title: Retinal Nerve Fiber Layer Thickness in Early-Stage Diabetic Retinopathy With Vitamin D Deficiency.
abstract: OBJECTIVE
  To evaluate retinal nerve fiber layer (RNFL) thickness in early-stage diabetic retinopathy (DR) patients with and without vitamin D deficiency (VDD).
  
  
  METHODS
  This study compared 50 early-stage DR patients with VDD (group 1) and 50 early-stage DR patients without VDD (group 2). All patients were examined by the same ophthalmologist. Mean RNFL thickness was determined by optical coherence tomography (OCT) performed by the two independent ophthalmologists for all subjects. Vitamin D levels were measured by using a radioimmunoassay. Vitamin D deficiency was defined, in accordance with the general standards, as a 25-hydroxyvitamin D (25(OH)D) level lower than 20 ng/mL.
  
  
  RESULTS
  There were no significant differences between the groups in terms of age and sex distribution (P > 0.05). The mean serum 25(OH)D concentration of group 1 was significantly lower than that of group 2 (P < 0.001). The mean RNFL thickness of group 1 was significantly reduced compared to that of group 2 (P < 0.001). A significant relationship between the mean RNFL thickness and serum 25(OH)D concentrations was observed in group 1 (P < 0.001).
  
  
  CONCLUSIONS
  The results indicate that vitamin D functions as a neuroprotective component for optic nerves. Low serum 25(OH)D concentrations contribute to RNLF thinning in early-stage DR patients with VDD.
authors.affiliation: Erzurum University Faculty of Medicine Internal Medicine, Department of Endocrinology and Metabolism, Erzurum, Turkey.
authors.forename: Adem
authors.initials: A
authors.lastname: Gungor
authors.affiliation: Erzurum University Faculty of Medicine, Department of Ophthalmology, Erzurum, Turkey.
authors.forename: Orhan
authors.initials: O
authors.lastname: Ates
authors.affiliation: Erzurum University Faculty of Medicine Internal Medicine, Department of Endocrinology and Metabolism, Erzurum, Turkey.
authors.forename: Habib
authors.initials: H
authors.lastname: Bilen
authors.affiliation: Erzurum University Faculty of Medicine, Department of Ophthalmology, Erzurum, Turkey.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Kocer
mesh_terms: D003930:Diabetic Retinopathy / Q000097:blood / Q000150:complications / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000379:methods*; D014792:Visual Acuity; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000473:pathology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D