Abstract
Purpose: :
The EyeMapper (EM) is a closed-view global aberrometer developed at the Brien Holden Vision Institute (Sydney, Australia), that performs fast (<0.5 s) refraction scans across 100° of the visual field. The purpose of this study was to compare measurements obtained with and without cycloplegia in order to assess whether measurements are influenced by its closed-view design.
Methods: :
Forty-three participants (25 females) with an age range of 19-65 years (mean 34 +/- 12 years) and a spherical equivalent refractive error between +1.50D and -4.00D were recruited for the study. Five independent measurements of peripheral refraction and higher-order aberrations were recorded across the horizontal visual field, on both eyes of each subject under two conditions, always in the same sequence: a) non-cycloplegic measurements with +1D fogging lens (NC) and b) cycloplegia (CY). The non-measured eye was occluded. Two drops of 1% Tropicamide in a 5 min interval facilitated the cycloplegic measurements; the participants were refracted 30 minutes after the installation of the last drop.
Results: :
Overall, the NC mean spherical equivalent measures were found to be significantly more myopic than their CY counterparts (p<0.05); approximately by a magnitude of 0.50D centrally, increasing to 1.00D towards the periphery. For the astigmatic component J45, there was no significant difference between CY and NC. However, for J180, small but statistically significant differences up to 0.45D were found for eccentricities greater than 30° in both nasal and temporal meridians. C(4,0) was found to be significantly less positive in magnitude for the NC than the CY condition; this held true across the horizontal visual field. The coma coefficients C(3,-1) and C(3,1), were not significantly different between the NY and CY conditions, for most eccentricities, which is partly explained by the large inter-subject variability.
Conclusions: :
In this study, the use of fogging lens during non-cycloplegic refraction did not provide complete relaxation of accommodation. This may have implications in vision studies involving younger populations where accommodation control can be crucial. Accommodation affects the peripheral refraction more than central refraction for both, M and J180.
Clinical Trial: :
ACTRN12611001103954, 954
Keywords: accommodation • refraction • perimetry