Accuracy of the autorefractor PowerRefractor in clinical work - A comparative study

Background: The aim of this prospective study was to investigate accuracy and efficiency of the autorefractometer PowerRefractor compared to established autorefractometers and retinoscopy as standard method. Patients and Methods: 150 patients (300 eyes) were examined. Patients were initially (pupil not influenced) analyzed with the Power Refractor (PRneutral). After that a examination followed under standardized Cyclopentolat cycloplegia with the Power Refractor (PRcyclo), the hand-held Retinomax K-plus (Nikon), the table-top mounted RK-5 (Canon) and retinoscopy. Results: Deviation from retinoscopy (percentage of values with more than 1 dpt difference/maximal deviation): Sphere: PRneutral:66,3%/8,5 dpt; PRcyclo: 48%/5 dpt, RK-5: 26,7%/4,75 dpt; Retinomax K-plus: 6,7%/1,25 dpt; Cylinder: PRneutral: 12%/6,25 dpt; PRcyclo: 21%/4,75 dpt; RK-5: 1,3%/2,75 dpt; Retinomax K-plus: 2,3%/2,5 dpt; spherical equivalent: PRneutral: 44,7%/7,1 dpt; PRcyclo: 35,3%/5,4 dpt; RK-5: 9%/4,5 dpt; Retinomax K-plus: 1,3%/1,4 dpt; error of entire refraction: PRneutral: 62,7%/7,8 dpt; PRcyclo: 61,3%/7,3 dpt; RK-5: 24%/4,5 dpt; Retinomax K-plus: 14,7%/3,6 dpt Conclusions: The best accuracy compared to retinoscopy had Retinomax K-plus followed by RK-5. PowerRefractor had the biggest deviations of the tested devices. PowerRefractor may be a usefull device for screening small children and handicapped people because of the one meter observing distance. For a precise refraction especially in children a retinoscopy under cycloplegic conditions is still necessary.