title: Retinal ganglion cell analysis using high-definition optical coherence tomography in patients with mild cognitive impairment and Alzheimer's disease.
abstract: BACKGROUND
  Alzheimer's disease (AD) is a neurodegenerative disorder with emerging evidence that it is associated with retinal ganglion cell loss; however, few data exist to establish this association.
  
  
  OBJECTIVE
  To determine whether macular ganglion cell-inner plexiform layer (GC-IPL) and retinal nerve fiber layer (RNFL), as quantitatively measured by non-invasive in vivo spectral-domain optical coherence tomography (SD-OCT), are altered in patients with AD and mild cognitive impairment (MCI).
  
  
  METHODS
  Patients with AD and MCI were recruited from dementia/memory clinics, and cognitively normal controls were selected from the Singapore Epidemiology of Eye Disease program. SD-OCT (Cirrus HD-OCT, software version 6.0.2, Carl Zeiss Meditec Inc, Dublin, CA) was used to measure the GC-IPL and RNFL thicknesses.
  
  
  RESULTS
  Compared with cognitively normal controls (n = 123), patients with AD (n = 100) had significantly reduced GC-IPL thicknesses in all six (superior, superonasal, inferonasal, inferior, inferotemporal, and superotemporal) sectors (mean differences from -3.42 to -4.99 μm, all p < 0.05) and reduced RNFL thickness in superior quadrant (-6.04 μm, p = 0.039). Patients with MCI (n = 41) also had significantly reduced GC-IPL thicknesses compared with controls (mean differences from -3.62 to -5.83 μm, all p < 0.05). Area under receiver operating characteristic curves of GC-IPL were generally higher than that of RNFL to discriminate AD and MCI from the controls.
  
  
  CONCLUSIONS
  Our data strengthens the link between retinal ganglion cell neuronal and optic nerve axonal loss with AD, and suggest that assessment of macular GC-IPL can be a test to detect neuronal injury in early AD and MCI.
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore.
authors.forename: Carol Yim-lui
authors.initials: CY
authors.lastname: Cheung
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
authors.forename: Yi Ting
authors.initials: YT
authors.lastname: Ong
authors.affiliation: Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Memory Aging and Cognition Centre, National University Health System, Singapore Department of Pharmacology, National University of Singapore, Singapore.
authors.forename: Saima
authors.initials: S
authors.lastname: Hilal
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore Memory Aging and Cognition Centre, National University Health System, Singapore.
authors.forename: M Kamran
authors.initials: MK
authors.lastname: Ikram
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Sally
authors.initials: S
authors.lastname: Low
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Yi Lin
authors.initials: YL
authors.lastname: Ong
authors.affiliation: Memory Aging and Cognition Centre, National University Health System, Singapore.
authors.forename: N
authors.initials: N
authors.lastname: Venketasubramanian
authors.affiliation: Department of Geriatric Medicine, Khoo Teck Puat Hospital, Singapore.
authors.forename: Philip
authors.initials: P
authors.lastname: Yap
authors.affiliation: Department of Geriatric Medicine, Singapore General Hospital, Singapore.
authors.forename: Dennis
authors.initials: D
authors.lastname: Seow
authors.affiliation: Memory Aging and Cognition Centre, National University Health System, Singapore Department of Pharmacology, National University of Singapore, Singapore.
authors.forename: Christopher Li Hsian
authors.initials: CL
authors.lastname: Chen
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore.
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence; D014795:Visual Pathways / Q000473:pathology
keywords: Alzheimer's disease; mild cognitive impairment; neurodegenerative disorder; optic nerve; retinal ganglion cell; spectral-domain optical coherence tomography