Prevalence and Spatial Concordance of Visual Field Deterioration in Fellow Eyes of Glaucoma Patients

Purpose: To examine the prevalence of visual field deterioration in contralateral eyes of patients with worsening open-angle glaucoma and to evaluate the spatial concordance of visual field deterioration between both eyes. Methods: One hundred sixteen open-angle glaucoma patients who underwent 8 or more visual field examinations over ≥6 years of follow-up were included. The rates of the fast and slow components of visual field decay for each of 52 visual field test locations were calculated with point-wise exponential regression analysis. The spatial concordance of visual field deterioration in contralateral eyes was evaluated with a concordance ratio (calculated as the number of overlapping locations divided by the total number of deteriorating locations) and by comparing the rate of decay in corresponding modified glaucoma hemifield test clusters. Results: The average visual field mean deviation (±standard deviation [SD]) was -8.5 (±6.4) dB and the mean (±SD) follow-up time was 9.0 (±1.6) years. Sixty-three patients had mild damage, 23 had moderate damage, and 30 had severe damage. The mean concordance ratio (±SD) was 0.46 (±0.32) for the mild group, 0.33(±0.27) for the moderate group, and 0.35 (±0.21) for the severe group. Thirty-one patients (27%) had deterioration in concordant locations (p < 0.05). Visual field deterioration was greater in the superior hemifield than the inferior hemifield (p < 0.05) when evaluated with both the concordance ratio and modified glaucoma hemifield test cluster analysis methods. Conclusions: There is only fair spatial concordance with regard to visual field deterioration between the both eyes of an individual. We conclude that testing algorithms taking advantage of inter-eye spatial concordance would not be particularly advantageous in the early detection of glaucomatous deterioration.