The impact of intraocular pressure fluctuations and other factors on conversion of ocular hypertension to primary open-angle glaucoma.

PURPOSE: To evaluate the role of intraocular pressure (IOP) fluctuations and other factors on conversion of ocular hypertension to open-angle glaucoma (OAG) within a retrospective, longitudinal cohort study. PATIENTS AND METHODS: The study population included patients with ocular hypertension defined by IOP > 21 mmHg with normal appearing optic discs and no visual field defect. IOP fluctuation, mean and maximum were examined in 61 eyes over a follow-up period of 36 months (standard deviation (SD) 24). All patients underwent at least two 48-h IOP profiles including night-time IOP measurements in the supine position, visual field examinations, Heidelberg retina tomograph analyses (HRT) and optic disc photographs. Regression analyses were performed to demonstrate the impact of IOP parameters, myopia, sex, cup/disc ratio and visual field results on conversion to glaucoma. RESULTS: While IOP fluctuation and mean did not impact conversion, myopia proved to be a risk factor (HR 14.4; 95% CI: [3.9-53.0]; p ≤ 0.001). Over an average of three years, 6/61 converted to OAG. The study yielded a mean long-term IOP over all available pressure profiles of 18.1 mmHg (SD 3.2) and an IOP fluctuation of 1.9 mmHg (SD 1.1) within a mostly treated cohort. Conversion-free five-year rate was 59.8%. CONCLUSIONS: The amount of fluctuation we measured in our study sample did not result in the development of glaucoma in treated ocular hypertension patients. Myopic subjects with ocular hypertension are at a higher risk for glaucoma conversion than non-myopic ocular hypertensive subjects are.

Value of disc topographic measurements for the discrimination of glaucoma suspects from early primary open angle glaucoma cases: A thin discriminative line.

PURPOSE: To determine the diagnostic value of optic nerve head (ONH) topographic parameters measured by swept-source optical coherence tomography (SS-OCT) in differentiating between early glaucoma cases, glaucoma suspects (GSs), and healthy eyes. METHODS: The files of GSs, those with an early primary open angle glaucoma (POAG) diagnosis, and healthy eyes were retrospectively screened. Demographic characteristics, retinal nerve fibre measurements, visual field examinations, and ONH topographic parameters, including rim area, disc area, vertical and horizontal cup-to-disc ratios (CDRs), and cup volume, were compared between the groups. A receiver operating characteristic (ROC) curve analysis was performed on the ONH parameters. RESULTS: A total of 170 eyes from 85 GSs, 114 eyes from 57 patients with a diagnosis of early POAG, and 70 healthy eyes from 48 subjects were included in the study. The median age was 52.1 ± 0.9 years for the POAG group, 60.2 ± 1.1 years for the GS group, and 60.5 ± 1.6 for the controls. In the comparison of the ONH parameters between the groups, only rim area statistically significantly differed between the POAG and GS groups. However, all ONH parameters statistically significantly differed between the GS and control groups (p< 0.05). The mean rim areas of the GS, POAG, and control groups were 1.278 ± 0.055 mm2, 1.073 ± 0.065 mm2, and 1.446 ± 0.055 mm2, respectively, being statistically significantly higher in the controls and lower in the POAG group (p < 0.001). The highest area under the curve (AUC) value belonged to vertical CDR for the discrimination of the eyes with POAG from healthy eyes [0.806 (0.728-0.869, p < 0.001] and rim area for the discrimination of POAG cases and GSs [0.728 (0.650-0.797, p < 0.001]. CONCLUSION: There are significant differences in all ONH parameters between the eyes of GSs and healthy eyes. For the discrimination of early POAG and GS cases, topographic disc parameters may have value. In this study, rim area significantly differed between the GS and POAG groups, and it had the highest AUC value amongst the evaluated ONH parameters in the discrimination of early POAG cases S GSs.

Validation of formula-predicted glaucomatous optic disc appearances: the Glaucoma Stereo Analysis Study.

AIMS: The Glaucoma Stereo Analysis Study (GSAS) is a multicentre collaborative study of the characteristics of glaucomatous optic disc morphology using a stereo fundus camera. Using the GSAS dataset, we previously established a formula for predicting different appearances of glaucomatous optic discs, although the formula lacked validation in an independent dataset. In this study, the formula was validated in another testing dataset. SUBJECTS AND METHODS: Testing dataset contained three-dimensionally analysed optic disc topographic parameters from 93 eyes with primary open-angle glaucoma; six topographic parameters (temporal and nasal rim-disc ratios, mean cup depth, height variation contour, disc tilt angle and rim decentring absolute value) were used for predicting different appearances of glaucomatous optic discs. The agreement between grader-classified optic disc types, that is, focal ischemic (FI), generalized enlargement, myopic glaucomatous (MY), and senile sclerotic (SS) and formula-predicted optic disc types, that is, pFI, pGE, pMY and pSS, were assessed. RESULTS: Based on this formula, the eyes were classified with pFI (21 eyes, 22.6%), pGE (27 eyes, 29.0%), pMY (26 eyes, 28.0%) and pSS (19 eyes, 20.4%) when the top predictive element based on the formula was considered as the optic disc appearance in each eye. The six topographic parameters used in the formula differed significantly among the four predicted optic disc types. Substantial agreement (κ = 0.7496) was seen for the top two predictive elements based on the formula that agreed with the graders' classification in 76 (81.7%) eyes. Among the four optic disc types, the levels of agreement were relatively lower in the SS type (κ = 0.3863-0.5729) compared with the other three optic disc types (κ = 0.7898-0.8956) even though the unclassifiable and mixed optic disc types were excluded from the testing dataset. CONCLUSION: The GSAS classification formula can predict and quantify each component of different optic disc appearances in each eye and provide a novel parameter to describe glaucomatous optic disc characteristics.

Optic disc topography in Malay patients with normal-tension glaucoma and primary open-angle glaucoma.

BACKGROUND: There are limited data concerning the optic disc topography in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG) patients living in Southeast Asian countries. This study aims to compare optic disc parameters in patients with NTG and POAG in Malaysia and to discuss the results in comparison with studies of NTG and POAG in other Asian countries. METHODS: This prospective cross-sectional study was performed in two hospitals with glaucoma service in Malaysia from 2010 to 2012. Seventy-seven patients of Malay ethnicity were enrolled in this study, including 32 NTG patients and 45 POAG patients. Using the Heidelberg Retinal Tomograph III, we measured optic disc area, cup area, rim area, cup volume, rim volume, cup-to-disc area ratio, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area. RESULTS: The eyes for NTG patients had significantly larger optic disc areas (2.65 [standard deviation, 0.41] vs 2.40 [standard deviation, 0.36] mm(2), respectively; P=0.006) and cup areas (1.54 [standard deviation, 0.43] vs 1.32 [standard deviation, 0.40] mm(2), respectively; P=0.027) compared with the eyes of POAG patients. Comparison of the other parameters between the two groups revealed no significant difference (P>0.050). The moderate and severe NTG patients showed significantly deeper cups and larger disc and cup areas when compared with the moderate and severe POAG patients (P<0.050). CONCLUSION: The NTG patients in this study have notably larger optic disc and cup areas than the POAG patients. Our observations are consistent with those reported in studies of NTG and POAG patients in Korea. The deeper cups and larger disc and cup areas may serve as indicators of severity when comparing NTG with POAG. However, these findings require verification with IOP and visual field results.

Relationships between central corneal thickness and optic disc topography in eyes with glaucoma, suspicion of glaucoma, or ocular hypertension.

PURPOSE: To identify relationships between central corneal thickness (CCT) and optic disc topography, as determined by scanning laser ophthalmoscopy (SLO), for patients seen in a specialist glaucoma service. METHODS: 272 eyes of 144 patients with primary open angle glaucoma (POAG; n = 71), normal tension glaucoma (NTG; n = 50), ocular hypertension (OH; n = 48) and those considered to be suspicious for glaucoma (GS; n = 103) underwent ultrasonic pachymetry and optic disc topography by SLO. Correlations between CCT and SLO parameter values were identified. A Bonferroni correction for multiple comparisons was performed and a p value of <0.0042 was considered significant. RESULTS: Mean CCT values were 533 mum (POAG), 530 mum (NTG), 550 mum (GS), and 565 mum (OH). As a group the GS and OH eyes had significantly thicker CCT values than eyes with POAG. In addition, the NTG eyes had significantly thinner CCT values than GS and OH eyes. Overall multiple SLO parameters correlated with CCT even after accounting for co-variance with age, refraction and inclusion of both eyes. Sub-group analysis indicated that 'optic disc rim area' positively correlated with CCT (r = 0.378) and 'cup to disc area ratio' negatively correlated with CCT (r = -0.370) in the POAG group. In the GS group the parameter 'area below reference' (a measure of cup volume) and 'mean cup depth' had negative correlations with CCT (r = -0.297 and -0.323) indicating that eyes with thinner than average corneal thickness measurements had larger and deeper cups. CONCLUSION: Thinner corneas appear to be associated with larger and deeper optic disc cups in the eyes of patients seen in a specialist glaucoma service.