Amila Sampath Chandrasekera
Vision Care Optical Services PVT LTD, Sri Lanka
Title: Objective refraction measurement variations with off the axis retinoscopy
Biography
Biography: Amila Sampath Chandrasekera
Abstract
Aim: Objective of this study is to find the effect of off-the-visual axis retinoscopy on objective refractive measurement in routine clinical practice.
Material & Methods: Study was based on 450 subjects, with age range – 15-30 years; male were 225 and female were 225, and the study was conducted from 01.03.2015-25.4.2016; 150 myopes>(-3.00Ds/-1.00dc), 150 hyperopes > (+3.00Ds/-1.00dc), 150 emmetopes were selected for the study. Spherical refractive error +/- 3.00Ds and cylindrical error - 1.00Dc and the subjects with ocular pathology and strabismus are excluded. Retinoscopy was carried out in +/- 0.12 steps on visual axis (0 degrees) and at 50,100,150,200 off the visual axis. Targets were selected from snellen chart and presented isolated optotpes are of 6/60 letter size and the letters are attached to a mirrored wall at different eccentricities at a distance of 3 meters from the subject.
Results: Mean cylindrical error on off-the-visual-axis alignment was -0.32D,-0.40D,-0.51D,-0.72D at 50,100,150, 200 of eccentricity respectively which is statistically significant (p= 0.001).Group wise comparisons for mean cylindrical change in emmetropes and hyperopes statistically significant for different eccentricities from the visual axis with P value of 0.001, 0.003 & 0.367respectively. The mean spherical equivalent refractive error is -0.46,-0.55,-0.64,-0.56,-0.68 at 0, 5, 10, 15 and 20 degrees respectively and not statistical significant with p value of 0.98.
Conclusion: Off the axis refractions, even at small degrees of eccentricities resulted in significant errors in refractions.