Comparisons of dynamic retinoscopy measurements with a print card, a video display terminal, and a PRIO System Tester as test targets.

Background: Dynamic retinoscopy is a common clinical test for assessment of visual function in patients with symptoms related to computer use. It has been suggested that performing dynamic retinoscopy with a fixation target resembling a computer screen may be valuable in the examination of computer users. However, such targets differ in luminance and other characteristics from the printed paper test cards typically used for dynamic retinoscopy.

Method: To address the effect of varying test targets on dynamic retinoscopy results, this study compared lag of accommodation results from dynamic retinoscopy with three different fixation targets: (a) a printed paper target, (b) a video display terminal, and (c) the PRIO vision testing device, which is designed to simulate a computer screen. MEM (monocular estimate method) dynamic retinoscopy was performed with the print target and with the PRIO device.

Results: The difference between results with the different test conditions were generally small, with a statistically significant 0.32 D lower lag found on MEM retinoscopy with the PRIO target IMEM-PRIO) than on MEM retinoscopy with a print target (MEM-PRINT). Mean lag measurements on MEM with a print target and on Nott retinoscopy with the video display terminal (NOTT-VDT) were only 0.04 D different. The 95% limits of agreement for the difference between MEM-PRINT and MEM-PRIO (+/- 0.6 D) was similar to the 95% limits of agreement for the interexaminer reliability of the two procedures (+/- 0.6 D for MEM-PRINT and +/- 0.7 D for MEM-PRIO).

Conclusion: There was a small but statistically significant difference in lag of accommodation measured with MEM dynamic retinoscopy on the PRIO testing device when compared to a print card.