Hyperspectral retinal imaging is a non-invasive imaging modality in which a series of images of the retina are captured using light of different wavelengths. The resulting "hypercube" of data provides a wealth of information about the retinal structure. Our group has developed evidence supporting a role for this technology in the detection of retinal amyloid beta in Alzheimer's disease. We are undertaking further studies to establish the role of this method in the assessment of people with dementia, or those at risk of Alzheimer's disease. In addition, we wish to test whether the approach may have value in other forms of dementia or neurodegenerative disease such as Parkinson's disease, Lewy-Body dementia or vascular dementia.

The retina is the inner part of the eye that is developmentally linked to the brain. Taking specialised pictures of the retina of the eye can reveal information about a person's eye health as well as their general health. Several research studies have shown that there are subtle differences in the retinas of people with dementia or neurodegenerative diseases including Alzheimer's disease and Parkinson's disease, compared to those without the disease. For example, in Alzheimer's disease, a protein amyloid beta builds up in the brain and in the retina of the eye. The build up of amyloid beta corresponds with the stage of dementia. Currently, measuring amyloid beta requires an expensive test, known as a PET scan, that can be difficult to access and involves exposure to radiation, which means that it cannot be repeated often. The other way to measure amyloid beta levels involves a collection of fluid (cerebrospinal fluid) from around the spinal cord. The development of a cheap, quick and easy test to detect the level of amyloid deposits would be a major advance for not only people with Alzheimer's disease but other forms of dementia and neurodegenerative diseases. It may allow easier monitoring of the progression of the disease and, importantly, monitoring of the effectiveness of new treatments to slow progression of the disease. Different changes occur in the retina in other types of brain diseases, suggesting that eye scans may help to detect a range of different neurodegenerative diseases.

Over the past few years, our research group has been studying a new type of camera, known as a hyperspectral camera, that can take images of the retina using many different colours (wavelengths) of light. It provides us with very detailed information about the structure of the retina that we cannot get using standard cameras. The eye scan is safe, quick and easy. We have shown that the eye scan can provide valuable information about people's eye and brain health. We now aim to test whether the scans can be used to find changes in the retina that are linked with dementia or neurodegenerative diseases. If changes are found, this could be used in future to help detect dementia or neurodegenerative diseases in the early stages or to monitor disease progression.

Inclusion Criteria:

1. Aged over 30 years.
2. Have dementia or a neurodegenerative disease such as Alzheimer's disease, Parkinson's disease, Lewy body dementia, Niemann-Pick type 2 or vascular dementia (age-matched and sex-matched controls will also be recruited).
3. With the exception of participants with Parkinson's disease and Lewy body disease, for whom clinical examination by a neurologist is sufficient to establish a clinical diagnosis of probable dementia with Lewy Body or probable Parkinson disease dementia, all participants must have previously undergone at least of one of the following tests to help to confirm a clinical diagnosis of dementia or neurodegenerative disease: genetic tests, blood biomarker tests (amyloid, tau, neurofilament light), a brain amyloid beta PET scan, or cerebrospinal fluid tests.
4. Have a minimum best corrected visual acuity level of 6/60 in both eyes and no major eye problems, such as advanced age-related macular degeneration, advanced glaucoma, or greater than moderate non-proliferative diabetic retinopathy.
5. Be willing to participate in the study and attend the Centre for Eye Research Australia.
6. Be accompanied by a friend or family member.

Exclusion Criteria:

1. Inability to provide informed consent
2. Ocular conditions preventing adequate retinal imaging (e.g., dense cataract, severe corneal opacity, vitreous haemorrhage)
3. Known contraindication to pharmacological pupil dilation
4. Any condition that, in the investigator's opinion, would compromise participant safety or image quality

The plan for sharing individual participant data (IPD) has not yet been finalised. This is a multi-modal imaging study involving large hyperspectral and ophthalmic imaging datasets, and decisions regarding data sharing will depend on completion of primary analyses, data governance requirements, and ethical approvals. The feasibility of appropriate de-identification and secure sharing mechanisms is under review.