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

Abstract

Purpose: To compare refractive values measured without cycloplegia, cycloplegia and 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 to 26 years (mean 22.3 ± 3.7 years). The refraction measurement was obtained with autorefractor 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 +2.00D 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 analyzed 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 subject 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 (less effectiveness of 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 than cycloplegia when open-field autorefraction is performed in young adults.