Effect of myopia on the progression of normal tension glaucoma

PURPOSE: Identify risk factors of progression in treated normal-tension glaucoma (NTG) in highly myopic and non-highly myopic eyes. METHODS: This retrospective, observational case series study included 42 highly myopic glaucoma (HMG, <-6D) eyes and 39 non-highly myopic glaucoma (NHG,≧-6D) eyes. Glaucoma progression was determined by serial visual field data. Univariate and multivariate logistic regression method were used to detect associations between potential risk factors and glaucoma progression. RESULTS: Among 81 eyes from 81 normal-tension glaucoma patients (mean follow-up, 3.10 years), 20 of 42 eye (45.24%) in the HMG and 14 of 39 eyes (35.90%) in the NHG showed progression. The HMG group had larger optic disc tilt ratio (p = 0.007) and thinner inferior macular thickness (P = 0.03) than the NHG group. Changes in the linear regression values for MD for each group were as follows: -0.652 dB/year for the HMG and -0.717 dB/year for the NHG (P = 0.298). Basal pattern standard deviation (PSD) (OR: 1.55, p = 0.016) and post treatment IOP (OR = 1.54, p = 0.043) were risk factors for visual field progression in normal tension glaucoma patients. In subgroup analysis of HMG patients, PSD (OR: 2.77, p = 0.017) was a risk factor for visual field progression. CONCLUSION: Reduction IOP was postulated to be contributing in the prevention of visual field progression, especially in highly myopic NTG patients with large basal pattern standard deviation.