Efficacy of SRKT biometry formula

ABSTRACT

To evaluate the predictive accuracy of SRKT formula in biometry. Two hundred eyes which underwent cataract extraction by phacoemulsification and implantation of a posterior-chamber intraocular lens were included in the study. Depending upon the axial length the patients were divided in four groups. Group-l Axial length<22 mm, n=28 eyes [14%].Group-2 Axial Length 22.00-24.5 mm, n=136 [68%]. Group-3 Axial Length 24.6-26 mm, n=25 eyes [12.5%]. Group-4 Axial Length > 26 mm, n=11 eyes [5.5%]. In all patients SRKT formula was used to calculate the power of intraocular lens. Group-I The mean deviation in refraction was 0.42D with SRKT and 0.56D with RCOphth guidelines. Group-2 The mean deviation in refraction was 0.62D with SRKT and 0.59D with RCO guidelines. Group-3 The mean deviation in refraction was 0.43D with SRKT and 0.41D with RCOphth guidelines. Group-4 The mean deviation in refraction was 0.42D with SRKT [RCOphth recommends the same formula for this length of eye ball]. When the overall mean deviation [of all four groups] was calculated, it was 0.56D for SRKT [range 0 to 2.81D] and was 0.52 D if RCOphth guidelines had been followed. Postoperative BCVA of 6/12 or better was achieved in 197 eyes [98%]. SRKT formula performed credibly in average-length eyes as well as in the long eyes. For short eyes results would have been better if Hoffer Q formula had been used