Abstract:
Alzheimer’s Disease (AD) is a progressive neurodegenerative disease characterized by the
accumulation of amyloid beta (a-beta) protein and hyperphosphorylation of tau protein in brain
and its peripheral regions. It is the leading cause of dementia worldwide which only worsens with
time. An extensive body of research suggests that the disease onset is triggered at least 15 to 20
years prior to the appearance of any initial symptoms. There is no cure so far and the treatment
lines only deal with slowing down the process of neurodegeneration. Owing to these facts, research
paradigms are shifting towards early diagnosis of AD to prevent the irreversible neurodegenerative
damage. A growing body of researchers is working on the use of ocular organelles for the early
assessment of AD. Retina shares its embryonic origin with brain and research suggests that protein
accumulation in brain as well as retina runs parallel in the patients. Lens has also been reported to
be associated with providing a window towards any change related to neurodegenerative diseases.
The contraction and dilation of iris are also being investigated as biomarkers for AD. The existing
techniques have incorporated the use of MRIs, PET scans, OCT and other brain imaging
techniques which are expensive and detect the disease indirectly. The techniques are although
sensitive but do not specifically target the disease or disease stage. To rule out these factors, a
robust, cheaper and direct technique is required which turns out to be specific, selective and
sensitive at the same time. IR light has penetration power up to retina and it is safely being used
in biometric identification using retinal scanning. Protein accumulation in retina has been
confirmed by literature and it is hypothesized that more is the accumulation of protein in retina,
more is the absorption of light and vice versa. A difference in incident and reflected light can
precisely detect disease and disease stage. This study focuses on the use of infrared (IR) light for
the investigation of a-beta stacks in patients when they are in pre-clinical stage of the disease.
