What our eyes can reveal

The well-known saying about the eyes being the mirror of the soul is not so misguided, neither metaphorically or literally.

Not only do our eyes (how bright they are, their expression) reflect our state of mind, but a brief ophthalmological examination can reveal much more than myopia or astigmatism.

«It would not be the first time that a patient has come for a routine check-up and ends up being diagnosed with diabetes. The eyes are a bit like windows for the body.

We can see the world through them, but they also reflect illnesses in other parts of us, such as hypertension, hepatitis, cholesterol, tuberculosis, rheumatoid arthritis, Alzheimer's or a brain tumour,» explains Dr Javier Araiz, who is a retina specialist and the scientific director of the Clinical Surgical Ophthalmology Institute.

Some conditions can be detected with the naked eye (red or yellow eyes, specks, a lump of fat, for example) while others require a more thorough examination (multiple sclerosis, sexually transmitted diseases).

«As technology evolves, the eyes will be increasingly useful in diagnosing all types of illnesses because, as they are transparent, they require examination methods which are much less invasive than those in other parts of the body.»

«But even without technology it is possible to detect a series of health problems simply by looking at them,» says Barbara Pierscionek, deputy dean (Research and Innovation) of the Medical Technology Research Centre at the Anglia Ruskin University in the UK.

These are some of the warning signs to look out for:

A change in the colour of the sclera, normally known as the white of the eye, suggests that something isn't right, these specialists agree.

If an eye is red and bloodshot «it may indicate an excess of alcohol or drugs, but could also be due to allergies, conjunctivitis and irritation or infections that disappear in a few days in the majority of cases.

If the change of colour persists, it could be a sign of a more serious infection, an inflammation or a reaction to contact lenses and their fluids.

In extreme cases red eyes indicate glaucoma, an ocular illness which can lead to blindness,» adds Barbara Pierscionek, who is a specialist in optical technology.

A red spot in the eye is very noticeable, but most of the time this subconjunctival haemorrhage (rupture of a small localised blood vessel) disappears within a few days.

«However, it can also be a sign of high blood pressure, diabetes and coagulation disorders. In fact, some anticoagulant medication such as aspirin can cause a small bleed in the eye,» Dr Pierscionek says.

The problem comes if they start to bulge when that is something they didn't do before.

«The most evident cause is a problem with the thyroid gland, and that needs specialist attention. When just one eye is bulging, it could be due to an inury, an infection or, more rarely, a tumour behind the eye,» says Dr Pierscionek.

«These measurements can be used to evaluate the cognitive state of the patient,» she says.

Other symptoms include a loss of lateral vision, double vision and changes in the size of the pupil.