Prediction of the Refractive Error Based on Snellen chart and OPD-scan III Visual Acuity

To predict the spherical refractive error and astigmatism based on Snellen chart and OPD-scan III visual acuity in visually normal individuals. This study was performed on seventy five participants with an age range of 18 to 35 years. Visual acuity and refractive errors were evaluated using both subjective Snellen chart and OPD-scan III devices. The Pearson correlation test was used to evaluate the correlation between visual acuity and refractive errors. Moreover, to predict refraction based on the visual acuity, linear regression was performed. The results of the Pearson correlation test showed a significant negative correlation between visual acuity and refractive error in the myopic group (p<0.0001, r=-0.859 for subjective visual acuity, r=-0.788 for objective visual acuity). In addition, there was a significant positive correlation in the hyperopic group (p<0.0001, r= 0.882 for objective visual acuity). However, there was no significant correlation between subjective visual acuity and spherical refractive errors. Also, no significant correlation was found between astigmatism and visual acuity of the eye (p>0.05). Considering the high correlation between visual acuity and spherical refractive errors in myopic groups, refraction may be estimated based on the visual acuity of the eye. While in hyperopic group, there is no possibility to predict the refraction based on subjective visual acuity. Considering the poor correlation between visual acuity and astigmatism, astigmatism cannot be estimated based on the visual acuity of the eye.