An Objective Methodology to Assess Visual Acuity Using Visual Scanning Parameters

An objective methodology to assess visual acuity (VA) in infants was developed. The methodology is based on the analysis of visual scanning parameters when visual stimuli consisting of homogeneous targets and a target with gratings (TG) are presented. The percentage of time on the TG best predicted the ability of the subject to discriminate between the targets. Using this parameter, the likelihood ratio test was used to test the hypothesis that the TG was discriminated. VA is estimated as the highest spatial frequency for which the probability of false positive is lower than the probability of false negative for stimuli with lower spatial frequencies. VA estimates of 9 adults had an average error of 0.06 logMAR with a testing time of 3.5 minutes. These results suggest that if the attention of infants can be consistently maintained the new methodology will enable more accurate assessment of VA in infants.MAS