title: Axial length and proliferative diabetic retinopathy.
abstract: OBJECTIVE
  To determine the correlation between axial length and diabetic retinopathy (DR) in patients with diabetes mellitus for 10 years or more.
  
  
  METHODS
  This study was a prospective, observational, cross-sectional study. Patients with diabetes for 10 years or more were included. We excluded eyes with any other significant ocular disease or any prior intraocular surgery, except uncomplicated cataract surgery. Only one eye of each patient was included as the study eye. The severity of DR was graded as no DR, non-proliferative DR (NPDR), or proliferative DR (PDR). Axial length was measured by A-scan ultrasound (10 MHz Transducer, AL-2000 Biometer/Pachymeter; Tomey, Phoenix, AZ). Univariate logistic regression models were used to evaluate the relationship between the dependent variables (any DR, PDR) and all potential risk factors. Axial length and other factors with p value <0.1 were included in multivariate logistic regression models. Backward selection based on the likelihood ratio statistic was used to select the final models.
  
  
  RESULTS
  We included 166 eyes from 166 patients (93 female and 73 male; mean age, 68.8 years). The mean diabetes duration was 15.4 years. Fifty-four (32.5%) eyes had no DR, 72 (43.4%) eyes had NPDR, and 40 (24.1%) eyes had PDR. In univariate analysis, hypertension (p = 0.009), renal impairment (p = 0.079), and insulin use (p = 0.009) were associated with developing any DR. Hypertension (p = 0.042), renal impairment (p = 0.014), insulin use (p = 0.040), pseudophakia (p = 0.019), and axial length (p = 0.076) were associated with developing PDR. In multivariate analysis, hypertension (p = 0.005) and insulin use (p = 0.010) were associated with developing any DR. Hypertension (p = 0.020), renal impairment (p = 0.025), pseudophakia (p = 0.006), and axial length (p = 0.024) were associated with developing PDR.
  
  
  CONCLUSIONS
  This observational study suggests an inverse relationship between axial length and the development of PDR in patients with diabetes for 10 years or more. No relationship was found between axial length and the development of any DR.
authors.affiliation: Department of Ophthalmology, Chang Gung Memorial Hospital, Keelung, Taiwan.
authors.forename: Ko-Jen
authors.initials: KJ
authors.lastname: Yang
authors.forename: Chi-Chin
authors.initials: CC
authors.lastname: Sun
authors.forename: Wan-Chen
authors.initials: WC
authors.lastname: Ku
authors.forename: Lan-Hsin
authors.initials: LH
authors.lastname: Chuang
authors.forename: Soh Ching
authors.initials: SC
authors.lastname: Ng
authors.forename: Kuei-Mei
authors.initials: KM
authors.lastname: Chou
authors.forename: Sheng-Fong
authors.initials: SF
authors.lastname: Kuo
authors.forename: Ling
authors.initials: L
authors.lastname: Yeung
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D018450:Disease Progression; D005123:Eye / Q000000981:diagnostic imaging*; D005139:Eyeglasses / Q000592:standards*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D011305:Presbyopia / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D011446:Prospective Studies; D013624:Taiwan / Q000453:epidemiology; D014463:Ultrasonography; D018630:Vitreoretinopathy, Proliferative / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*