title: Retina and Choroid of Diabetic Patients Without Observed Retinal Vascular Changes: A Longitudinal Study.
abstract: OBJECTIVE
  To identify changes in choroidal thickness (CT) and all retinal layers of diabetic patients without diabetic retinopathy (DR) after 1 year of follow-up.
  
  
  METHODS
  Prospective observational cohort study.
  
  
  METHODS
  Overall, 125 diabetic patients without DR were included. Two visits were scheduled: the first visit (V1) and a second visit after 12 months (V2). At both visits, patients received a complete ophthalmologic evaluation that included OCT. Each retinal layer thickness was calculated for 9 ETDRS sectors, and CT was measured at 13 locations. Generalized linear mixed-effects models were used.
  
  
  RESULTS
  Of the 125 patients, 103 completed the study, and 9 of the 103 developed DR (8.7%). CT was significantly higher at V2 than at V1, with an average value of 10-17 μm at almost half the locations (500, 1000, and 1500 μm temporal; 500 and 1000 μm nasal; and 1000 μm superior to the fovea) (P < .001-.003). The thicknesses of the ganglion cell layer (I3 and N6 sectors), inner plexiform layer (S6 and N6 sectors), inner nuclear layer (T6 and N6 sectors), and outer plexiform layer (S6 sector), as well as the overall retinal thickness (RT) (S3, N3, I3, S6, and T6 sectors), were decreased at V2 (P < .001). Visible retinopathy was negatively associated with overall RT (central, S3, T3, I3, and N3 sectors, P = .004-.024) and the thickness of the ONL (T6 and I6 sectors, P = .007 and P = .009) and photoreceptor layer (N6 sector, P = .038). The presence of DR decreased the overall RT by 13.04-16.63 μm.
  
  
  CONCLUSIONS
  Diabetic patients without DR showed a thicker choroid and a thinner retina, particularly in inner layers, after 1 year of follow-up. These structural changes may correspond to the early neurodegenerative phase of DR.
authors.affiliation: Department of Ophthalmology, Central Lisbon Hospital Center, Lisbon, Portugal; NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal. Electronic address: joanaptf@gmail.com.
authors.forename: Joana
authors.initials: J
authors.lastname: Tavares Ferreira
authors.affiliation: Department of Ophthalmology, Central Lisbon Hospital Center, Lisbon, Portugal.
authors.forename: Rita
authors.initials: R
authors.lastname: Proença
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; NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal.
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Dias-Santos
authors.affiliation: Department of Ophthalmology, Associação Médica Olhar bem, Lisbon, Portugal; CEris-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; NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal.
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Cunha
authors.affiliation: Epidemiology and Statistics Unit, Research Centre, Central Lisbon Hospital Center, Lisbon, Portugal; NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal; CEAUL (Center of Statistics and Applications), Lisbon University, Lisbon, Portugal.
authors.forename: Ana Luísa
authors.initials: AL
authors.lastname: Papoila
authors.affiliation: Visual Sciences Study Center, Faculty of Medicine, Lisbon University, Lisbon, Portugal; Department of Ophthalmology, Northern Lisbon Hospital Center, Lisbon, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Abegão Pinto
mesh_terms: D000368:Aged; D002829:Choroid / Q000000981:diagnostic imaging*; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis*; D003930:Diabetic Retinopathy; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012160:Retina / Q000000981:diagnostic imaging*; D012720:Severity of Illness Index; D013997:Time Factors; D041623:Tomography, Optical Coherence / Q000379:methods*; D014792:Visual Acuity