Alzheimer Disease is Associated with Isotropic Ocular Enlargement

Recent studies have documented ocular changes in dementia patients, especially Alzheimer Disease (AD). In this study, we explored the change of eye size and eye shape in dementia, including AD patients. The eyeball volume and diameters were estimated via T1-weighted brain magnetic resonance (MR) images in the OASIS-3 database which included 83 AD, 247 non-AD dementiaand 336 normal-aging participants qualified for this study. After adjustment of age, sex, race, apolipoprotein E genotypes, anisotropic ratio and intracranial volume, we observed the eyeball volume of the AD group was significantly larger than both the normal control (6871mm3 vs 6415mm3, p < 0.001) and the non-AD dementia group (6871mm3 vs 6391 mm3, p < 0.001), but there was no difference between the non-AD dementia group and the normal control (6391 mm3 vs 6415mm3, p = 0.795). Similar results were observed for the axial, transverse and vertical length. No group differences were observed in the anisotropic ratio, indicating an isotropic volume increaseconsistent with previous changes induced by the ocular hypertension (OH), which suggested possible elevation of the intraocular pressure (IOP) in AD. In consideration of the recent findings in ocular changes of dementia, our findings emphasize routine eye examinations and eye cares for AD patients in the clinic.