Chronic high BP may cause glaucoma

Scientists have discovered people who had chronic high bold pressure were at increased risk of developing glaucoma.

Glaucoma, the second leading cause of blindness in the world, is a condition that occurs when too much pressure builds up inside the eye. This excess pressure pushes back against blood trying to enter the eye resulting in vision loss.

These results suggest that doctors should consider a patient's blood pressure levels in managing the potentially blinding eye disorder.

Data gathered from large populations of glaucoma patients subsequently suggested that hypertension in young patients protects against the disorder, but is a risk factor in older patients.

One explanation of this phenomenon is that any benefit from high blood pressure counteracting high eye pressure is lost as damage to blood vessels-a consequence of hypertension-becomes more prevalent.

The authors tested this hypothesis by comparing the effect of acute (one hour) and chronic (four week) hypertension in lab rats with elevated eye pressure.

When they raised blood pressure for four weeks, the researchers didn't get the same protection against eye pressure elevation as in the [one hour] case, said author Bang Bui, PhD, of the University of Melbourne, Australia. This meant that having high blood pressure for a longer time had compromised the eye's capacity to cope with high eye pressure. It seemed that hypertension might damage the blood vessels in the eye so that they couldn't compensate for changes in blood flow when eye pressure increases.

This new understanding of the consequences of high blood pressure will help doctors treat patients with glaucoma. Instead of viewing hypertension as beneficial in the fight against the disorder, Bui suggests it should be identified as a risk factor. Further studies in this area might better inform how to treat patients with hypertension who also develop glaucoma.

The study is published in Investigative Ophthalmology and Visual Science (IOVS).