ABSTRACT
Purpose:
To compare the accuracy of best-corrected visual acuity in patients with diabetic retinopathy to corrected visual acuity ≤ 20/200 in both eyes, measured by Snellen and ETDRS charts, in addition to evaluation of reading time by Jaeger chart.
Methods:
An observational and cross-sectional study. Study Groups: Group I, patients with visual acuity 20/200, and Group II, patients with visual acuity >20/200. Patients were subdivided into those with non-proliferative diabetic retinopathy and with proliferative diabetic retinopathy. The study variables were sex, age, ETDRS chart in the subgroups (equal to 20/200; equal to 20/400 and greater than 20/200 and 20/400), and reading time by Jaeger chart on the near vision. The statistical significance was set at 5%.
Results:
A total of 62 diabetic patients participated in the study; in that, 33 with non-proliferative diabetic retinopathy and 29 with proliferative diabetic retinopathy. Among patients with non-proliferative diabetic retinopathy, 19 had best-corrected visual acuity 20/200 (30.6% of sample), and 13 patients had proliferative diabetic retinopathy with best-corrected visual acuity 20/200 (20.9% of sample). The correlation between the Snellen and ETDRS charts revealed 16 patients (25.8% of sample) with legal blindness presented visual acuity between 20/180 and 20/120, as per the ETDRS chart. For patients with non-proliferative diabetic retinopathy with visual acuity 20/200 measured by the ETDRS chart, the mean reading time to near vision was 23.6±1.4 seconds, as measured by Jaeger chart. In the statistical analysis, the comparison of visual acuity measured by Snellen chart, with the reading chart to near vision (Jaeger) measuring reading time, was statistically significant (p=0.04).
Conclusion:
Diabetic patients with legal blindness as per Snellen chart showed their real underestimated residual visual capacity. It is important to consider reading time and use of the ETDRS chart for better accuracy.
Keywords:
Visual acuity; Legal blindness; Reading; Ophthalmological diagnostic techniques