A Study about the Accuracy of Automated Refraction

Kim, Yong Sik; An, Hyo Sook; Jin, Yong Han

Abstract

We analysed the differences between the values of noncycloplegicautomated refraction and manifest refraction by ophthalmologist 150 patients(274 eyes)were studied. We divided these patients into five groups according to the age; Group 1 included patients under 10 yea(n=50 eyes), Group 2 from 10 yrs to 19 yrs(n=74 eyes), Group 3 from 20 yrs to 39 yrs(n=66 eyes), Group 4 from 40 yrs to 49yrs(n=39 eyes), Group 5 over 50 yrs(n=46 eyes); We used Canon Auto Ref R-10 autorefractor and ophthalmologist's refractions were the results of both subjective refraction by retinoscope and objective refraction used by cross cylinder. Between the two examinations, the percentages of eyes of disagreement beyond +/-0.5D were 22%(group 1), 39.2%(group 2), 14.1%(group 3), 15.8%(group 4), 17.4%(group 5) in spherical power; 18%, 23%, 27.3%, 29%, 15.2% in cylindrical power respectively; 20%, 31.9%, 18.2%, 15.8%, 19.6% in spherical equivalent respectively and the percentages of eyes of disagreement beyond +/-10 degrees in cylindrical axis were 25%, 42.6%, 39.2%, 40%, 52.9% respectively. There was no statistic significance between the age groups when we compared the absolute differences of values between two examinations. Conclusively, this study revealed that there were large differences between the values of noncycloplegic automated refraction and manifest refraction by ophthalmologist in the large amout of patients and then our results indicated that automated refraction was dangerous to patient's eyes and subjective refinement was needed by ophthalmologist if patients wanted the spectacle or contact lens.