Axial Length, Corneal Curvature and Their Association With the Refractive Status of the Eye

Abstract

AIMTo establish a definite correlation between the axial length, radius of cornea curvature and the refractive status of the eye. METHODSAll cases of emmetropia, myopia, hypermetropia, astigmatism between 20-30 years attending the Outpatient Department of Ophthalmology were informed about the purpose for the tests and the following were done. Visual acuity without and with correction, Subjective refraction, Fundus evaluation, Intraocular pressure, Keratometry. Ultrasound biometry to assess anterior chamber depth, lens thickness, axial length and vitreous chamber depth in all subjects in both eyes. RESULTSCorrelation between SE (Spherical equivalent) and AL/CRC; AL (Axial length), and CRC (Corneal radius of curvature), the highest and lowest AL/CRC values were seen in eyes with high myopia and high hyperopia, respectively. Mean AL/CRC was 3.49 in eyes with myopia greater than -5.0D; this value decreased linearly and reached a minimum of 2.65 in cases with hyperopia more than 2.0D. Linear regression showed a shift of 11.46D in SE refractive error towards myopia with every 1 unit increase in AL/CRC (P<0.001). CONCLUSIONRefractive error cannot be determined by a single optical component. It is the result of a combined interactive effect. The ratio of axial length and corneal radius of curvature seem to be a very reliable index of estimating the kind of resultant refractive error one might have. Axial length is the most influential factor in determining refraction radius curvature.