Perimetric Progression in Glaucoma Patients : Are Myopic and Non-myopic Eyes Different?

Purpose:To assess the asymmetry of visual field (VF) progression in myopic and non-myopic patients with primary open-angle glaucoma (POAG). Methods:In a retrospective study one randomly selected eye of 38 non-myopic POAG patients and 38 POAG patients with myopic correction 6 D was included. Each participant had a follow-up of at least 5 VFs over 5 years. The two groups were matched for age, gender, baseline Humphrey Field Analyzer Mean Defect (MD) and intraocular pressure. Patients with unreliable VF, learning effect, other forms of glaucoma or other factors that could affect the MD other than glaucoma were excluded. Progression was defined as the MD slope at regression analysis for each VF series. For each group, the difference in the slopes was calculated and compared by means of regression analysis and t-test. Results:The mean follow-up was 72 months for the myopic group and 81 months for the non-myopic group. Change in MD value of myopic (mean refraction -10 \ub1 4 D) and non-myopic eyes (mean refraction -0.3 \ub1 2 D) was, respectively, -2.21 dB and -1.98 dB. MD slope of myopic and non-myopic eyes was, respectively, -0.37 dB and -0.29 dB per year. Although myopic POAG patients tended to have a higher progression (y = 0.30x -1.32; R\ub2 = 0.14), such a difference was not statistically significant (P = 0.73). The study was powered 80% to detect a 0.3 dB difference per year. Conclusions:We found that perimetric progression rate in myopic and non-myopic POAG patients was not significantly different over a 5 years period. However as myopes tended to show a trend towards a higher progression, other studies with larger sample size and longer follow-up are advisable