[Computer aided, examiner independent screening for inapparent eye misalignment among 590 infants and preschoolers--a...

The purpose of the study was to investigate the computer aided screening method using Purkinje image I and IV reflection patterns for the detection of inapparent eye misalignment and to compare this to an orthoptic examination.

590 subjects up to 72 months of age with inapparent eye misalignment were recruited from the orthoptic outpatient department and externally. The computer aided screening consisted of taking a series of still video pictures with Purkinje reflection patterns. These were evaluated in an examiner independent way to reach a recommendation whether the child needed an ophthalmological referral or not. As gold standard, an orthoptic examination was performed. For analysis, the data were split by age groups. The orthoptic results were tested for certainty and repeatability.

The computer aided examination had the highest sensitivity of 0.82 in the age group up to 2.5 years of age, and a specificity of 0.90. With an estimated prevalence for microtropia of 0.01, the extrapolated positive predictive value was 0.08, and the negative predictive value was 0.998. In the age group up to 2.5 years of age, the percentage of orthoptic examinations without clear result (neither non-referral, nor strabismic) was 22.4%, and 6.1% in the screening examination. Among the cases which were examined repeatedly, some were classified as "strabismic" in the beginning, and as "non-referral" in the end in the orthoptic examinations.

The examiner independent, computer aided screening method is a cost effective option for the screening for inapparent eye misalignment, especially in the age group up to 2.5 years of age. If an orthoptic examination was carried out for screening, one should expect a higher rate of false positives, which entails more costly ophthalmological checks. Future studies should assess the validity of the single ortoptic examination as the gold standard in this age group.