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Topographic Indications of Emerging Keratoconus in Teenage New Zealanders

Owens, Helen PhD*; Gamble, Greg D MSc; Bjornholdt, Melissa C BSc*; Boyce, Nicola K MA, BOptom*; Keung, Lynnell BOptom*

doi: 10.1097/ICO.0b013e31802f8d87
Clinical Science
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Purpose: To screen a population of teenagers for emerging topographic signs of keratoconus (KC), with particular reference to ethnicity.

Methods: Corneal topography, visual acuity, and an environmental risk factor analysis were included in a screening program designed to identify early indications of potential KC in teenagers. Two schools from central North Island, New Zealand, were invited to participate: one with predominantly Maori/Polynesian students and the other with students of mainly European descent.

Results: A total of 198 Maori/Polynesian, 16.8 ± 1.05 years of age, and 243 European students, 16.2 ± 1.3 years of age, participated in the study. Corneal topography suggestive strongly of KC was evident in 3 Maori/Polynesian [1.2%; 95% confidence interval (CI): 0.3-4.3] and no European students (0%; 95% CI, 0%-1.5%). Anomalous corneal topography reminiscent of emerging KC in at least 1 eye were found in 19% (95% CI, 15.6%-22.9%). A significant difference (P = 0.0014) in the percentage of suspected KC was found between European students (12.9%; 95% CI, 9.2%-17.9%) and Maori/Polynesian students (26.9%; 95% CI, 21.0%-33.7%). In multivariate analyses, the significant independent predictors of probable or suspected KC included being Maori/Polynesian [odds ratio (OR) = 2.1; 95% CI, 1.25-3.54; P = 0.0052], increasing age (OR = 1.4; 95% CI, 1.10-1.80; P = 0.0067), and a history of hayfever (OR = 2.0; 95% CI, 1.16-3.59; P = 0.013). Topographical indicators that were associated significantly with suspected KC included central keratometry (P < 0.0001), astigmatism (P = 0.014), and inferior-superior asymmetry (P < 0.0001).

Conclusions: Although only a longitudinal study will determine the proportion of true KC candidates, these data provide evidence of ethnicity-related differences in corneal topography in teenage New Zealanders.

From the *Department of Optometry and Vision Science and the †Department of Medicine, The University of Auckland, Auckland, New Zealand.

Received for publication March 30, 2006; revision received November 5, 2006; accepted November 18, 2006.

Supported in part by New Zealand Optometric Vision Research Foundation and University of Auckland Staff research fund.

Reprints: Helen Owens, Department of Optometry and Vision Science, University of Auckland, Private Bag 92019, Auckland, New Zealand (e-mail: h.owens@auckland.ac.nz).

© 2007 Lippincott Williams & Wilkins, Inc.