title: Increased serum level of homocysteine correlates with retinal nerve fiber layer thinning in diabetic retinopathy.
abstract: To study the correlation between serum levels of vitamin B12, folic acid, and homocysteine and the severity of diabetic retinopathy and the correlation with retinal nerve fiber layer (RNFL) thinning on spectral domain optical coherence tomography (SD-OCT).
  
  
  
  In a tertiary care center-based prospective cross-sectional study, 60 consecutive cases and 20 healthy controls in the age group of 40-65 years were included. The eyes of the cases were divided into three groups according to Early Treatment Diabetic Retinopathy Study (ETDRS) classification: diabetes mellitus without retinopathy (n = 20), non-proliferative diabetic retinopathy with macular edema (n = 20), and proliferative diabetic retinopathy with macular edema (n = 20). The serum levels of vitamin B12and folic acid were measured using a standard protocol. The serum homocysteine assay was performed using an enzyme-linked immunosorbent assay (ELISA) kit. Average RNFL thickness was measured using SD-OCT. Statistical analysis was used to assess the correlations between the study variables.
  
  
  
  Increased severity of diabetic retinopathy was found to correlate with an increase in the serum levels of homocysteine (F = 53.79; p<0.001). The mean serum levels of vitamin B12and folic acid were found to be within the normal reference range. A positive correlation was found between retinal nerve fiber layer thinning and serum levels of homocysteine (p<0.001).
  
  
  
  This study, for the first time, demonstrated a correlation between increased homocysteine with a decrease in RNFL thickness and increased severity of diabetic retinopathy.
authors.affiliation: Retina Service, Department of Ophthalmology, King George's Medical University, Lucknow, India.
authors.forename: Khushboo
authors.initials: K
authors.lastname: Srivastav
authors.affiliation: Retina Service, Department of Ophthalmology, King George's Medical University, Lucknow, India.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Saxena
authors.affiliation: Department of Biochemistry, King George's Medical University, Lucknow, India.
authors.forename: Abbas A
authors.initials: AA
authors.lastname: Mahdi
authors.affiliation: CSIR - Indian Institute of Toxicology and Research, Lucknow, India.
authors.forename: Rajendra K
authors.initials: RK
authors.lastname: Shukla
authors.affiliation: Department of Ophthalmology, Pallas Clinic, Aarau, Switzerland.
authors.forename: Carsten H
authors.initials: CH
authors.lastname: Meyer
authors.affiliation: Vitreoretinal and uveitis service, Department of Ophthalmology, Saint Louis University School of Medicine,St. Louis, MO.
authors.forename: Levent
authors.initials: L
authors.lastname: Akduman
authors.affiliation: CSIR - Indian Institute of Toxicology and Research, Lucknow, India.
authors.forename: Vinay K
authors.initials: VK
authors.lastname: Khanna
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000097:blood* / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12