New Town: A white spot on the pupil of a child can be the first sign of cancer in the eye and medical consultation should be sought immediately because the disease is otherwise painless and hard to detect, doctors warn.

Parents should also be mindful of the child developing a squint, something that is often ignored because the condition usually corrects itself over time.

However, doctors said at a programme on Thursday, the squint can also be the first telltale sign of ocular cancer in children, which has an incidence of one in 18,000 and is not too uncommon.

"The most common ocular cancer is retinoblastoma (cancer of the retina) and it manifests in children mostly below five. The problem in detection is that the vision is affected slowly and children are mostly not able to express this to their parents," said Bikramjit P. Pal, ocular oncology specialist at Kamalnayan Bajaj Sankara Nethralaya in New Town.

He was speaking at a discussion on ocular oncology organised by the New Town hospital.

According to doctors, retinoblastoma is treated with laser rays and chemotherapy. Radiation is avoided as it exposes the child to the risk of developing other cancers.

If an eye has to be removed, focussed radiation is sometimes done to destroy the cancer cells that might remain after the surgery.

Ocular cancer affects the retina and might spread to the brain and bones if it remains undetected. "Once it spreads, it becomes difficult to save the patient," Pal said.

"As ocular cancer is not very common, valuable time is lost trying to convince the parents that their child had the disease," said Suchetana Mukherjee, deputy medical director, Sankara Nethralaya. "They often go to the wrong place for a second or third opinion and the disease keeps progressing."

Kamalnayan Bajaj Sankara Nethralaya has tied up with Tata Medical Center, which is just across the street, for administering chemotherapy to patients suffering from ocular cancer.

The disease can affect adults, too, but the incidence in India and other Asian countries varies between 0.2 and 0.4 in every 10 lakh adults, Pal said.

Doctors still advise everyone to get a retina test done at least once a year.