title: Longer axial length is protective of diabetic retinopathy and macular edema.
abstract: OBJECTIVE
  To assess the association of ocular biometric parameters and refractive error with diabetic retinopathy (DR) and diabetic macular edema (DME) in persons with diabetes.
  
  
  METHODS
  Cross-sectional, clinic-based study.
  
  
  METHODS
  Patients with diabetes aged 18 years or more from the Royal Victorian Eye and Ear Hospital, Victoria, Australia.
  
  
  METHODS
  Spherical equivalent (SE) refraction was assessed using objective autorefraction. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were measured using the IOLMaster (Carl Zeiss Meditech AG, Jena, Germany). Diabetic retinopathy was graded from 2-field retinal photographs using the modified Airlie House classification system. Diabetic macular edema was defined as absent or present from fundus photographs and confirmed by optical coherence tomography (Stratus, Carl Zeiss Meditech AG).
  
  
  METHODS
  Severity of DR was grouped as no DR, mild DR (Early Treatment of Diabetic Retinopathy Study [ETDRS] = 20), moderate DR (ETDRS = 31-43), and severe DR (ETDRS >43). Diabetic macular edema severity was classified as mild, moderate, or severe.
  
  
  RESULTS
  A total of 208 of 630 eyes (33.0%) had DR. In multivariate models, eyes with longer AL were less likely to have mild (odds ratio [OR], 0.58; 95% confidence interval [CI], 0.41-0.83; P = 0.006 per mm increase), moderate (OR, 0.73; 95% CI, 0.60-0.88; P = 0.002), and severe DR (OR, 0.67; 95% CI, 0.53-0.85; P=0.01), and had a lesser risk of mild (OR, 0.70; 95% CI, 0.56-0.86; P < 0.001) and moderate DME (OR, 0.72; 95% CI, 0.56-0.93; P=0.002) but not severe DME. No association was found for SE, ACD, and CC with DR.
  
  
  CONCLUSIONS
  In persons with diabetes, eyes with longer ALs are less likely to have DR and DME.
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia.
authors.forename: Ryan Eyn Kidd
authors.initials: RE
authors.lastname: Man
authors.forename: Muhammad Bayu
authors.initials: MB
authors.lastname: Sasongko
authors.forename: Sutharssna
authors.initials: S
authors.lastname: Sanmugasundram
authors.forename: Theona
authors.initials: T
authors.lastname: Nicolaou
authors.forename: Xie
authors.initials: X
authors.lastname: Jing
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.forename: Ecosse L
authors.initials: EL
authors.lastname: Lamoureux
mesh_terms: D000368:Aged; D058452:Axial Length, Eye / Q000473:pathology*; D001699:Biometry; D001786:Blood Glucose / Q000378:metabolism; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008055:Lipids / Q000097:blood; D008269:Macular Edema / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012030:Refractive Errors / Q000150:complications* / Q000175:diagnosis; D012307:Risk Factors; D041623:Tomography, Optical Coherence
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D008055:Lipids; C517652:hemoglobin A1c protein, human