Abstract
Abstract: :
Purpose: To determine if central corneal thickness (CCT) predicts glaucoma severity upon patient presentation to a glaucoma specialist. Methods: Institutional review board approval was obtained. We retrospectively reviewed the initial visit of each consecutive new primary open angle or normal tension glaucoma patient who presented to one glaucoma specialist (LWH) from 1997 to 2002. Inclusion criteria were: pachymetry, reliable visual field tests, and optic disc stereo photographs or chart drawings. Exclusion criteria were: corneal or retinal pathology or secondary cause of glaucoma. We recorded per patient: age, sex, race, family history of glaucoma, and presence of diabetes mellitus or systemic hypertension. We recorded per eye: visual acuity, number of glaucoma medications, spherical equivalent, intraocular pressure, average CCT, visual field data, and vertical and horizontal cup-to-disc ratios. Humphrey visual fields were scored using modified Advanced Glaucoma Intervention Study (AGIS) criteria, and reliability parameters were recorded. One masked grader determined cup-to-disc ratios using photographs or drawings. Predictor variables were: age, sex, race, family history of glaucoma, spherical equivalent, intraocular pressure, and CCT. Outcome variables were: AGIS score, mean deviation of visual field, vertical and horizontal cup-to-disc ratios, and number of glaucoma medications. Each predictor variable was analyzed with each outcome variable. All predictor variables were then combined in a single regression model to assess their effects on the outcome variables. Right and left eyes were analyzed separately. Results: We reviewed the charts of 429 patients; 349 eyes of 196 patients met the inclusion and exclusion criteria. CCT was significantly lower in blacks (mean 540 microns) than in whites (mean 554 microns). Lower CCT was significantly predictive of higher AGIS score, more negative mean deviation of visual field, increased vertical and horizontal cup-to-disc ratios, and higher number of glaucoma medications. In multivariate analysis, CCT was the single determining predictor of AGIS score and of vertical and horizontal cup-to-disc ratios. CCT, age, and intraocular pressure were significantly predictive of mean deviation of visual field. Age, spherical equivalent, race, and family history of glaucoma were significantly predictive of number of glaucoma medications. Conclusions: CCT is the most powerful clinical predictor of glaucoma severity in our patients. Measuring CCT may aid the ophthalmologist to identify glaucoma patients at high risk of progression and to plan their therapy more aggressively.
Keywords: cornea: clinical science • visual fields • optic disc