Abstract
Purpose:
To evaluate the ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) thickness in patients with Alzheimer`s disease (AD) and mild cognitive impairment (MCI).
Methods:
We enrolled in the study 10 patients (20 eyes) with AD, 10 patients fulfilling diagnostic criteria for MCI and 10 age- and sex-matched cognitively normal healthy controls. Cases of age-related macular degeneration, glaucoma or any other conditions that can cause optic neuropathy were excluded. All the subjects underwent psychiatric examination, including the Mini-Mental State Examination (MMSE), and complete ophthalmological examination, comprising optical coherence tomography (OCT; RTVue-100 FD-OCT, Optovue Inc., USA) and scanning laser polarimetry (SLP; GDx VCC, Laser Diagnostic Technologies Inc., USA). OCT was used to obtain average GCC thickness, global and focal loss volume (GLV & FLV). RNFL thickness was measured in various segments using SLP and OCT. RNFL thickness standard deviation and Nerve fiber index were noted from SLP results.
Results:
There was no significant difference among the groups in terms of visual acuity, IOP, RNFL thickness (measured both by OCT and SLP) and focal loss volume of the ganglion cell complex. A significant decrease in average GCC thickness in patients with AD compared to the control group (Kruskal-Wallis test, p<0,01; post hoc Bonferroni-Dunn test, p=0.0001) and to the MCI group (p=0.0029) has been identified at the same time. The AD and control groups differed significantly in terms of GCC global loss volume (p=0.0494). Average GCC thickness in patients with MCI was thinner and GCC global and focal loss volume were higher than in control subjects, but not significant. Weak positive correlation of Average GCC thickness and MMSE results was observed (p=0.0217, r=0.523).
Conclusions:
Retinal degeneration was previously mentioned in postmortem eyes from patients affected with AD. Our data confirm the retinal involvement in Alzheimer`s disease, as reflected by loss of ganglion cells in the central retina. Further studies will clear up the role and contribution of dementia-associated neuro-degeneration in ganglion cell loss.
Keywords: 531 ganglion cells •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
610 nerve fiber layer