Axial Length as a Risk Factor for Glaucomatous Progression

Abstract

Purpose: : To determine whether axial length (AXL) is a risk factor for glaucomatous development or progression in subjects with ocular hypertension (OHT), glaucomatous optic neuropathy (GON) or primary open angle glaucoma (POAG).

Methods: : This was an observational cohort study that enrolled 559 eyes of 376 subjects from two longitudinal studies (Diagnostic Innovations in Glaucoma Study - DIGS and African Descent and Evaluation Study - ADAGES), from which 166 eyes were diagnosed with OHT, 206 with GON, and 187 with POAG. Mean follow-up time was 4.8 ± 3.2 years. Diagnosis of POAG was based on repeatable abnormal visual fields (VF), regardless of optic nerve status, at the baseline, diagnosis of GON was based on masked assessment of optic disc stereophotographs and required normal visual fields, and diagnosis of OHT was based on intraocular pressures above 21mmHg with normal optic discs and normal VF. Progression was determined by Standard Automated Perimetry Guided Progression Analysis (GPA) for visual fields, and/or by masked assessment of serial optic disc stereophotographs performed by expert graders. Axial length measurements were acquired from all patients with the IOLMaster (Carl-Zeiss Meditec). The association between baseline AXL and glaucomatous progression was investigated by univariate and multivariate Cox proportional hazards regression models. Multivariate models were adjusted for age, intraocular pressure (IOP), central corneal thickness (CCT), cup-disc ratio, and pattern standard deviation (PSD).

Results: : During the follow-up period, 84 (14%) eyes showed progression by stereophotographs and/or GPA. Mean axial length was 23.9 mm (range 18.5 to 27.4). Axial length was not predictive of glaucomatous progression in any one of the three groups, both in univariate and multivariate analysis. Hazard ratios (95% CI) were 0.60 (0.33 - 1.10) for progression in the OHT group, 0.83 (0.62 - 1.12) in the GON group, and 1.12 (0.77 - 1.61) in the POAG group.

Conclusions: : We were not able to find an association between axial length and risk of glaucoma development or progression in patients suspected of having disease or with established glaucomatous damage.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment • optic disc • detection