title: Relationship of gender, body mass index, and axial length with central retinal thickness using optical coherence tomography.
abstract: BACKGROUND
  Optical coherence tomography (OCT) acquires cross-sectional retinal images with high resolution using low-coherence interferometry. Few studies have studied the effect of demographic data and ocular parameters that may affect central retinal thickness. In this study, these factors were used as parameters to analyse if any significant relationship exists with central retinal thickness.
  
  
  METHODS
  Volunteers with a best-corrected visual acuity of 6/12 or better and no evidence of ocular abnormalities or interventions were recruited from October 2001 to March 2003. Body mass index (BMI), autorefraction, and keratometry recordings were measured, followed by applanation tonometry and A-scan ultrasonography. The central retinal thickness of the right eye was analysed using a scan length of 3 cm. Another 25 eyes were selected for interobserver reproducibility.
  
  
  RESULTS
  In all, 117 normal subjects (60 male and 57 female subjects) were recruited. The mean thickness of the central retina with a diameter of 1 mm was 203+/-23 microm for male and 189+/-20 microm for female subjects. Age, intraocular pressure, and keratometric readings were not significantly correlated with central retinal thickness. Using multiple regression, gender, BMI, axial length, and signal-to-noise ratio (P<0.05) were significantly associated with the central retinal thickness. The intraclass correlation coefficient was 0.98 for interobserver reproducibility.
  
  
  CONCLUSIONS
  OCT has a high interobserver reproducibility. The male gender, larger BMI, and longer axial length are associated with a significantly thicker central retina and these parameters should be considered for assessing retinal thickening and baseline comparisons in future studies.
authors.affiliation: Lo Ka Chow Memorial Ophthalmic Centre, Tung Wah Eastern Hospital, Causeway Bay, Hong Kong. albertcmw@sinaman.com
authors.forename: A C M
authors.initials: AC
authors.lastname: Wong
authors.forename: C W N
authors.initials: CW
authors.lastname: Chan
authors.forename: S P
authors.initials: SP
authors.lastname: Hui
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001699:Biometry / Q000379:methods; D015992:Body Mass Index; D005123:Eye / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012160:Retina / Q000033:anatomy & histology*; D012727:Sex Characteristics; D041623:Tomography, Optical Coherence / Q000379:methods