A comparison of the Plusoptix S08 photorefractor to retinoscopy and cycloretinoscopy

BACKGROUND: The aim was to compare outcome measures of refractive error by the Plusoptix S08 photorefractor with measures obtained by retinoscopy and cycloretinoscopy in children. METHOD: The refractive error of the right eye of 144 non-strabismic children, aged 2.5 to 5.5 years, was determined by Plusoptix S08 photorefraction, retinoscopy and cycloretinoscopy. Agreement between outcome measures of refractive error (spherical error, cylindrical error and spherical equivalent) by the three techniques were tested by Bland-Altman limits of agreement. RESULTS: The mean difference for spherical equivalent results of photorefraction (P(se)) minus those of retinoscopy (R(se)) and photorefraction minus those of cycloretinoscopy (CR(se)) were +0.53 ± 0.62 D and -0.22 ± 0.75 D, respectively. The 95 per cent limits of agreement for spherical photorefraction with retinoscopy and cycloretinoscopy were ±1.22 D (range -0.69 to +1.75) and ±1.47 D (range -1.69 to +1.25), respectively. The mean difference for cylindrical results of photorefraction (P(c)) minus those of retinoscopy (R(c)) and Pc minus those of cycloretinoscopy (CR(c)) were +0.11 ± 0.39 D and +0.13 ± 0.44 D, respectively. The 95 per cent limits of agreement for P(c) with R(c) and CR(c) were ±0.76 D (range -0.65 to +0.87) and ±0.86 D (range -0.73 to +0.99), respectively. The mean and standard deviation of weighted axes difference, comparing Plusoptix S08 and retinoscopy was 0.25 ± 0.36 and comparing Plusoptix S08 and cycloretinoscopy was 0.29 ± 0.51. Eighty-two per cent of the spherical equivalent findings in photorefraction and cycloretinoscopy show a difference of within 1.00 D. Regarding cylindrical power, this percentage is 96.6 per cent. CONCLUSION: As the findings demonstrate a fairly good consistency between the results of the Plusoptix S08 Photorefractor without using cycloplegic agents and those of cycloretinoscopy, the Plusoptix S08 is a fairly accurate tool to estimate refractive errors of children in the limited working range of the instrument.