title: Retinal Neurodegeneration in Diabetic Patients Without Diabetic Retinopathy.
abstract: To compare the thickness of all retinal layers between a nondiabetic group and diabetic patients without diabetic retinopathy (DR).
  
  
  
  Cross-sectional study, in which all subjects underwent an ophthalmic examination including optical coherence tomography. After automatic retinal segmentation, each retinal layer thickness (eight separate layers and overall thickness) was calculated in all nine Early Treatment Diabetic Retinopathy Study (ETDRS) areas. The choroidal thickness (CT) also was measured at five locations. Generalized additive regression models were used to analyze the data.
  
  
  
  A total of 175 patients were recruited, 50 nondiabetic subjects and 125 diabetic patients without DR, stratified into three groups according to diabetes duration: group I (<5 years, n = 55), group II (5-10 years, n = 39), and group III (>10 years, n = 31). Overall, groups I and III of diabetic patients had a decrease in the photoreceptor layer (PR) thickness, when compared with the nondiabetic subjects in six ETDRS areas (P < 0.0007). Patients with more recent diagnosis (group I) had thinner PR than those with moderate duration (group II). Interestingly, patients with longer known disease (group III) had the thinnest PR values. There were no overall differences in the remaining retinal parameters.
  
  
  
  Retinal thickness profile is not linear throughout disease duration. Even in the absence of funduscopic disease, PR layer in diabetic patients seems to differ from nondiabetic subjects, thus suggesting that some form of neurodegeneration may take place before clinical signs of vascular problems arise.
authors.affiliation: Department of Ophthalmology, Central Lisbon Hospital Center, Lisbon, Portugal 2NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Tavares Ferreira
authors.affiliation: Epidemiology and Statistics Unit, Research Centre, Central Lisbon Hospital Center, Lisbon, Portugal.
authors.forename: Marta
authors.initials: M
authors.lastname: Alves
authors.affiliation: Department of Ophthalmology, Central Lisbon Hospital Center, Lisbon, Portugal 2NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal.
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Dias-Santos
authors.affiliation: Department of Ophthalmology, Central Lisbon Hospital Center, Lisbon, Portugal.
authors.forename: Lívio
authors.initials: L
authors.lastname: Costa
authors.affiliation: Department of Ophthalmology, Associação Médica Olhar bem, Lisbon, Portugal 5CEris-ICIST, Instituto Superior Técnico, Lisbon University, Lisbon, Portugal.
authors.forename: Bruno Oliveira
authors.initials: BO
authors.lastname: Santos
authors.affiliation: Department of Ophthalmology, Central Lisbon Hospital Center, Lisbon, Portugal 2NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal.
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Cunha
authors.affiliation: NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal 3Epidemiology and Statistics Unit, Research Centre, Central Lisbon Hospital Center, Lisbon, Portugal 6CEAUL (Center of Statistics and Applications), Lisbon University, Lisbon, Portugal.
authors.forename: Ana Luísa
authors.initials: AL
authors.lastname: Papoila
authors.affiliation: Department of Ophthalmology, Northern Lisbon Hospital Center, Lisbon, Portugal 8Visual Sciences Study Center, Faculty of Medicine, Lisbon University, Lisbon, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Abegão Pinto
mesh_terms: D000368:Aged; D002829:Choroid / Q000473:pathology*; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000175:diagnosis; D003930:Diabetic Retinopathy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009887:Ophthalmoscopy; D012160:Retina / Q000473:pathology*; D012162:Retinal Degeneration / Q000175:diagnosis* / Q000209:etiology; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods*