Ocular Biometrics: Study of Myopia, Using A - Scan and Keratometer

ABSTRACT

Introduction: Myopia is a form of refractive error whichis a leading cause of visual disability throughout the world.The purpose of this study was to determine the variations inocular biometric parameters in various degrees of myopia i.e.low myopia (<-3D), moderate myopia (-3D to -6D) and highmyopia (>-6D).Method and Materials 200 eyes of 100 myopia patientswere examined. Keratometer and A-scan was done to measurethe corneal curvature and other biometric parameters like axiallength, anterior chamber depth, lens thickness and vitreousdepth respectively. Comparison of ocular components withage, gender and family history was done. One way ANOVAwas done to compare biometric parameters with refractivestates.Results: In our study, axial length(AL) (P=0.001), axial lengthto corneal curvature ratio(ALCRC) (P=<0.001), anteriorchamber depth(ACD) (P=<0.001) and vitreous depth(VD)(P=<0.001) were statically significant as compared to cornealcurvature(CC) (P=0.56) and lens thickness (P=0.64) whichwere statically insignificant.Conclusion: ALCRC and AL had more effect on highmyopia group as compared to corneal curvature. ALCRCratio was a better index for categorizing the refractive statusof an individual as compared to axial length alone. This ratiocan be considered at a cutoff point to categorise myopia intodegenerative myopia.