Calcutta: Blood leakage in the retina of people with high blood pressure can lead to sudden loss of vision or permanent blindness if left untreated, doctors have said.

The condition, called retinal arterial macroaneurysm (RAM), can also lead to gradual loss of vision in the affected eye, depending on the area of the retina where the leakage has occurred.

"Seventy-five per cent of patients suffering from RAM have high blood pressure while 25 per cent are elderly people," Kshitiz Kumar, vitero retinal surgeon with Dr Agarwal's Eye Hospital said.

"While no precaution can be taken directly against RAM, if someone over 60 with high blood pressure suffers a sudden or steady loss of vision, he/she should consult a doctor immediately."

The initial treatment is non-invasive.

Laser beams are used to seal the leaking capillary in the retina.

The next part is invasive. It comprises inserting a mixture of a gas and air to get rid of the layer of blood.

"Once fresh leakage stops, the blood that remains in the jelly of the eye is flushed out by injecting a gas into the eye," Kumar said.

Pronob Bhattacharya, 67, from Kasba was baffled when he suddenly saw a yellow light streak across his eye leading to an instant loss of vision.

"In this case, the initial leak blotted out the vision and some of the leaked blood settled behind the retina," Kumar said.

Kumar was speaking at recent conference on the prevalence and treatment of RAM organised by Dr Agarwal's Eye Hospital, which has two centres in city.

Bhattacharya, who is on medication for high blood pressure for six years, lost his right vision in November and Kumar operated on him the next month.

"Now, my vision is almost like before. But it was a very scary experience when I suddenly lost vision in one eye," Bhattacharya said.

The disease is not uncommon and affects one in 9,000 people across the world, according to studies.