title: Topographic indications of emerging keratoconus in teenage New Zealanders.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand. h.owens@auckland.ac.nz
authors.forename: Helen
authors.initials: H
authors.lastname: Owens
authors.forename: Greg D
authors.initials: GD
authors.lastname: Gamble
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Bjornholdt
authors.forename: Nicola K
authors.initials: NK
authors.lastname: Boyce
authors.forename: Lynnell
authors.initials: L
authors.lastname: Keung
mesh_terms: D000293:Adolescent; D044466:Asian People / Q000208:ethnology; D002648:Child; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis* / Q000208:ethnology; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D011114:Polynesia / Q000208:ethnology; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014792:Visual Acuity; D044465:White People / Q000208:ethnology