title: The role of optical coherence tomography in Alzheimer's disease.
abstract: BACKGROUND
  Alzheimer's disease (AD) is the most common cause of dementia and its incidence is increasing worldwide along with population aging. Previous clinical and histologic studies suggest that the neurodegenerative process, which affects the brain, may also affect the retina of AD patients.
  
  
  METHODS
  Optical coherence tomography (OCT) is a non-invasive technology that acquires cross-sectional images of retinal structures allowing neural fundus integrity assessment. Several previous studies demonstrated that both peripapillary retinal nerve fiber layer and macular thickness measurements assessed by OCT were able to detect neuronal loss in AD. Moreover, recent advances in OCT technology, have allowed substantial enhancement in ultrastructural evaluation of the macula, enabling the assessment not only of full-thickness retinal measurements but also of inner retinal layers, which seems to be a promising approach, mainly regarding the assessment of retinal ganglion cell layer impairment in AD patients. Furthermore, retinal neuronal loss seems to correlate with cognitive impairment in AD, reinforcing the promising role of OCT in the clinical evaluation of these patients.
  
  
  CONCLUSIONS
  The purpose of this article is to review the main findings on OCT in AD patients, to discuss the role of this important diagnostic tool in these patients and how OCT technology may be useful in understanding morphological retinal changes in AD.
authors.affiliation: Department of Ophthalmology, School of Medicine, Juiz de Fora Eye Hospital, Federal University of Juiz de Fora, Av. Barão do Rio Branco, 4051, Bom Pastor, Juiz de Fora, MG 36021-630 Brazil ; Juiz de Fora Eye Hospital, Juiz de Fora, MG Brazil.
authors.forename: Leonardo Provetti
authors.initials: LP
authors.lastname: Cunha
authors.affiliation: Department of Neurology, School of Medicine, Federal University of Juiz de Fora, Juiz de Fora, Brazil.
authors.forename: Ana Laura Maciel
authors.initials: AL
authors.lastname: Almeida
authors.affiliation: Juiz de Fora Eye Hospital, Juiz de Fora, MG Brazil.
authors.forename: Luciana Virgínia Ferreira
authors.initials: LV
authors.lastname: Costa-Cunha
authors.affiliation: Juiz de Fora Eye Hospital, Juiz de Fora, MG Brazil.
authors.forename: Carolina Ferreira
authors.initials: CF
authors.lastname: Costa
authors.affiliation: Division of Ophthalmology, University of São Paulo Medical School, São Paulo, Brazil.
authors.forename: Mário L R
authors.initials: ML
authors.lastname: Monteiro
keywords: Alzheimer’s disease; Dementia; Ganglion cell layer; Macula; Mild cognitive impairment; Optic nerve; Optical coherence tomography; Retina; Retinal nerve fiber layer