Eye Retina Becomes Window to Detect Heart and Lung Diseases

A research team led by Professor Nazlee Zebardast, a Harvard Medical School ophthalmologist, announced that the thinner the photoreceptor layer of the retina, the greater the correlation with heart and lung diseases, according to a report by medical news portal MedPage Today on the 30th.

The research team analyzed Optical Coherence Tomography (OCT) images of the eyes of 44,823 individuals (average age 56.8, 53.7% female) from the UK Biobank database and found this correlation.

The team conducted the research by differentiating the nine different layers of the retina, each with different functions and containing different types of nerve cells, vascular cells, and endothelial cells.

The team found that for every standard deviation decrease in the thickness of the photoreceptor layer of the retina, the risk of non-hypertensive congestive heart failure increases by 25%, chronic obstructive pulmonary disease by 31%, myocardial infarction by 17%, and lung cancer by 47%.

The research team also found that those currently suffering from multiple sclerosis or alcoholic liver disease have a thinner retinal ganglion cell complex layer.

A decrease in the thickness of the photoreceptor layer of the retina was also associated with ischemic heart disease, electrocardiogram disorder, type 1 and type 2 diabetes, pneumonia, chronic bronchitis, increased resting heart rate, and increased blood triglycerides.

Considering confounding variables, the analysis made that if the thickness of the photoreceptor layer of the retina decreases, the risk of death within the next 10 years increases by 16%, and if the thickness of the retinal ganglion cell complex layer decreases, it increases by 12%.

The reason for this is that if heart and lung function is not good, the blood flow into the cells in the photoreceptor layer of the retina can be damaged, which can reduce the thickness of the retina layer, the research team explained.

Multiple sclerosis, epilepsy, and alcohol use disorder can damage the nerve fiber layer of the retina, and drug use disorder can also lead to optic neuropathy over time, which can lead to retinal nerve degeneration and atrophy, and thinning of the inner layer of the retina, the research team said.

These results do not provide direct evidence of a correlation between the thickness of the retinal layer and heart and lung diseases, but they do show a correlation between the retina and overall health, the research team explained.

The research team emphasized that they have recently realized that a lot of information about diseases can be obtained from unexpected retina images and this information can be used to help prevent diseases through follow-up examinations.

In response to these research results, Dr. Piers Keen of Moorfields Eye Hospital in London explained that the microvessels of the retina are the only circulatory system in the human body that can be directly visualized, and therefore the retinal nerve tissue is an extension of the central nervous system.

However, he added that some of the associations between the retina and physical health may be due to confounding variables such as drugs used to treat other diseases or secondary effects of cardiac metabolism.

The results of this study were published in the latest issue of the American scientific journal, *Science Translational Medicine*.