Analysis of the application of computerized optokinetic nystagmus analyzer in vision examination
TL;DR
The computerized OKN analyzer exhibits favorable reliability and practicability for VA testing in patients aged aged ≥ 6 years across different refractive errors, with accuracy that appears sufficient for screening and general clinical estimation of VA.
Abstract
To investigate the practicability, accuracy, and consistency of the computerized optokinetic nystagmus (OKN) analyzer for visual acuity (VA) measurement. Cross-sectional consistency evaluation study. A total of 219 subjects (13.48 ± 12.89 years, 115 males, 104 females) underwent bilateral VA testing using a computerized OKN analyzer and a traditional OKN drum. Additionally, 104 subjects (12.58 ± 12.05 years, 54 males, 50 females) were tested bilaterally with the computerized OKN analyzer and a standard logarithmic E chart (random order), including 80 myopic eyes (spherical equivalent [SE] ≤ -0.5 D) and 63 hyperopic eyes (SE ≥ + 0.5 D); VA was recorded in logMAR. Concordance rates between the OKN analyzer and OKN drum were calculated. Intraclass correlation coefficients (ICC) and Bland-Altman plots were used to assess the consistency between the OKN analyzer and a standard logarithmic E chart. Subjects completing the lightbox test were stratified by age (3–4 years, 5 years, 6 years, 7–18 years, 18–58 years), refractive error, and VA range to compare inter-method correlations. Compared with the OKN drum, the computerized OKN analyzer achieved a concordance rate of 74.00% (right eye) and 77.08% (left eye), indicating good agreement. For VA measurements, mean VA (logMAR) of the right eye was 0.24 ± 0.29 (OKN analyzer) vs. 0.24 ± 0.28 (lightbox); left eye was 0.25 ± 0.28 vs. 0.24 ± 0.29. ICC values were 0.92 (right eye) and 0.88 (left eye, both P < 0.001), confirming significant consistency. Bland-Altman analysis showed 95% limits of agreement of -0.228 to 0.233 (right eye) and − 0.266 to 0.293 (left eye). Inter-method consistency improved with age (highest in ≥ 18 years) and was stronger in myopic vs. hyperopic eyes. Notably, correlation weakened as VA improved, with the highest concordance in the 0.1–0.5 decimal VA. The computerized OKN analyzer exhibits favorable reliability and practicability for VA testing in patients aged ≥ 6 years across different refractive errors, with accuracy that appears sufficient for screening and general clinical estimation of VA. However, in very young children (3–4 years) and in eyes with normal VA, agreement with chart‑based VA is limited, and further validation is required.