Defining Glaucomatous Vision Loss in Large Datasets Based on the Temporal Relationship of Visual Field and Visual Acuity Loss

Abstract

Purpose : The mechanism of blindness among primary open-angle glaucoma (POAG) subjects is often non-glaucomatous comorbid disease. Determining the cause of blindness is important for understanding vision loss in POAG and developing treatment models. Chart review is effective for determining the mechanisms of blindness for small study cohorts; however, this approach is impractical for large datasets. Vision loss from glaucoma is characterized by loss of visual sensitivity in the central 24–30 degrees of the visual field (visual field damage) prior to loss of best corrected visual acuity (BCVA). The sensitivity and specificity of using visual field damage prior to loss of BCVA to define vision loss as glaucomatous was evaluated.

Methods : A retrospective chart review was conducted at the Department of Ophthalmology and Visual Science at UTHealth. Subjects ≥18 years old diagnosed with POAG between July 2011– September 2021, with irreversible decline in BCVA to ≤ 20/200 in at least 1 eye, were reviewed. Eyes with BCVA ≤20/200 at the initial visit were excluded. An eye was categorized as blind if BCVA ≤20/200 and/or visual field mean deviation (MD) was ≤ -22 dB. The most recent MD prior to the development of BCVA ≤20/200 was recorded and the cause of blindness at that timepoint was investigated.

Results : 165 eyes with BCVA of ≤20/200 were included. Mean age was 72 (±14) years. Based on chart review, POAG was the cause of blindness in 76 (46%) eyes and coexisting ocular diseases were the cause of blindness in 89 (54%) eyes.

Of 32 eyes with BCVA ≤20/200 due to POAG that underwent 24-2 Humphrey visual field stimulus III test, 30 (94%) had most recent prior MD ≤ -22 dB. Of 42 eyes BCVA ≤20/200 due to coexisting diseases, 9 (21%) had MD ≤ -22 dB. The causes of blindness among these eyes were retinal detachment (3), endophthalmitis (2), cerebral vascular accident (3), and pituitary tumor (1). The sensitivity of the visual field damage prior to loss of BCVA method was 94% and the specificity was 79%.

Conclusions : Among POAG eyes with BCVA ≤ 20/200, comorbid ocular conditions are the cause of the loss of visual acuity in 54% of eyes. The sensitivity of using visual field damage prior to loss of BCVA to define vision loss as glaucomatous was excellent; however, the specificity was fair. Additional criteria are required to increase specificity of this definition of blindness caused by POAG.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.