OP-1 Analysis and reporting of surgically induced keratometric effect (SIKE)

*Correspondence, Fadi Alfaqawi: fadi.alfaqawi@nhs.net PURPOSE: To investigate the surgically induced keratometric effect (SIKE) associated with cataract surgery. METHODS: Consecutive patients undergoing cataract operation by four surgeons were prospectively included. Two surgeons made an incision at 110 with one side port at 50 (location 1). Two surgeons made a temporal incision at 200 and 20 for right eyes and left eyes respectively, with two side ports (location 2). Biometry was acquired preoperatively and at 6-weeks postoperatively using an IOL Master 500 (Carl Zeiss Meditec, Jena, Germany) on the operated and unoperated fellow eye. Keratometric change was analysed after being transformed into Long's formalism. Coupling was defined as a change between the mean pre to post K that was less than the change in the unoperated eye. RESULTS: Two hundred patients were included, (132 in location 1 and 68 in location 2). There were significant differences in pre- to postoperative keratometry: location 1: preoperative and postoperative mean K were 43.65 (95%CI:40.27 to 47.04), 43.64 (95%CI:40.20 to 47.09) respectively, mean absolute difference 0.19 (SD0.19;p<0.01), location 2: preoperative and postoperative mean K were 43.29 (95%CI:39.89 to 46.70), 43.21 (95%CI:39.91 to 46.51) respectively, mean absolute difference 0.21 (SD0.21;p<0.01). For location 1, the mean SIKE was -0.23 @ 111/+0.21 @ 21 (95%CI:-1.43@122/+0.04 @ 32 to +1.04 @ 135/+0.30 @ 45). For location 2, the mean SIKE was -0.29 @ 104/+0.13 @ 14 (95%CI:-1.75@122/-0.19 @ 32 to +0.30 @ 47/+1.32 @ 137). Keratometric changes were not coupled in 69/132 (52%) for location 1 and in 42/68 (62%) for location 2, no significant difference between the coupling rate of location 1 and location 2 (p=0.51). CONCLUSION: The SIKE is relatively predictable for incision location and was surgeon independent. Coupling occurs in less than 50% of cases with a change in the mean keratometry.