Comparative study of visual acuity measure up to the Bailey Lovie chart chart vs. chart of isolated letters in patients with refractive amblyopia between 5 and 12 years

Abstract

In amblyopia diagnostic there is important to choose the visual chart to measure the visual acuity: morfoscopic or angular since due to the crowding phenomenon it turns out logical that it is easily to discriminate isolated characters than linear characters. <em><strong>Objective:</strong></em> to determination if there are significant difference between the visual acuity results measured up to the Snellen chart , Bailey Lovie chart and chart of isolated letters in patients with refractive amblyopia between 5 and 12 years. Materials and <em><strong>Methods:</strong></em> there was realized a comparative study of the results of visual acuity, measured up to three charts in far vision in 20 patients (40 eyes) by confirmed diagnosis of refractive amblyopia between 5 and 12 years, at the Unit of Pediatric Optometry and visual Training of the Optometric Research Institute of LaSalle University in the period between February and April, 2007. <em><strong>Results:</strong></em> the Pearson’s coefficient of correlation shows a higher correlation between the visual acuity taked with isolated letter chart and Snellen chart (0,7200407) and the lowest correlation between the Snellen and Bailey Lovie’s charts (0,6425297). In the variance analysis, there were significative differences between the values of visual acuity of each chart (p < 0.05). Dunnet’s test (isolated letter chart as control) shows that there was statistically significative difference between the results of Bailey’s chart and isolated letter chart (p < 0.05). There were not statistical differences the value of acute visual with Snellen VS isolated letter chart. Conclusions: There is a high correlation and there isn´t significative difference between isolated letter and Snellen chart, probably due to the fact that both of them use the same letters, which can lead to a high rate of memorization. There exists significative difference and low degree of correlation between visual acuity with Bailey Lovie’s chart and isolated letter chart. The difference between the angular and morphoscopic visual acuity is determinant at the moment of taking the visual acuity in order to diagnose the crowding phenomenon in this patients.