PROSPECTIVE EVALUATION OF VISUAL ACUITY ASSESSMENT: A COMPARISON OF SNELLEN, FEINBLOOM, WITH ETDRS CHARTS ON LOW VISION PATIENT

ABSTRACT

The measurement of visual acuity is one of the most important and frequently administered tests in professional eye care. As such, it is important to use a method that is both accurate and repeatable. Commonly used tool for testing the visual acuities (VAs) of low vision subjects in both the clinical and research setting include Early Treatment Diabetic Retinopathy Study x (ETDRS) VA chart, Snellen’s chart and the Feinbloom’s chart. Hence, this study is aimed at evaluating charts used in the assessment of low vision patients. Patients were given the consent forms to fill and sign. Then a detailed case histories of the participants were taken. Followed by external examination with the penlight and internal examination with the ophthalmoscope. The visual acuities of the participants were then taken with the ETDRS chart (at both 4m and 2m), Snellen’s chart (6m and 3m) and Feinbloom’s chart (20 feet and 10 feet). Points within 95% limit Confidence intervals and none existence of proportional bias existed between ETDRS, Snellen’s and Feinbloom’s charts at distance of 4m, 6m and 20 feet respectively as shown by the Bland-Altman’s plots. While at distances of 2m, 3m and 10 feet there was proportional bias between the charts. The study comprised of 20 (50%) male and 14 (35%) female. Six (15%) of the participants did not specified their gender. The participants had a mean age of 28.68 ± 19.86 years (±SD) with an age range of 2 – 72 years (Table 1 and 2). The analysis of variance relationship between the ETDRS*Snellen’s chart and the ETDRS*Feinbloom’s charts revealed a non-statistically significant value. Albinism, 14 (35.90%) followed by optic atrophy, 5 (12.82% and end stage Glaucoma, 4 (10.26%) constituted major causes of low vision in the population.