Comparison of Lea symbols and Snellen visual acuity charts in school aged children taking ETDRS as gold standard.

Abstract

OBJECTIVE: To compare results obtained by Lea symbols and Snellen visual acuity charts taking ETDRS as a gold standard.

PATIENTS AND METHODS: This study was conducted in the month of October and November 2015. It was an institution based study, conducted on 69 patients (including patient of age 5-10 years) visiting Orthoptic Clinic (Mayo Hospital Lahore). Each child had right eye and left eye visual acuity tested with Lea symbol chart, Snellen chart, and ETDRS chart. Visual acuity was scored as the smallest optotype size at which the child correctly identified 3 of a maximum of 5 optotypes.

RESULTS: Correlation between Lea symbols visual acuity and Snellen visual acuity was 0.68 (p < 0.001). Mean Lea symbols visual acuity was eight letters (0.16 logMAR) better than mean Snellen visual acuity (p < 0.001), and three letters (0.5 logMAR) better than the mean ETDRS visual acuity (p < 0.001). While ETDRS visual acuity was five letters (0.11 logMAR) better than mean Snellen visual acuity chart.

CONCLUSION: Visual acuity scores were significantly better on Lea symbols charts compared to Snellen charts, and ETDRS chart. The difference was great between ETDRS and Snellen charts, while the difference was small between ETDRS and Lea symbol.