ABSTRACT
Purpose: On-axis retinoscopy is believed to be necessary for accurate determination of refractive error. The purpose of this study was to determine the effect of off-axis retinoscopy on objective refractive measurement. Methods: Eight volunteers underwent cycloplegic retinoscopy of their right eye on-axis, and at 5, 10, 15, and 20 degrees off-axis in adduction. A masked examiner performed all retinoscopy with randomization of the patient and axis refracted. Results: The average spherical retinoscopic value at 0, 5,10,15, and 20 degrees of off-axis alignment was -0.4, -0.9, -1, -1.38, and -1.8 diopters, respectively. The average sphero-equivalent retinoscopic value for each axis position was -0.02, -0.59, -0.45, -0.64, and -0.98 diopters, respectively. Cylinder power increased by an average of 3% for each degree of off-axis retinoscopy. Conclusion: Objective refractive measurement by retinoscopy is significantly altered by off-axis retinoscopy.
