Retinal scans unveil potential links between eye health and systemic conditions, paving the way for early detection and preventive care. Explore how this innovative approach could revolutionise healthcare.

You see more with your eyes than just the information around you. They may also be an inward reflection. As a matter of fact, our eyes may detect conditions related to our health that we would not otherwise be aware of, such as blood pressure, diabetes, and genetic disorders. Because of this, scheduling regular eye examinations is even more crucial since your eye doctor will be privy to certain health indicators that you could be overlooking.

It's critical to maintain good eye health, particularly as we age when some visual alterations are normal. Here's a deeper look at the medical disorders that your eyes may reveal to you, sometimes even before you have symptoms.

Unexpected health issues that can be detected through eye exams

1. The eyes are important organs that keep an eye on neurons, connective tissues, and blood vessels. Aneurysms, brain tumours, blood, tissue, or skin cancers, diabetes, giant cell arteritis (GCA), heart disease, high blood pressure, high cholesterol, lupus, Lyme disease, medication toxicities, multiple sclerosis, myasthenia gravis, rheumatoid arthritis, sarcoidosis, STDs, sickle cell disease, Sjögren's syndrome, stroke, thyroid disease, vascular disease, and vitamin A deficiency are just a few of the conditions that can be found during an eye exam.
2. Aneurysms are ruptured or leaking cavities in the blood vessel wall that necessitate urgent medical attention. Increased intracranial pressure from brain tumours affects the optic nerve and may cause abnormalities in the eye. A thorough eye exam may also identify cancers of the skin, blood, or tissue.
3. Diabetes is characterised by yellow fluid or blood leaking from tiny blood vessels in the retina, while GCA is characterised by inflammation of medium-sized arteries affecting the neck, arms, and upper torso. A yellow or blue ring around the cornea and deposits in the retina's blood vessels are indicative of high cholesterol. While Lyme disease is a tick-borne illness that causes inflammation all throughout the body, lupus may also cause dry eyes and swelling in the white area of the eye.
4. Red, scaling eyelids, red eyes, itchy corneas, and conjunctivitis may all be symptoms of medication toxicity. While Myasthenia gravis is an autoimmune disease that causes muscles to weaken and tyre easily, multiple sclerosis may be a sign of inflammation in the optic nerve. A painful inflammation of the iris or coloured portion of the eye is caused by sarcoidosis, while red eyes and intense pain are common symptoms of rheumatoid arthritis.
5. Thyroid illness may result in dry eyes, impaired vision, or vision loss. Stroke can be caused by blockages or clots in the blood vessels of the retina. Both retinal and subconjunctival haemorrhages may cause vascular disease. Night blindness and dry eyes may result from a vitamin A deficiency.

Overview of new study findings

A phenotypic and genetic investigation linked thinner retinal layers to a vast variety of significant ailments, including heart and pulmonary conditions.

Every standard deviation of thinner photoreceptor segment layers was substantially linked to increased risks for the following disorders among many others:

• Heart failure that is not hypertensive but congestive: HR 1.25 (95% CI 1.12-1.39)
• Chronic airway blockage incident: HR 1.31 (95% CI 1.24-1.38)
• Heart attack: HR 1.17 (95% Confidence Interval 1.10-1.25)
• HR 1.47 (95% CI 1.30-1.65) for emphysema

According to Nazlee Zebardast, MD, MSc, of Harvard Medical School in Boston, and colleagues in Science Translational Medicineopens, those with alcoholic liver damage (β = -0.68, 95% CI -0.98 to -0.38) and those with prevalent multiple sclerosis had notably thinner ganglion cell complex layers (β = -1.12, 95% CI -1.37 to -0.87).

Both narrower ganglion cell complex layers at baseline (HR 1.12, 95% CI 1.07-1.18) and thinner photoreceptor segments at baseline were linked to death throughout a 10-year follow-up period, after adjusting for numerous covariates.

The results do not establish a clear causal relationship between illness and weaker retinal layers. Furthermore, it's uncertain how significant the findings are clinically. The study does, however, provide more insight into the relationships between retinal and systemic health, an area of research that has proven difficult to navigate.

Implications for clinical practice

Previous studies have connected systemic ageing variables and cardiovascular health to retinal phenotypes. The nine distinct retinal layers, which each represent distinct cell types in the retina and have various functional responsibilities, were further distinguished in this study by the researchers. These include several neuronal, vascular, and epithelial cell types.

According to working theory, the illness effects are represented by weaker retinal layers. For example, poor lung and heart health may shrink photoreceptor segments by reducing blood supply to their cells. Hypoxemia and restricted blood flow, which are often attributable to pulmonary or cardiovascular diseases, may readily harm photoreceptor cells, which are very sensitive.

Multiple sclerosis, epilepsy, and alcoholism may all lead to damage to the layers of retinal nerve fibres. Furthermore, drug use-related ocular neuropathies may cause nerve atrophy and degeneration across the retina over time, which thins the inner layer of the retina.

The current research adds to the fast-growing body of information about the connections between systemic and ocular health. Big data, artificial intelligence, and advanced retinal imaging have "supercharged" studies into possible linkages; the burgeoning discipline is now called "oculomics".

It seems natural that the eye may provide this window in various ways. The only such circulation that can be directly seen in live humans is the microvasculature of the retina. Furthermore, the retina's neural tissue is a direct outgrowth of the central nervous system. The current study successfully offers a treasure map for future oculomics research.

However, one must use caution since confounding variables may be at play in certain correlations. For instance, earlier research has shown alterations in the retina in schizophrenia patients. Nonetheless, these modifications can be brought on by the drugs used to treat the illness or by the condition's subsequent cardiometabolic consequences.

In order to conduct the study, researchers examined retinal layer thicknesses in 44,823 people from the U.K. Biobank using optical coherence tomography (OCT) pictures. The average age was 56.8, women made up 53.7% of the population, and all were of European ancestry.

In addition to ischemic heart disease, cardiac conduction disorders, type 1 and type 2 diabetes, ophthalmic and neurological manifestations of diabetes, pneumonia, chronic bronchitis, elevated HbA1c, resting heart rate, and serum triglycerides, the researchers discovered that thinner photoreceptor segments were associated with a number of other conditions.

To determine the usefulness of retinal OCT measures alone or in conjunction with current risk assessment techniques, further investigation is necessary. Our work also demonstrates how retinal imaging may be combined with genetic information, electronic health records, and other biomarkers to improve our knowledge of disease pathways and to guide risk management and prediction techniques.

An OCT machine may potentially be used for an unlimited number of scans at no extra cost, and a single scan takes less than a minute. It differs from an MRI or CT scan, which needs a large machine, electricity, etc.

We may even be able to forecast how certain circumstances may evolve in the future.

Disclaimer- The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of M3 India.

About the author of this article: Dr Monish Raut is a practising super specialist from New Delhi.