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Opposite clear corneal incision using different width keratomes for different types of astigmatism correction

Poster Details

First Author: P.Chiam UK

Co Author(s):    V. Ho              

Abstract Details


To improve the refractive outcome predictability of opposite clear corneal incision (OCCI) in cataract surgery using different width keratomes for against the rule astigmatism (ATRA) and with the rule astigmatism (WTRA).


Leighton Hospital, Crewe, UK Royal Liverpool University Hospital, Liverpool, UK


This is prospective study comprising of 54 eyes of 48 patients operated by a single surgeon (PJTC). Eyes with corneal pathology were excluded. All phacoemulsification was performed uneventfully. Patients underwent corneal keratometry with Zeiss IOLMaster 500 preoperatively. Eyes with keratometry of 1.5 to 2.5 D were included and divided into three groups of equal numbers (18 eyes). Group A had the steepest meridian at 90 ±25 degree (WTRA), whilst Group B and Group C at 180 ±25 degree (ATRA). The steepest corneal meridian was marked on the slit-lamp preoperatively. Eyes in Group A and Group B underwent OCCI at the steepest meridian with a 3.2mm keratome, and Group C with 3.5mm keratome prior to IOL insertion. Corneal keratometry and refraction were performed 3 months postoperatively. The primary efficacy outcome was the percentage change in the pre- and postoperative corneal keratometry. The secondary outcome was the absolute angle of error.


The mean age was 73 ±9 years and not significantly different between the three groups (P = 0.77). No patients had postoperative complication. The mean preoperative keratometry in Group A was 1.97 ±0.31 D, Group B was 2.02 ±0.29 D and Group C 2.12 ±0.26 D (one-way ANOVA, P = 0.31). Postoperatively, the reduction in keratometry in Group A was 83 ±10% (1.62 ±0.21 D), Group B 58 ±17% (1.16 ±0.28 D) and Group C 83 ±11% (1.75 ±0.28 D) (one-way ANOVA, P < 0.001). Post hoc tests showed reduction in astigmatism in Group B is statistically significantly different from Group A (P < 0.001) and Group C (P < 0.001). There was no difference between Group A and Group C (P = 0.99). The pre- and postoperative absolute angle of error in Group A was 10.0 ±8.1 degree, Group B 9.5 ±8.9, and Group C 11.2 ±6.7 (P = 0.78).


OCCI performed using different width keratome for different type of astigmatism is a simple method to increase its refractive surgical effectiveness and predictability.

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