A drug which is widely prescribed for a bladder condition for decades worldwide,now appears to be toxic to the retina. This report has been given by a teamof Indian-origin doctors in the US.

Last year, after a preliminary report that Elmiron (pentosanpolysulfate sodium) might be associated with retinal damage, three ophthalmologists conducted a review of patients at Kaiser Permanente in northern California. They discovered that about one-quarter of patients with significant exposure to Elmiron indicated definite signs of eye damage.

This medication toxicity could cover-up as other known retinal conditions, such as age-related macular degeneration or pattern dystrophy.Robin A. Vora from Kaiser Permanente said that it is unfortunate having a patient with a chronic condition like interstitial cystitis and there is no cure or effective treatment.

These patients are puton these medications because it is assumed to have few side effects and few risks, and no one wants to think about it again. Year after year, the number of pills goes on increasing.

Interstitial cystitis can cause chronic pain in the bladder and pelvis area. Elmiron is the only FDA-approved pill to treat it and hence being prescribed in India too for several years. Hundreds of thousands of people have been exposed to the drug.

Last year, Nieraj Jain of Emory Eye Center in Atlanta, Georgia, stated that six patients who had been taking Elmiron for about 15 years had developed uncommon changes in their macula, the central part of the retina responsible for delivering clear, crisp, central vision. Dr. Jain and his colleagues raised a warning flag that long-term use of Elmiron might damage the retina.

Vora, Amar P. Patel, and Ronald Melles, ophthalmologists at Kaiser Permanente, noticed that warning and looked at their database of patients. They found almost 140 patients who had taken an average of 5,000 pills each over the course of 15 years. Out of those 140 patients, 91 patients agreed to visit for an eye examination. The doctors took meticulous images of the back of their eyes. Twenty-two of the 91 patients presented clear signs of drug toxicity.

The rate of toxicity increased with the amount of drug consumed, from 11 per cent of those taking 500 to 1,000 grams to 42 per cent of those taking 1,500 grams or more.

As it is unclear how much medication is too much, Dr Vora recommended patients who show no signs of toxicity to be screened for retina damage at least once a year. For those who did show some signs of damage, he recommended that they should speak with their urologists about discontinuing the medication.

The doctors said that if it is identifiedearly, the damage might be lessened by stopping the medication.

On Saturday, this research was presented at "AAO 2019", the annual meeting of the American Academy of Ophthalmology at Moscone Center in San Francisco.