Introduction
Retinal nerve fiber layer (RNFL) degeneration is analogous to the severity of Alzheimer’s disease. RNFL thinning has been observed in early stages of dementia and a co-relation between Retinal thickness (RT) and decline of cognitive function has been previously established.
Objective
To assess the variation in RT and its association with clinical symptoms in AD patients.
Patients and Methods
96 AD patients with mild cognitive impairment (MCI) and dementia were included in the study.
Assessment
- Optical coherence tomography (OCT).
- Global cognitive function
- Neuropsychiatric symptoms
- Activities of daily living
Result
- According to the OCT, 54.17% had an abnormal RT while 45.83% had a normal RT.
- The average RT, the RT of the superior 1/2 quadrants and the RT of the inferior 1/2 quadrants of the right and left eyes were all notably decreased in the abnormal AD-RT group (p < 0.001).
- The average Ganglion cell complex thickness (GCCT), the GCCT of superior 1/2 quadrant, and the GCCT of the inferior 1/2 quadrant of left eye were all remarkably decreased in the abnormal AD-RT group (p < 0.05)
- The MMSE score in the abnormal AD-RT group was lower than in the normal AD-RT group (p < 0.01).
- The average RT and the RT of the superior 1/2 quadrant of the right eye were associated with the MMSE score; lower the RT value of the superior 1/2 quadrants of the right eye, the worse was the overall cognitive function.
- Critical visual delayed recall impairment was associated with the lower the RT value of the superior 1/2 quadrant of the right eye in patients with AD.
- Lower RT value of the right eye was linked to poor language function while lower RT of left eye was associated with worse the executive function.
- Attention was significantly impaired in abnormal AD-RT patients marked by longer time to complete the Trail Making Test A (TMT-A).
- RT was not related to depression, anxiety, apathy and agitation in AD patients.
- Higher ADL score was observed in the abnormal AD-RT group.
Conclusion
RT to be utilized as a marker in evaluating the cognitive decline of patients with AD as a lower RT indicated cognitive impairment.