A Longitudinal Study To Evaluate Effect Of Surgically Induced Astigmatism After Phacoemulsification Clear Corneal Incision Placed In The Steepest Meridian On Eyes With Pre Existing Astigmatism At Kles Hospital, Belagavi

Abstract

Background and objectives Of the total estimated 38 million blind people in the world, about 9 - 12 million are in India. 50-80 % of these people are blind due to cataract. The technique of ECCE became popular; but surgically induced astigmatism was very high due to sutures and longer incision length. Then came into picture manual SICS which proved better than ECCE but still there was little surgically induced astigmatism. After the introduction of phacoemulsification through small clear corneal incision induction of surgically induced astigmatism was very less. Thus, it has been proposed that by placing the incision on the steepest meridian by marking the magnitude of pre-existing astigmatism we can cause further reduction in surgically induced astigmatism. The purpose of the study is to see the beneficiary effect of an incision placed on the steepest meridian in controlling/ lowering the astigmatic outcome in eyes with pre-existing astigmatism and comparing effect of incisions at different sites. 1. To evaluate the effect of Surgically Induced Astigmatism (SIA) after phacoemulsification clear corneal incision in the steepest meridian on the magnitude of the Pre-existing astigmatism (PEA). 2. To map the magnitude of surgically induced astigmatism by incisions in positions Superior (S) and Temporal (T). Methodology The present one year longitudinal study was conducted in the Department of Ophthalmology, KLES Dr. Prabhakar Kore hospital and Medical Research Centre, Belagavi on patients undergoing cataract surgery during the period of 1st January 2014 – 31st December 2014. The study was approved by the Ethical and Research Committee of Jawaharlal Nehru Medical College, Belagavi. The patients undergoing phacoemulsification with pre-existing astigmatism ranging from 0.5 D – 1.5 D were selected for the study to evaluate surgically induced astigmatism after phacoemulsification clear corneal incision in the steepest meridian on the magnitude of the pre-existing astigmatism. Results In the present study the mean age was 60 years with majority of the patients in the range of 50-70 years. 56% patients were males and 44% patients were females. In the present study, 32% patients had 0.5 D of pre-existing astigmatism followed by 51% patients in the range of 0.5 – 1D and 17% patients had pre-existing astigmatism in the range of 1- 1.5 D. 93 % patients had post-operative astigmatism in the range of 0.0 - 0.5 D followed by 07 % patients in the range of 0.5 – 1D. 30% patients were reported to have no post-operative astigmatism. In the study, 54 % patients had SIA in the range of 0.0 - 0.50 D followed by 39% patients who had SIA in the range of 0.5 – 1 D and 05% in the range of 1 -1.5D. The result showed that the average SIA recorded was 0.54 D + 0.34 with p < 0.001 (Statistically significant). It was concluded using the paired‘t’ test. The SIA through the temporal incision was 0.70 D with standard deviation of 0.35. The SIA through the superior incision was 0.84 D with standard deviation of 0.49. But, this difference of SIA comparison between temporal and superior incision was not statistically significant (p = 0.145) In the temporal incision, pre-operatively 22 patients (54%) had pre-operative astigmatism in the range of 0.00 – 0.5 D whereas post-operatively 40 patients (98%) had post-operative astigmatism in the range of 0.00 – 0.5 D In the superior incision, pre-operatively 20 patients (49%) had pre-operative astigmatism in the range of 0.00 – 0.5 D, whereas post-operatively 36 patients (88%) had post-operative astigmatism in the range of 0.00 – 0.5 D. On taking temporal incision, the mean keratometric difference was 1.03 + 0.96 which was statistically significant (p<0.001). On taking superior incision, the mean keratometric difference was 0.92 + 0.95 which was statistically significant (p<0.001) The visual rehabilitation was good. 90% patients had UCVA in the range of 6/12 -6/6 and 95 % patients had BCVA in the range of 6/12 – 6/6. Conclusion and interpretation Choosing the clear corneal incision site based on the preoperative steepest meridian significantly decreased the keratometric astigmatism at the temporal and superior locations. As well as, temporal incision is evidently better than superior incision in minimizing surgically induced astigmatism.