Abstract
Purpose:
Cycloplegic open field (OF) and closed field (CF) autorefractors give similar results in refractive errors among normal subjects according to previous literature. But in accommodative anomalies as in Pseudomyopia/ Accommodative spasm, the reliability of these techniques has not been tested. Hence we aimed to assess the difference in cycloplegic refraction between standard retinoscopy, CF and OF autorefraction techniques in Pseudomyopia.
Methods:
This cross-sectional hospital based study wascarried between November 2011 and November 2012. Pseudomyopia has been defined as discrepancy of 0.50D or more myopic in subjective acceptance compared to objective refraction along with a lead of accommodation in Dynamic retinoscopy by more than 0.50D. Subjects consented to undergo Cycloplegic refraction was prescribed with 1% Atropine eye drops twice a day for three consecutive days and the cycloplegic refraction values were documented on the fourth day using standard Retinoscopy, CF (Topcon RM -8900R) and OF (Grand Seiko WAM5500). The Spherical equivalent (SE) refractive error was considered the main outcome of the study.
Results:
Twenty eyes of ten pseudomyopic subjects were included. The mean (SD) age of the sample was 21 years (+ 6) with 7 females and 3 males. The mean (SD) SE using Retinoscopy was -3.21 D (2.50 D), using CF -4.13 D (2.83) and using OF was -3.39 D (2.67 D). The mean (SD) SE of subjective acceptance was -3.85 D (2.80). Paired t-test with adjusted p-value revealed significant difference between Retinoscopy and CF (Mean (SD) difference: 0.9 (0.7); CI (0.5 - 1.2); p <0.0001) and between OF and CF ((Mean (SD) difference: -0.74 (0.58); CI (-1 to -0.46); p <0.0001). Statistically insignificant difference was obtained between Retinoscopy and OF ((Mean (SD) difference: 0.18 (0.63) p = 0.21)
Conclusions:
Even under cycloplegia, closed field autorefraction over-estimates myopia significantly compared to standard retinoscopy and open field autorefraction techniques in Pseudomyopia. The clinician should consider this discrepancy in the management of Pseudomyopia.
Keywords: 605 myopia •
404 accommodation •
676 refraction