The influence of test illuminance on visual acuity in patients with primary open-angle glaucoma and age-related macular degeneration

Abstract

PURPOSE. To study the influence of the illuminance level of test objects on the resolution of the visual analyzer in patients with primary open-angle glaucoma (POAG) and age-related macular degeneration (AMD), and assess the possibility of using the obtained results for early diagnosis of these eye diseases.METHODS. Visual acuity (VA) under controlled illumination conditions (from 50 to 400 lx) of test objects was assessed using the developed device in three groups: in 50 healthy subjects aged 37.08±10.19 years without ophthalmic pathology (group A), in 50 patients with early (Ia and IIa) stages of POAG aged 47.16±8.28 years (group B) and 50 patients aged 46.08±4.56 years (group C) with dry form of AMD (initial stage).RESULTS. With an increase in the illumination of test objects (IT) from 50 to 400 lx, the VA of healthy individuals significantly increases on average by δ=0.32 (from 1.0±0.22 to 1.32±0.24, p<0.01), while in POAG the increase in VA with an increase in IT is much less pronounced, averaging δ=0.12 (from 0.9±0.20 to 1.02±0.26, p<0.05). At the same time, starting from IT 150 lx and above, the differences between the values of VA in the control group and in the group of patients with POAG of the initial stages become significant (p<0.05). VA of patients with AMD with increasing IT practically does not change, remaining at a stable level: δ=0.04 (from 0.76±0.20 to 0.80±0.26, t=0.66, p>0.5). At the same time, the VA values in this group of patients for each illumination level are significantly lower (p<0.05) than the corresponding VA values in the control group (group A).CONCLUSION. The revealed regularities can be used for early diagnosis of the pathological process: an increase in VA at the maximum level of IT relative to the initial value by less than δ≤0.2 indicates pathology of the optic nerve (POAG), and the absence of significant changes in VA with an increase in IT (minimum values of δ) is characteristic of the pathological process in the macula (AMD).