Effect of myopia on the progression of primary open-angle glaucoma

Abstract

Purpose: To evaluate the effect of myopia on the progression of primary open-angle glaucoma.

Methods: In this retrospective cohort study, eyes were classified into nonmyopic (NMG, >0 diopters [D]), mild to moderate (MMG, 0 to -6 D), and highly myopic glaucoma (HMG, <-6 D) groups according to the level of spherical equivalent. Glaucoma progression was determined either by optic disc/retinal nerve fiber layer (RNFL) photographs or by serial visual field (VF) data. Cox's proportional hazard models were used to detect associations between potential risk factors and glaucoma progression.

Results: Among 369 eyes from 369 glaucoma patients (average follow-up, 4.4 years), 54 of 178 eyes (30.3%) in the NMG, 49 of 151 eyes (32.5%) in the MMG, and 8 of 40 eyes (20.0%) in the HMG showed progression. When VF was used as a progression criterion, thinner baseline RNFL (hazard ratio [HR]: 0.942, P < 0.001) was predictive of progression. When optic disc/RNFL photographs were used, worse baseline visual field mean deviation (VF MD) and thinner RNFL were associated. The HMG category was a preventive factor for optic disc/RNFL photographic progression (HR: 0.323, P = 0.031).

Conclusions: No levels of myopia were associated with glaucoma progression in our study. High myopia was a protective factor for optic disc/RNFL progression. These results may be interpreted as a lower progression detection rate because of the difficulty in detecting changes in the optic disc/RNFL in HMG, or as a consequence of some of highly myopic eyes that may not be true cases of glaucoma.

Keywords: glaucoma; myopia; progression.