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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.

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.

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.

Purpose:  In recent years, Applanation Resonance Tonometry (ART) has been suggested for intraocular pressure (IOP) measurements. The manual version of ART (ART_manual) has been further developed, and to improve usability, an automatic servo-controlled prototype (ART_servo) has been proposed. The aim of this study was to assess the limits of agreement (LoA) of ART_manual and ART_servo 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 ART_manual was ±4.5 mmHg for both dynamic and static analyses. The 95% LoA of ART_servo 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 ART_manual fulfilled the ISO standard with both the dynamic and the static analysis techniques. ART_servo with static analysis was close to fulfilling the standard but failed to do so in the highest IOP range. ART_servo has the potential to greatly improve usability if further development is completed.