Posters

Exploring inter-ocular asymmetry in corneal power from biometry measurements of a large cataract cohort

Poster Details

First Author: I. Sheriff UNITED KINGDOM

Co Author(s):    E. Yonova   O. Kailani   J. Thompson   C. Hammond   O. Mahroo        

Abstract Details

Purpose:

We have recently shown that right eyes are on average very slightly, but significantly, longer and more myopic than left eyes, possibly contributing to the small preponderance of retinal detachments in right eyes. Myopia is a function both of corneal power and axial length. If right eyes are more myopic, then they may be expected to have greater corneal power, unless the myopia is largely axial. We explored whether small right-left differences in corneal power might be discernible in a large cohort of cataract patients.

Setting:

Biometry measurements from consecutive cataract surgery patients at a single eye department in the United Kingdom.

Methods:

Biometry measurements from patients who had undergone operations over a 6.5 year period were reviewed, and average corneal power values were compared between the eyes for patients for whom measurements from both eyes were available (two-tailed paired t test). In the vast majority of cases, measurements had been made using the Zeiss IOLMaster (Carl Zeiss, Jena, Germany).

Results:

4,568 patients had both eyes operated on during the designated period, and so measurements for both eyes were available. Mean (SD) K values were 43.75 (1.54) dioptres and 43.81 (1.53) dioptres for right and left eyes respectively. The mean difference was 0.06 D, with left eyes having a significantly greater corneal power (p<0.0001). For axial lengths, mean (SD) values were 23.55 (1.40) and 23.50 (1.40) for right and left eyes respectively. Right eyes were on average significantly longer by 0.05 mm (p<0.0001).

Conclusions:

It would appear that on average right eyes are longer but have less corneal power than left eyes. The differences are small but highly statistically significant. This would be expected to lessen the inter-ocular difference in refractive error, and supports the notion of a coordinated scaling of the eye, such that elongation of the eye may be balanced by a reduction in corneal power.

Financial Disclosure:

NONE