Assessment of changes in the retina of patients with Alzheimer’s disease

Abstract

To assess the thickness of the retinal nerve fiber layer and its morphometric parameters using optical coherent tomography in Alzheimer's disease (AD). The study included 105 patients, among which 45 were with AD and 60 patients without AD (control group). Visual acuity of each eye was measured using Snellen chart, intraocular pressure according to Goldman, and cognitive state on the MMSE scale. All patients underwent optical coherence tomography. The average thickness of the nerve fibers of the retina in patients with AD was lower by 27.0%, in the temporal, upper and lower quadrants - by 24.0, 17.9 and 24.9%, respectively. The thickness in the nasal quadrant with AD was reduced by 15.4%. Excavation to diameter ratio, as well as vertical and horizontal excavation to diameter ratios on average exceeded the benchmark by 12.5%, 23.4% and 30.8% (p<0.05), respectively. There was a decrease in the size of the area of the neuroretinal belt and the area of the disk by an average of 28.5% (p<0.05) and 8.8%, respectively. The average thickness, the thickness in the upper and lower segments of the ganglion cell complex is reduced, the indices of focal and global loss of the volume of retinal ganglion cells complex are increased respectively by 1.7 (p<0.05) and 2.8 times (p<0.01). In patients with moderate AD, the thickness of retinal nerve fibers (RNFL) in the temporal, upper, and lower segments decreases significantly (p<0.001); a statistically significant (p<0.05) increase in the excavation to diameter ratio of the optic nerve head and a decrease in the area of the neuroretinal belt is observed; the increase in the indices of focal and global loss of the volume of ganglion cells complex is statistically significant (p<0.01).