Effectiveness of a pinhole method for visual acuity screening.

Visual acuity screening was performed in the home in an adult population, using a standardized, retroilluminated chart. A pinhole disk was utilized to retest those subjects who initially failed the screening. All subjects failing the screening with the pinholes, and an equal number of age-matched subjects passing the screening (controls), were asked to have a complete ophthalmologic examination, including a protocol refraction in an eye clinic (clinic examination). Without use of the pinhole disk, 14.4% of subjects failed to read a 20/40 line. Use of the pinholes reduced the failure rate to 6.9%. Fifty-seven percent of those failing and 55% of controls had the clinic examination. Determination of best-corrected visual acuity after protocol refraction in the clinic indicated that the false-positive rate (the percentage of subjects who failed the screening but had visual acuity of 20/40 or better on the clinic examination) for the screening was 26%, and the false-negative rate (the percentage of subjects who passed the screening but had visual acuity of worse than 20/40 on the clinic examination) was 1.5%. Use of a pinhole disk is highly effective for visual acuity screening, reducing the false-positive rate by more than half.