Our eyes could reveal the status of our health and help doctors predict if we have any life threatening disease.
Conventional vision tests reveal eyesight abnormalities, such as macular degeneration.
But according to professor Emanuel Rosen, of Rosen Eye Associates, Manchester, a test of retina can identify early signs of conditions such as heart disease, cancer and diabetes, thanks to its superior image, reported online edition of Daily Mail.
The new eye test by an upgraded 'ophthalmoscope' a traditional instrument used to examine the retina and vitreous takes only three minutes and can help doctors diagnose life-threatening disease, it said.
The eye is very much an early warning post since its blood vessels allow us to see a mini-version of the body's circulatory system before the patient experiences symptoms, explained professor Rosen.
For example, if there are narrow arteries in the eye's blood vessels, it is likely that person has thinning arteries elsewhere, Rosen said.
Many other potentially fatal diseases can be first detected in the eye.
Leukaemia can start with a small haemorrhage in the eye, leading to leaking blood vessels. This symptom is also linked to diabetes, which, if untreated, can lead to blindness.
A swelling of the optic nerve and splashes of blood on the retina may be an early warning of a brain tumor.
A swollen, pale optic nerve could be a symptom of multiple sclerosis. And high blood pressure will cause blood vessels to burst and haemorrhages to form in the retina.
Professor Rosen's patients have included a woman whose breast cancer was diagnosed after he had examined her eyes. The test revealed swollen areas at the back of the eye, a sign of secondary cancer tumors.
The retina is the light-sensitive part of the eye on which images are produced.
Along with the optic nerve, it is linked to the brain and is therefore part of the central nervous system. So any changes in the retina can reflect problems elsewhere in the body, the researcher said.