month post‐LTP. The patients were part of the Glaucoma Intensive Treatment Study (GITS).

Results: Mean IOP (± SD) in 152 eyes of 122 patients was 14.0 (± 3.5) mmHg just before LTP. For every mmHg higher IOP prior to LTP, the IOP was reduced by an additional 0.6 mmHg at 12 months. The IOP was significantly reduced at all follow‐up visits from −2.6 (± 3.1) mmHg at one month to −2.1 (± 3.8) mmHg at 12 months in eyes with pre‐LTP IOP ≥ 15 mmHg, while no significant IOP reduction was seen in eyes with pre‐LTP IOP < 15 mmHg. Older age, argon LTP and male sex were associated with larger IOP reduction after 12 months, whereas presence of exfoliation syndrome was associated with a smaller IOP reduction. No severe complications were reported.

Conclusion: Success of LTP was highly dependent on the IOP level prior to LTP treatment. A sustained significant IOP reduction was seen in eyes with pre‐LTP IOP ≥ 15 mmHg whereas no such effect was seen in eyes with pre‐LTP IOP < 15 mmHg. Thus, LTP can be considered in eyes with multi‐treatment when target pressure of < 15 mmHg is not achieved.

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
Keywords
intraocular pressure, lasertrabeculoplasty, multitherapy, open-angle glaucoma, pseudoexfoliation glaucoma, SLT
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-176865 (URN)10.1111/aos.14576 (DOI)000585957600001 ()33124189 (PubMedID)2-s2.0-85094186017 (Scopus ID)
Available from: 2020-11-19 Created: 2020-11-19 Last updated: 2023-03-27Bibliographically approved
4. Long-term follow-up of laser trabeculoplasty in multi-treated glaucoma patients
Open this publication in new window or tab >>Long-term follow-up of laser trabeculoplasty in multi-treated glaucoma patients
Show others...
2024 (English)In: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 102, no 2, p. 179-185Article in journal (Refereed) Published
Abstract [en]

Purpose: To evaluate the long-term effect of laser trabeculoplasty (LTP) in patients randomized to multi-treatment in the Glaucoma Intensive Treatment Study (GITS).

Methods: Patients with untreated newly diagnosed open-angle glaucoma were treated with three intraocular pressure (IOP)-lowering substances for 1 week and then 360 degrees argon or selective LTP was performed. IOP was measured just before LTP and repeatedly during the 60-month study period. Our previous report on 12 months follow-up data revealed no effect of LTP in eyes having an IOP <15 mmHg before the laser treatment.

Results: Before LTP, the mean IOP +/- standard deviation in all 152 study-eyes of 122 multi-treated patients was 14.0 +/- 3.5 mmHg. Three eyes of three deceased patients were lost to follow-up during the 60 months. After exclusion of eyes that received increased therapy during follow-up, the IOP was significantly reduced at all visits up to 48 months in eyes with pre-LTP IOP >= 15 mmHg; 2.6 +/- 3.1 mmHg at 1 month and 1.7 +/- 2.8 mmHg at 48 months, n = 56 and 48, respectively. No significant IOP reduction was seen in eyes with pre-LTP IOP <15 mmHg. Seven eyes, i.e., <13%, with pre-LTP IOP >= 15 mmHg at baseline had required increased IOP-lowering therapy at 48 months.

Conclusion: LTP performed in multi-treated patients may provide a useful IOP reduction that is maintained over several years. This was true on a group level when the initial IOP was >= 15 mmHg, but if the pre-laser IOP was lower than that, chances of LTP success were small.

Place, publisher, year, edition, pages
John Wiley & Sons, 2024
Keywords
ALT, intraocular pressure, laser trabeculoplasty, long-term follow-up, multi-therapy, open-angle glaucoma, pseudoexfoliation glaucoma, SLT
National Category
Clinical Medicine Ophthalmology
Identifiers
urn:nbn:se:umu:diva-206002 (URN)10.1111/aos.15718 (DOI)001001069900001 ()37278271 (PubMedID)2-s2.0-85161487517 (Scopus ID)
Funder
Kronprinsessan Margaretas MinnesfondUmeå UniversityLund UniversityEye FoundationKonung Gustaf V:s och Drottning Victorias FrimurarestiftelseThe Swedish Medical AssociationSwedish Society for Medical Research (SSMF)Västerbotten County Council
Note

Originally included in thesis in manuscript form.

Available from: 2023-03-27 Created: 2023-03-27 Last updated: 2024-05-06Bibliographically approved

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