Purpose:
To describe the study design and baseline factors of the Confocal Scanning Laser Ophthalmoscopy (HRT) ancillary study within the EGPS. This study was designed to examine the relationship between HRT optic disk topographic measurements and baseline demographic and ocular factors.
Methods:
Four-hundred eighty-nine eyes of 489 ocular hypertensive participants from 4 centers within the EGPS were investigated in this substudy. Each participant completed HRT imaging at least annually. Mean images for each image series were computed using software version 3.0. Contour line drawing and quality control was performed by two experienced glaucoma specialists at the HRT reading center Mainz, trained by the OHTS HRT reading Center. The association between the results of optic disk topography measurements and intraocular pressure (IOP), central corneal thickness (CCT), baseline photographic estimates vertical cup disk ratio, asymmetry between the two eyes in cup to disk ratio, and baseline visual field indices (pattern standard deviation, PSD) was assessed using regression analysis (univariate and multivariate).
Results:
489 eyes of 489 participants showed good quality images and could be included. Associations between optic disk topography measurements and vertical cup disk ratio were found for almost all stereometric optic disk parameter in both univariate and multivariate analysis. The strongest association was found between vertical cup disk measurements and disk, cup, and rim area, cup and rim volume, cup disk area ratio, linear cup disk area ratio, mean and maximum cup depth (all p < 0.0001). In multivariate analysis furthermore, significant associations were found between PSD, disk area, and HRT optic disk measurements (disk, cup, and rim area, cup and rim volume, cup disk area ratio, linear cup disk area ratio, and mean cup depth, p < 0.05)
Conclusions:
The EGPS is the first multicenter, placebo-controlled randomized clinical trial to use HRT for monitoring optic disk changes in participants with ocular hypertension. We found strong associations between vertical cup disk ratio estimates, disk area, PSD, and HRT stereometric parameters.
Keywords: clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • imaging/image analysis: clinical • optic disc