title: Retinal thickness profile of individuals with diabetes.
abstract: OBJECTIVE
  To examine the retinal thickness profiles of individuals with and without diabetic retinopathy (DR).
  
  
  METHODS
  Full retinal thickness in the central zone, overall and hemisphere thicknesses of the parafovea and perifovea, ganglion cell complex (GCC) thickness and retinal nerve fibre layer (RNFL) thickness were assessed in 185 individuals using spectral domain optical coherence tomography (88 individuals with diabetes but no DR, 55 with DR, and 42 non-diabetic controls). The DR group comprised of 60% of participants with very mild non-proliferative diabetic retinopathy (NPDR) (representing microaneurysms only) and 40% with mild NPDR (hard exudates, cotton-wool spots, and/or mild retinal haemorrhages). Regression analysis was performed to determine the factors associated with retinal tissue thickness, taking into account, age, sex, presence of DR, duration of diabetes, HbA1c levels and type of diabetes.
  
  
  RESULTS
  The mean (S.D.) of the overall parafoveal thickness was 306 (16) in the DR group and 314 (14) in the control group (p = 0.02). The mean (S.D.) of the superior hemisphere parafoveal thickness was 309 (16) in the DR group and 318 (14) in the control group (p = 0.02). The mean (S.D.) of the inferior hemisphere parafoveal thickness was 303 (17) in the DR group and 311 (15) in the control group (p = 0.02). There were no significant differences in retinal thickness between groups in the central zone (p = 0.27) or perifovea (p > 0.41). Neither the overall nor the hemisphere RNFL (p > 0.75) and GCC thickness (p > 0.37) were significantly different between the groups. Regression analysis revealed that parafoveal thickness in diabetic individuals was reduced in association with presence of DR (B = -5.9 μm, p = 0.02) and with advancing age (B = -4.5 μm, p = 0.004, for every 10 year increase in age) when adjusted for sex, duration of diabetes, HbA1c levels and type of diabetes.
  
  
  CONCLUSIONS
  The inner macula is thinner in the presence of clinical signs of diabetic retinopathy and is compounded by advancing age. The influence of any macular oedema or that by cotton-wool spots could not be ruled out and may still confound these results.
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Australia.
authors.forename: Sangeetha
authors.initials: S
authors.lastname: Srinivasan
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Australia.
authors.forename: Nicola
authors.initials: N
authors.lastname: Pritchard
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Australia.
authors.forename: Geoff P
authors.initials: GP
authors.lastname: Sampson
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Australia.
authors.forename: Katie
authors.initials: K
authors.lastname: Edwards
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Australia.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Vagenas
authors.affiliation: Princess Alexandra Hospital, Woolloongabba, Australia.|School of Medicine, University of Queensland, Woolloongabba, Australia.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Russell
authors.affiliation: Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, Manchester, UK.|Weill Cornell Medical College in Qatar, Doha, Qatar.
authors.forename: Rayaz A
authors.initials: RA
authors.lastname: Malik
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Efron
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000473:pathology*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012160:Retina / Q000473:pathology*; D012165:Retinal Ganglion Cells; D012307:Risk Factors; D041623:Tomography, Optical Coherence
chemical_list: D006442:Glycated Hemoglobin
keywords: diabetes; diabetic retinopathy; ganglion cell complex; retinal nerve fibre layer; retinal thickness