Background: Cataract constitutes one of the top three causes of blindness worldwide1 wherein the vision can be easily restored by a simple and effective surgery .Cataract surgery such as manual small incision cataract surgery has an effect on the corneal curvature. This gives an opportunity to correct pre–existing astigmatism.2 The current study is aimed to analyse the effect of side port incision and site of incision, superior or temporal, on SIA. Method: Descriptive, tertiary hospital based cross sectional study on 120 eyes with visually significant uncomplicated senile cataract; pre–existing WTR astigmatism operated by superior incision, with & without side port and pre–existing ATR operated by temporal incision, with & without side port. Result: Superior incision with side port: 90% ATR & 10% WTR shift with 27% resultant WTR & 73% ATR. Average SIA:1.34D. Temporal incision with side port:90% WTR shift &10% ATR shift with 57% resultant WTR & 43% ATR. Average SIA:0.74D. Superior incision without side port:90% ATR shift &10% WTR shift with 27% resultant WTR &73% ATR. Average SIA:1.41D. Temporal incision without side port:90% WTR shift &10% ATR shift with 53% resultant WTR & 47% ATR. Average SIA:0.79D. Conclusion: SIA induced by temporal incision is less than that by superior incision and there is no significant effect of side port incision on SIA. There is greater incidence of WTR shift after placing a temporal main incision.