Correlation Between Contrast Variability and Refractive Error

Abstract

Background: Contrast sensitivity, is defined as the ability to detect the lowest lumination difference between an object and the background. It is one of the main requisites for good quality vision as the eye works by perceiving an object by comparing the difference between the target and the background contrast difference. Aims and Objectives: To assess patterns of contrast sensitivity functions in patients in different types of refractive errors using Pelli Robson chart and also to measure the severity of refractive error within each group and compared the contrast sensitivity function with severity in different types of refractive errors. Material and Method: This cross-sectional study was conducted on 500 patients (Age range from 10 to 80 years) who presented with chief complaint of refractive errors mainly myopia and hypermetropia. Patients who had previous history of ocular surgery and other ocular co- morbidity were excluded from study. Selected patients were enrolled for the study after taking a written informed consent. The patterns of contrast sensitivity function in different types of refractive errors were recorded on a prescribed proforma with respect to: Visual acuity, type of refractive error, severity of refractive error, duration of refractive error, age of the patient, fundus examination and Contrast sensitivity. Statistical analysis was undertaken with P<0.05 significant. Results: A mild decrease in contrast sensitivity was recorded in majority of patients i.e 250 patients (50%). Maximum decrease in contrast sensitivity was seen in 31-60 years age group. A statistically significant direct correlation (P<0.05) was observed between duration and variation in contrast sensitivity. Both the refractive error showed definite decrease in contrast sensitivity and compound astigmatism showed severe decrease in contrast sensitivity. Conclusion: Despite having BCVA of 6/6, patients showed reduced contrast sensitivity, even without any retinal pathology, making it an essential part of a routine ophthalmic examination.