Today, Alzheimer's disease and Parkinson's disease, which are diseases of the brain, and glaucoma and macular degeneration (yellow spot disease), which are ocular diseases, are described as progressive (neuro-degenerative) disorders of the nerve tissues. Studies have been undertaken to investigate their shared characteristics and important information has been discovered. The OCT examination used for the diagnosis and treatment of glaucoma and yellow spot disease is now used for Alzheimer's and Parkinson's disease as well. OCT provides diagnostic results in detailed eye examinations (for glaucoma, yellow spot disease etc.) and reveals very specific findings in conditions like Alzheimer's-Parkinson's disease and mildly impaired consciousness. Such specific findings are characterized by damaging and thinning in specific regions of either the retina or optic nerve fibers. Losses in nerve fibers are significant in the early diagnosis of Alzheimer's and Parkinson's disease. Nerve fiber thinning can be identified by OCT before the brain's regions for memory, movement etc. are damaged, allowing early diagnosis and treatment. Scanning of the retina and optic nerve fibers by OCT, a short and easy imaging method, in people with certain complaints or familial history of Alzheimer's and Parkinson's disease plays a major role in early diagnosis of the disease.

Diagnosis and close follow up of treatment with a retinal examination (FAF and OCT) is important for success. Retinal examination allows early diagnosis. Treatments have been started to prevent progression in patients diagnosed at an early stage. Because of genetic factors, people with a familial history of Alzheimer's and Parkinson's disease should have regular eye examinations after the age of 50.