Paired opposite clear corneal incision (OCCI) versus limbal relaxing incision (LRI) for moderate astigmatism correction during cataract surgery

Session Details

Session Title: IOL technology/New IOLs etc.

Session Date/Time: Saturday 13/09/2014 | 08:30-10:30

Paper Time: 10:08

Venue: Boulevard A

First Author: : P.Chiam UK

Co Author(s): :    V. Ho   V. Romano   S. Kaye        

Abstract Details

Purpose:

To compare the predictability of OCCI and LRI in correcting corneal astigmatism during cataract surgery.

Setting:

Royal Liverpool University Hospital, UK

Methods:

One eye from each patient with corneal astigmatism (based on IOLMaster) between 1.00D and 2.25D was included in this study. A single mark was made at the 6 o’clock position on slit-lamp preoperatively. The Mendez ring was used to mark the steepest meridian intraoperatively. The eyes were randomly assigned to have OCCI or LRI with the intention to eliminate corneal astigmatism. OCCI was performed using a 2.8mm keratome (extended up to 3.2mm for higher astigmatism) on the steepest meridian and another at the opposite end. The LRI was based on a nomogram for 600microm depth. An adjustable diamond blade was used to make the recommended relaxing incisions about 1mm inside the limbus. Postoperative biometry and refraction were performed 6-8 weeks later. The data was analysed using matrix transformation.

Results:

All patients had uncomplicated cataract operation. OCCI was performed in 15 and LRI in 14 eyes. The mean age in the OCCI group was 77±8 (standard deviation) and LRI 79±8 (unpaired t-test, p=0.46). The preoperative corneal keratometry magnitude in the OCCI group was 1.7±0.3D and LRI 1.8±0.3D (unpaired t-test, p=0.17). The postoperative magnitude were 0.5±0.2D and 0.7±0.3D respectively (p=0.04). A change in steepest meridian of more than 20 degree between pre- and post-procedure occurred in 3 eyes in the OCCI group and one in LRI group. Matrix transformation was used to analyse the change in astigmatism. The difference between postoperative refraction and intended refraction compared to zero was statistically insignificant for OCCI (p=0.98) and LRI (p=0.76). The mean postoperative manifest refraction on the spectacle plane for OCCI was -0.28 / 0.12 X 178, and LRI -0.06 / 0.24 X 144. The surgically induced astigmatism for OCCI was 1.31D (range 0.59-1.71) and LRI 1.27D (range 0.55-1.87). All patients had reduction in the magnitude of the corneal astigmatism. Two eyes in the OCCI and 6 in the LRI group had postoperative corneal astigmatism of more than 0.75D. Only one eye had more than 1D of corneal astigmatism (from LRI group).

Conclusions:

Both OCCI and LRI were effective in reducing moderate amount of astigmatism during cataract surgery. OCCI seemed to be more predictable in achieving this.

Financial Interest:

NONE