Evaluation of the chorioretinal thickness changes in Alzheimer's disease using spectral‐domain optical coherence tomography

BACKGROUND: To assess the chorioretinal thickness changes using spectral-domain optical coherence tomography (SD-OCT) and to evaluate the association between these structural changes and cognitive impairment in Alzheimer's disease (AD). DESIGN: Prospective, cross-sectional study PARTICIPANTS: Thirty-one eyes of 31 consecutive patients with AD and 30 eyes of 30 cognitively healthy age-matched control subjects were recruited METHODS: SD-OCT (RTVue-100) was used to measure the macular ganglion cell complex thickness (mGCC), outer retinal thickness (ORL), and the choroidal thickness (CT). Cognitive function was evaluated by Mini-Mental State examination (MMSE) on the same day of the optical examination. MAIN OUTCOME MEASURES: Chorioretinal thickness. RESULTS: The mGCC average, mGCC superior and mGCC inferior thicknesses of the AD group were significantly thinner than those of the controls (all, P < 0.05). No significant difference was found in the ORL thickness measurements between the two groups. Compared with control subjects, the CT measurements at all regions were significantly thinner in patients with AD than controls except CT measurement at 3.0 mm temporal to the fovea (P = 0.067). Significant correlations between the mGCC thickness measurements of the AD group and MMSE scores were observed. There was no significant correlation between the MMSE scores and the CT measurements (P > 0.05). CONCLUSIONS: Patients with AD had chorioretinal structural alterations. Retinal structural alterations were seen only in the inner layers. The reduction in mGCC thickness parameters were related to the severity of cognitive impairment in AD.