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Field trial of the Otago photoscreener
Objective:
To assess the effectiveness of the Otago photoscreener in detecting amblyogenic factors in the general population.
Design:
Prospective clinical trial.
Setting:
Suburban school district in Delta, BC.
Participants:
A total of 1245 kindergarten children.
Interventions:
Screening for visual defects was done with the Otago photoscreener (by a technician) and the regular manual method (by a health care aide). A standard ophthalmologic examination was performed by a pediatric ophthalmologist and an orthoptist in a random sample of 20% of all children with normal results of screening (n = 241) plus all those with abnormal results (n = 29).
Main Outcome Measures:
Sensitivity, specificity, positive predictive value, rates of false-negative and false-positive results.
Results:
The Otago screener had higher sensitivity than the manual technique (81% vs. 33%), especially for strabismus and cataracts. The specificity values of the two techniques were 98% and 97% respectively, and the positive predictive values were 77% and 54% respectively. The manual technique failed to identify 5.8% of children with visual defects, compared with 1.6% for the Otago screener.
Conclusions:
The Otago photoscreener is a superior instrument for identifying amblyogenic eye disease. However, given the relatively low yield, the value of any screening method should be assessed with regard to both costs and benefits.