Myopic glaucomatous eyes with or without optic disc shape alteration: a longitudinal study

AIMS: To compare the clinical courses of patients with myopic primary open angle glaucoma (POAG) with and without optic disc shape alterations. METHODS: In this longitudinal retrospective study, 146 eyes from 146 patients with myopic (axial length(AXL), >24 mm) POAG were classified according to optic disc shape alterations defined by optic disc tilt and/or rotation. Glaucomatous progression was determined by either serial optic disc/retinal nerve fibre layer photographs or visual field (VF) exams. Rate of progression was calculated from serial VF mean deviation (MD) and visual field index values. RESULTS: Mean age, AXL and follow-up duration were 50.1±12.7 years, 26.1±1.6 mm and 4.6±1.3 years, respectively. The progression rate was faster in eyes with a non-tilted optic disc than with a tilted optic disc (-0.30(95% CI; -0.42 to -0.16) vs 0.05(-0.07 to 0.17) dB/year, -0.85(-1.20 to -0.49) vs -0.35(-0.68 to -0.03) %/year, all p<0.05). Twenty eyes (21.3%) in the non-tilted group but only one eye (1.9%) in the tilted group showed VF progression in both superior and inferior hemifields. By logistic regression analysis, worse initial VF MD and less optic disc tilt were significantly associated with both superior and inferior VF progression (OR=0.909 and 0.561 (for 0.1 tilt ratio); p=0.020 and 0.018, respectively). CONCLUSION: Significant differences in glaucomatous progression were found between eyes with and without optic disc shape alterations, particularly disc tilt. More localised and stable courses of glaucoma progression were observed in eyes with tilted optic discs.