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Purpose: To design, construct and validate a new Tamil logMAR visual acuity chart based on current recommendations., Methods: Ten Tamil letters of equal legibility were identified experimentally and were used in the chart. Two charts, one internally illuminated and one externally illuminated, were constructed for testing at 4 m distance. The repeatability of the two charts was tested. For validation, the two charts were compared with a standard English logMAR chart (ETDRS)., Results: When compared to the ETDRS chart, a difference of 0.06 +/- 0.07 and 0.07 +/- 0.07 logMAR was found for the internally and externally illuminated charts respectively. Limits of agreement between the internally illuminated Tamil logMAR chart and ETDRS chart were found to be (-0.08, 0.19), and (-0.07, 0.20) for the externally illuminated chart. The test - retest results showed a difference of 0.02 +/- 0.04 and 0.02 +/- 0.06 logMAR for the internally and externally illuminated charts respectively. Limits of agreement for repeated measurements for the internally illuminated Tamil logMAR chart were found to be (-0.06, 0.10), and (-0.10, 0.14) for the externally illuminated chart., Conclusions: The newly constructed Tamil logMAR charts have good repeatability. The difference in visual acuity scores between the newly constructed Tamil logMAR chart and the standard English logMAR chart was within acceptable limits. This new chart can be used for measuring visual acuity in the literate Tamil population.

Aim: The aim was to construct a visual acuity chart and find its effectiveness at screening visual acuity deficits. Materials and Methods: Two phases were involved in this study. Construction of the screener: Ten Sloan letters (C, D, H, K, N, O, R, S, V, and Z) were selected and the letters were constructed and reduced to 0.2 logMAR acuity size (6.92 mm) for viewing at 3 m. The screener contains three lines with seven letters in each. Few combinations of the seven letter sequences were chosen based on the row legibility scores. Three seven letter combinations close to the median of all combinations were selected, such that maximum difficulty score difference between the lines are <1%. Finding the effectiveness of the screener: 100 literate subjects with unaided visual acuity better than or equal to 6/60 were recruited for the study. Unaided visual acuity was tested using both the newly constructed Pocket Vision Screener and a logMAR visual acuity chart and the time taken to measure the visual acuity using both the charts was noted. Results: The mean age of the subjects was 43 ± 17 years. Subjects were classified as normal or deficient based on the logMAR visual acuity measurement. The screener was found to have 81% sensitivity, 94% specificity. The positive and negative predictive values were found to be 91% and 87%, respectively. A significant difference (P < 0.001) was found in the time taken to record visual acuity using both the charts. Conclusion: The Pocket Vision Screener can be used as a quick and accurate tool to screen subjects for visual acuity deficits, being highly sensitive, specific, and cost-effective. [ABSTRACT FROM AUTHOR]