Changes in Ocular Biomarkers from Normal Cognitive Aging to Alzheimer's Disease: A Pilot Study

Pareena Chaitanuwong; Supharat Jariyakosol; Supanut Apinyawasisuk; Parima Hirunwiwatkul; Hathairat Lawanlattanagul; Solaphat Hemrungrojn; Yuda Chongpison

doi:10.2147/EB.S391608

Changes in Ocular Biomarkers from Normal Cognitive Aging to Alzheimer's Disease: A Pilot Study

Eye Brain. 2023 Mar 1:15:15-23. doi: 10.2147/EB.S391608. eCollection 2023.

Authors

Pareena Chaitanuwong^{1

2}, Supharat Jariyakosol^{3

4}, Supanut Apinyawasisuk^{3

4}, Parima Hirunwiwatkul^{3

4}, Hathairat Lawanlattanagul^{3

4}, Solaphat Hemrungrojn^{5

6}, Yuda Chongpison⁷

Affiliations

¹ Ophthalmology Department, Rajavithi Hospital, Ministry of Public Health, Bangkok, Thailand.
² Department of Ophthalmology, Faculty of Medicine, Rangsit University, Bangkok, Thailand.
³ Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
⁴ Ophthalmology Department, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand.
⁵ Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
⁶ Cognitive Fitness and Biopsychiatry Technology Research Unit, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
⁷ Biostatistics Excellence Center, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Abstract

Purpose: To identify ophthalmic findings in Alzheimer's type dementia (ATD) compared to normal subjects.

Patients and methods: This comparative descriptive study included participants from the institution's cognitive fitness center. Complete ophthalmic examinations were performed. Optical coherence tomography (OCT) and OCT angiography (OCTA) were used to analyze retinal thickness and vascular density. The Ocular Surface Disease Index (OSDI) score and tear breakup time (TBUT) were used to assess dry eye. The blink rate was counted by a well-trained observer. Cognitive function was evaluated using the Thai Mental State Examination (TMSE) score. Correlation analysis was performed to compare OCT, OCTA parameters, and TMSE.

Results: We included 24 ATD patients and 39 normal participants as a control group by age and sex-matched. The prevalence of dry eye using the Asia Dry Eye Society criteria was 15% and 13% in normal and ATD patients, respectively. The differences in OSDI scores, TBUT, and blink rate between the two groups were not statistically significant. The parafoveal and perifoveal macular thickness of the ATD group were significantly lower than that of the control group (p<0.01). All parameters of the vessel density of the ATD group were significantly lower than in the control group, including the whole macular vessel density (p<0.01), optic disc vessel density at the nerve head level (p<0.01), and optic disc vessel density at the radial peripapillary capillary level (p<0.05). After age adjustment, there were no statistically significant differences in all the OCT and OCTA parameters. There was a positive correlation between retinal thickness and vessel density in the macular and optic disc region and TMSE scores.

Conclusion: Perifoveal and parafoveal retinal thickness might be more sensitive than peripapillary RNFL thickness to detect neurodegenerative changes in patients with ATD. Macular thickness and vessel density reduction were also positively correlated with cognitive decline.

Keywords: Alzheimer; OCT; OCTA; TMSE; dry eye.