Analysis of refractive errors in the eyes of young Indians

Abstract

The refractive errors of normal, healthy eyes were measured using an indigenously developed Shack–Hartmann aberrometer. Measurement was made in both right and left eyes after dilation for a 6 mm pupil size. The power vector method was used to represent the sphero-cylindrical errors. Analysis was done for astigmatism with the rule, oblique astigmatism and defocus between the right and left eyes of the subjects, which showed a negative, positive and zero correlation respectively. No correlation could be detected for RMS values between right and left eyes, though Zernike between right and left showed bilateral symmetry in our subjects. It was found that with an increase of spherical aberration, defocus decreased slightly. The validity and repeatability of our Shack–Hartmann aberrometry in measuring the refractive error was analysed and repeatability coefficient calculated. Optimal correction for greater retinal image quality has been discussed and far-point vergence for detecting the point of maximum retinal image quality is suggested.