Assessment of clinical parameters by ethnicity in patients with keratoconus: a multi-country study.

Abstract

Purpose : A number of clinical parameters are useful for the diagnosis, monitoring of keratoconus (KC) progression and post-treatment follow-up. However, it is currently unclear whether the distribution of these parameters differ between ethnicities. We aimed to compare the distribution of these clinical parameters in KC patients in different ethnic groups.

Methods : KC patients were recruited from public and private ophthalmology clinics in Australia, Hong Kong and India. In this observational study, patients reported ethnicity based on familial origin. Ethnicity was categorized as European, Asian, Indian or Other. Subjects underwent routine clinical examination including refraction and corneal topography. The Wilcoxon rank-sum test was used to compare clinical parameters between ethnic groups.

Results : Data were available for 1,472 eyes from 736 KC patients. Of these, 408 (55%) were Europeans, 133 (18%) were Asian, 129 (18%) were Indian and 66 (9%) reported Other ethnicities. There were more males 453 (62%) than females in each ethnic group. The age of onset ranged from 12 to 78 years [Median 25 years, Interquartile range 19–34] and the median was in the third decade of life for each ethnicity. There was no statistical difference in age of onset between European patients compared to each of other ethnic groups (p>0.13), however, Indians tended to be older at onset compared to Asians (p=0.052) and those categorized as other ethnicities (p=0.035).Mean anterior corneal curvature was flatter among Europeans compared to each of the groups (p<0.035) and mean posterior corneal curvature was similar between ethnicities (p>0.116). Likewise, spherical equivalent was least severe among Europeans compared to other ethnicities (p<0.007). Mean corneal pachymetry was thinner among Indians than Europeans and Asians at the apex (p<0.001 for each) and at the thinnest location (p<0.037).

Conclusions : In general, KC patients with a European background presented with less severe indicators of disease compared to Indian and Asian patients. These findings have important clinical implications when interpreting studies from different regions and contribute to the understanding of risk factors and future management strategies of KC. Further investigation of KC presentation and progression patterns among various ethnic groups is warranted and could be achieved through the development of a global collaborative initiative.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.