title: Neurodegeneration in Type 2 Diabetes: Evidence From Spectral-Domain Optical Coherence Tomography.
abstract: OBJECTIVE
  The purpose of this study was to assess changes in the neural retina in eyes with different stages of diabetic retinopathy (DR) in comparison to age-matched healthy subjects.
  
  
  METHODS
  Retrospective analysis of spectral-domain optical coherence tomography (SD-OCT) scans of 76 naïve eyes of 62 subjects with diabetes was performed. Key exclusion criteria included presence of diabetic macular edema, any other retinal disease, history of any treatment for DR, or incorrect segmentation of the retinal layers on SD-OCT scans. Eyes from diabetic patients were divided into three groups, including no DR, nonproliferative DR (NPDR), and proliferative DR (PDR). A control group of 67 eyes of 66 age-matched healthy volunteers was included for comparison. Average, minimum, and sectoral thicknesses for the ganglion cell-inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL) were collected from both groups and compared using an ANOVA test.
  
  
  RESULTS
  Among the 76 included eyes, 43 had NPDR, 13 had PDR, and 20 had no signs of DR. Average and minimum GCIPL showed significant thinning in diabetic subjects compared with controls in all stages of DR (P < 0.05), especially involving the papillo-macula bundle. However, GCIPL thickness was similar between diabetic groups. There was no significant difference in average or sectoral RNFL thicknesses among groups; however, the minimum RNFL thickness was lower in diabetics compared with controls (P < 0.05). No relationship between GCIPL and RNFL thicknesses and duration of diabetes was present.
  
  
  CONCLUSIONS
  Early thinning on the inner retina happens in type 2 diabetes, even before visible vascular signs of DR. This supports the presence of a neurodegenerative process in eyes of patients with diabetes and warrants neuroprotective intervention to prevent chronic neurodegeneration. The SD-OCT may represent an indispensable tool for identifying early signs of neurodegeneration in diabetic patients.
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre LV Prasad Eye Institute, Hyderabad, India.
authors.forename: Jay
authors.initials: J
authors.lastname: Chhablani
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre LV Prasad Eye Institute, Hyderabad, India.
authors.forename: Apoorva
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre LV Prasad Eye Institute, Hyderabad, India.
authors.forename: Abhilash
authors.initials: A
authors.lastname: Goud
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre LV Prasad Eye Institute, Hyderabad, India.
authors.forename: Hari Kumar
authors.initials: HK
authors.lastname: Peguda
authors.affiliation: VST Glaucoma Center, LV Prasad Eye Institute, Banjara Hills, Hyderabad, India.
authors.forename: Harsha L
authors.initials: HL
authors.lastname: Rao
authors.affiliation: VST Glaucoma Center, LV Prasad Eye Institute, Banjara Hills, Hyderabad, India.
authors.forename: Viquar Unnisa
authors.initials: VU
authors.lastname: Begum
authors.affiliation: Genentech, Inc., South San Francisco, California, United States.
authors.forename: Giulio
authors.initials: G
authors.lastname: Barteselli
mesh_terms: D000328:Adult; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000175:diagnosis; D003930:Diabetic Retinopathy / Q000150:complications* / Q000175:diagnosis; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012160:Retina / Q000473:pathology*; D012162:Retinal Degeneration / Q000175:diagnosis* / Q000209:etiology; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods*; D014792:Visual Acuity