How a tool for brain tumour surgery is sparing many people’s sight
NEW DELHI: The gamma knife, a radiation treatment tool that is often used to treat brain tumours, is now being used to treat malignant ocular tumours.
Instead of using a small carrier containing radioactive “seeds” (known as a plaque) placed on the outside of the eyeball over the tumour to deliver radiation, this device uses advanced imaging and computer software to deliver an intense radiation dose to the tumour while sparing the surrounding tissues.
Dr. Bhavna Chawla, an ophthalmology professor at AIIMS Delhi, claims that the new approach will better maintain eyesight while eliminating cancer cells. The Gamma Knife has previously been used for radiation treatment in 15 cases of choroidal melanoma.
“It is a significant accomplishment that 13 out of the 15 patients who received radiation therapy using the Gamma Knife at our hospital in the last 2.5 years were able to maintain their vision,” she said.
A malignant tumour that affects the choroid, a small layer of tissue that sits between the retina and the sclera, the white outer layer of the eye, is known as choroidal melanoma. According to Dr. Chawla, plaque therapy—an intrusive procedure—is the standard treatment for this uncommon kind of cancer.
“We have to do a little operation to implant the plaque, which is a tiny carrier filled with radioactive “seeds,” outside the eyeball above the tumour. A second procedure is required to remove the plaques after the administration of the radiation dose. It increases the likelihood of harming the optic nerve and surrounding tissues, which lowers the likelihood of eyesight preservation. The doctor from AIIMS said that using the Gamma knife technology is probably going to enhance the results.
According to Dr. Deepak Agrawal, a professor of neurosurgery at AIIMS Delhi, the Gamma Knife instrument has been used to treat brain lesions and tumours since the late 1990s. We have just begun investigating its use for malignant ocular tumours. “The outcomes have been promising,” he said. AIIMS charges Rs 75,000 for follow-up MRIs and radiation treatment using the Gamma Knife instrument.
