Evaluation of the auto-refraction function of the Nidek OPD-Scan III

BackgroundThe aim was to evaluate the validity and repeatability of the auto-refraction function of the Nidek OPD-Scan III (Nidek Technologies, Gamagori, Japan) compared with non-cycloplegic subjective refraction. The Nidek OPD-Scan III is a new aberrometer/corneal topographer workstation based on the skiascopy principle. It combines a wavefront aberrometer, topographer, autorefractor, auto keratometer and pupillometer/pupillographer. MethodsObjective refraction results obtained using the Nidek OPD-Scan III were compared with non-cycloplegic subjective refraction for 108 eyes of 54 participants (29 female) with a mean age of 23.79.5 years. Intra-session and inter-session variability were assessed on 14 subjects (28 eyes). ResultsThe Nidek OPD-Scan III gave slightly more negative readings than results obtained by subjective refraction (Nidek mean difference -0.19 +/- 0.36 DS, p<0.01 for sphere; -0.19 +/- 0.35 DS, p<0.01 for mean spherical equivalent; -0.002 +/- 0.23 DC, p=0.91 for cylinder; -0.06 +/- 0.38 DC, p=0.30 for J(0) and -0.36 +/- 0.31 DC for J(45), p=0.29). Auto-refractor results for 74 per cent of spherical readings and 60 per cent of cylindrical powers were within +/- 0.25 of subjective refraction. There was high intra-session and inter-session repeatability for all parameters; 90 per cent of inter-session repeatability results were within 0.25 D. ConclusionThe Nidek OPD-Scan III gives valid and repeatable measures of objective refraction when compared with non-cycloplegic subjective refraction.