Reading acuity and speed can be used as a measure of disease severity for patients with geographic atrophy, according to a study published in JAMA Ophthalmology. The research supports the use of reading performance as a functional outcome measure in interventional clinical trials. The researchers suggest that measures in clinical and low-vision care patients with atrophy should hone in on optimal vision.
The investigators included 150 eyes from 85 participants (mean age, 77.9 years; 60% women). They detected impaired reading performance with a median monocular reading acuity of 0.9 logarithm of the reading acuity determination (logRAD) and a reading speed of 52.8 words per minute.
On analysis, reading acuity was most associated with the best-corrected visual acuity (BCVA), the area of geographic atrophy in the central Early Treatment Diabetic Retinopathy Study (ETDRS) subfield, the classification of noncenter vs center-involving geographic atrophy, and the area of geographic atrophy in the inner-right ETDRS subfield. Reading speed was most associated with the BCVA and low-luminance visual acuity, as well as the area of geographic atrophy in the central ETDRS subfield, in the inner-right ETDRS subfield, and in the inner-upper ETDRS subfield.
The study demonstrates a stronger correlation between lesion-shape determinants and reading acuity. The longitudinal analysis bolstered these results, indicating that reading speed may outperform reading acuity with respect to the detection of change over time.
The cross-sectional analysis demonstrates a moderately closer relationship with structural measures such as the geographic atrophy association with structural measures at the level of the inner-right and inner-upper ETDRS subfields. Low-luminescence visual acuity was more relevant to reading speed than reading acuity. These findings indicate that reading acuity recapitulates best-corrected visual acuity at the preferred retinal loci, whereas reading speed informs retinal function in proximity to the preferred retinal loci.
In terms of clinical trials, the investigators suggest that reading speed seems to be more indicative of retinal function compared with BCVA, and could be better able to gauge less-correlated data than reading acuity. Another suggestion is that monocular testing should be separately determined in clinical trials, which usually entail treatment to the worse-seeing eye in light of safety.
Due to the high prediction accuracy for reading speed, “it could be considered to waive reading performance testing and use machine learning–based inferred reading speed as a surrogate outcome measure. Reading performance testing performed at baseline and the last visit of all participants, however, could help validate prediction accuracy,” investigators report.
Limitations of the current study include the limited sample size, which was underpowered in determining reading acuity and change over time. In terms of stability, the mean reading speed could have been more apt than the maximum reading speed, which was measured in the study.
Künzel, SH, Lindner, M, Sassen, J, et al. Association of reading performance in geographic atrophy secondary to age-related macular degeneration with visual function and structural biomarkers. JAMA Ophthalmol. Published online September 30, 2021. doi:10.1001/jamaophthalmol.2021.3826