title: Analysis of retinal capillaries in patients with type 1 diabetes and nonproliferative diabetic retinopathy using adaptive optics imaging.
abstract: OBJECTIVE
  To illustrate a noninvasive method to analyze the retinal capillary lumen caliber in patients with Type 1 diabetes.
  
  
  METHODS
  Adaptive optics imaging of the retinal capillaries were acquired in two parafoveal regions of interest in eyes with nonproliferative diabetic retinopathy and unaffected controls. Measures of the retinal capillary lumen caliber were quantified using an algorithm written in Matlab by an independent observer in a masked manner. Comparison of the adaptive optics images with red-free and color wide fundus retinography images was also assessed.
  
  
  RESULTS
  Eight eyes with nonproliferative diabetic retinopathy (eight patients, study group), no macular edema, and preserved visual acuity and eight control eyes (eight healthy volunteers; control group) were analyzed. The repeatability of capillary lumen caliber measurements was 0.22 μm (3.5%) with the 95% confidence interval between 0.12 and 0.31 μm in the study group. It was 0.30 μm (4.1%) with the 95% confidence interval between 0.16 and 0.43 μm in the control group. The average capillary lumen caliber was significantly narrower in eyes with nonproliferative diabetic retinopathy (6.27 ± 1.63 μm) than in the control eyes (7.31 ± 1.59 μm, P = 0.002).
  
  
  CONCLUSIONS
  The authors demonstrated a noninvasive method to analyze, with micrometric scale of resolution, the lumen of retinal capillaries. The parafoveal capillaries were narrower in patients with Type 1 diabetes and nonproliferative diabetic retinopathy than in healthy subjects, showing the potential capability of adaptive optics imaging to detect pathologic variations of the retinal microvascular structures in vaso-occlusive diseases.
authors.affiliation: Fondazione G.B. Bietti IRCCS, Rome, Italy. mlombardo@visioeng.it
authors.forename: Marco
authors.initials: M
authors.lastname: Lombardo
authors.forename: Mariacristina
authors.initials: M
authors.lastname: Parravano
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Serrao
authors.forename: Pietro
authors.initials: P
authors.lastname: Ducoli
authors.forename: Mario
authors.initials: M
authors.lastname: Stirpe
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lombardo
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001813:Blood-Retinal Barrier; D002196:Capillaries / Q000473:pathology; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis*; D003930:Diabetic Retinopathy / Q000175:diagnosis*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D061848:Optical Imaging / Q000295:instrumentation*; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000473:pathology*; D014792:Visual Acuity / Q000502:physiology
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human