Subjective and quantitative measurement of wavefront aberrations in nuclear cataracts - a retrospective case controlled study

Abstract

Purpose:To measure, quantify and compare Ocular Aberrations due to nuclear cataracts.Setting:Department of ophthalmology and school for ophthalmic technicians, college of medicine and health sciences, Sultan Qaboos University, Muscat, Oman.Design:Retrospective case controlled study.Methods:113 eyes of 77 patients with nuclear cataract (NC) were recruited from outpatient clinic of a major tertiary referral center for Ophthalmology. Patients having NC with no co-existing ocular pathologies were selected. All patients were subjected to wavefront aberrometry (make) using Hartmann-Shack (HS) aberrometer. Consents were taken from all patients. Higher order Aberrations (HOA) were calculated with Zernike polynomials up to the fourth order. For comparison 28 eyes of 15 subjects with no lenticular opacities (control group) were recruited and evaluated in an identical manner. No pupillary mydriasis was done in both groups.Results:Total aberrations were almost six times higher in NC group compared to control (normal) subjects. The HOA were 21 times higher in NC group, and coma was significantly higher in NC eyes compared to normal (control) group. The pupillary diameter was significantly larger in control group (5.48mm ± 1.0024, p<.001) compared to NC (3.05mm ± 1.9145) subjects (probably due to younger control age group). Amongst Zernike coefficients up to fourth order, two polynomials, defocus (Z20) and spherical aberration (Z42) were found to be significantly greater amongst NC group, compared to normal control group.Conclusion:Nuclear cataracts predominantly produce increased defocus and spherical aberrations. This could explain visual symptoms like image deterioration in spite of normal Visual acuity.