title: Abnormal retinal nerve fiber layer thickness and macula lutea in patients with mild cognitive impairment and Alzheimer's disease.
abstract: OBJECTIVE
  We investigated possible abnormalities in the retinal nerve fiber layer (RNFL) and macula lutea of patients diagnosed with Alzheimer's disease (AD) and mild cognitive impairment (MCI) and tested for any correlation with the severity of dementia.
  
  
  METHODS
  A total of 72 subjects, comprising 25 AD patients, 26 MCI patients and 21 healthy individuals (controls) were enrolled in this study. The thickness of the RNFL and volume of the macula lutea was determined using optical coherence tomography (OCT).
  
  
  RESULTS
  When compared with controls, we found statistically significant thinning of the RNFL in AD patients at all clock-hour positions except 12:00, and nasal quadrant, 2:00, 3:00 and 4:00. After adjusting several risk factors, the average thickness of the RNFL was reduced in MCI patients compared to AD patients, with specific reductions at inferior quadrant, 5:00 and 6:00. Compared to controls, MCI patients showed a significant decrease in RNFL thickness only in the temporal quadrant, 8:00, 9:00 and 10:00. We found significant reduction in the volume of the macula lutea both in AD and MCI patients. Finally, we could not establish any correlation between patient Mini-Mental State Examination (MMSE) scores (an estimation of the severity of cognitive impairment) and any OCT parameter.
  
  
  CONCLUSIONS
  Retinal degeneration in AD and MCI patients results in decreased thickness of the RNFL, and reduced macular volume in AD and MCI patients. However, there seems to be no correlation between these changes and the severity of dementia.
authors.affiliation: Department of Neurology, Beijing Tian Tan Hospital, Capital Medical University, People's Republic of China.
authors.forename: LiYan
authors.initials: L
authors.lastname: Gao
authors.affiliation: Department of Neurology, Dalian Municipal Friendship Hospital, Dalian, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Neurology, Dalian Municipal Friendship Hospital, Dalian, People's Republic of China.
authors.forename: XiaoHong
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Ophthalmology, Dalian Municipal Friendship Hospital, Dalian, People's Republic of China.
authors.forename: QuanHao
authors.initials: Q
authors.lastname: Bai
authors.affiliation: Department of Neurology, The Third People's Hospital of Dalian, Dalian, People's Republic of China. Electronic address: yyliuping@163.com.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology* / Q000523:psychology; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000473:pathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008266:Macula Lutea / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009483:Neuropsychological Tests; D012160:Retina / Q000473:pathology*; D012162:Retinal Degeneration / Q000503:physiopathology; D012307:Risk Factors; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: Alzheimer's disease; Mild cognitive impairment; Optical coherence tomography; Retinal nerve fiber layer