Influence of fogging lenses and cycloplegia on open-field automatic refraction.

PURPOSE To compare refractive values measured with and without cycloplegia, or with fogging lenses, using an open-field auto-refractor. METHODS One hundred and forty-two young adults were enrolled from a university population; 96 were female (67.6%) and 46 were male (32.4%), the age range was 18-26 years (mean 22.3 +/- 3.7 years). The refraction measurement was obtained for the right eye of each subject with the Grand Seiko Auto Ref/Keratometer WAM-5500 (GS) under three conditions, always in this sequence: (1) without cycloplegia (GS), (2) without cycloplegia but using a + 2.00 D fogging lens (GS_2D) and (3) with cycloplegia (GS_cycl). RESULTS When the average values of spherical equivalent were compared, both accommodation control strategies were almost equally successful: GS, M = -0.85 +/- 2.21 D; GC_2D, M = -0.53 +/- 2.10 D and GS_cycl, M = -0.57 +/- 2.24 D (Kruskal-Wallis test, p < 0.001). When the results were analysed separately for different refractive groups, emmetropes and hyperopes show statistically significant differences while myopes did not. When both accommodation strategies were compared there was a trend for more myopic subjects to display more negative values under cycloplegia, while low myopes, emmetropes and hyperopes tend to display more negative values with the +2.00 D fogging lenses, suggesting this was less effective for accommodation control. CONCLUSIONS Over-refraction through +2.00 D fogging lenses is useful to achieve additional relaxation of the accommodative response in a similar way to cycloplegia when open-field autorefraction is performed in young adults.