Comparison of an Italian chart with an Iranian chart in visual acuity measurement

ABSTRACT

Taking visual acuity is an important part of an eye routine examination. This study was conducted to compare visual acuity measured using an Iranian digital tumbling E chart with visual acuity measured using an Italian digital tumbling E chart as a familiar foreign chart. This study was carried out on 200 participants [400 eyes; healthy n=40, glaucoma n=40, retinal disorders n=40, post lasik n=40, corneal n=40] with mean age 44.28 years. Visual acuity of both eyes in half of the subjects [n=100, n=20 from each group] was first measured using the Italian digital chart and then measured using Iranian digital chart. Visual acuity of the rest of subjects [n=100, n=200 from each group] was first measured using the Iranian digital chart and then measured using the Italian digital chart. Measured visual acuities were recorded in logMAR notation. Mean of the Iranian and Italian Tumbling E chart is 0.280 +/- 0.012 and 0.277 +/- 0.012, respectively. Paired t-test used to evaluate the mean difference between two groups [p=0.721] indicated that there was no statistically significant difference between means of the two tests. Spearman correlation coefficient for the results of both tests was 0.942 [p<0.001], which was statistically significant and could be categorized as a strong positive correlation. The two digital Tumbling E charts acted similarly at different levels of acuity in different disorders. However, the Iranian chart requires a more accurate design for optotypes of the lower acuity lines in order to obtain more accurate measurement of visual acuities in healthy subjects: