Benefits persist when glaucoma treatment is stopped

Glaucoma patients who stop taking prostaglandins still experience a reduction in intraocular pressure (IOP) six weeks after they stop, according to new research.

The findings, which were presented at the American Glaucoma Society Annual Meeting, could have implications for medical and surgical decision making in the treatment of glaucoma, as well in the development of new beneficial drugs and devices.

Scientists in Canada found that the IOP of people who discontinued the drug remained significantly lower than the mean pre-treatment baseline pressure, although it was higher than in patients who continued with prostaglandin.

In a six-week study, researchers at Western University assessed 214 glaucoma patients who had been using prostaglandin analogues for more than six months.

Of this group, 124 were randomly chosen to discontinue the treatment, while the remaining 90 continued using the drug. From a baseline IOP of 26.6 mm Hg, the mean pressure fell to 14.5 mm Hg after the initial period of prostaglandin analogue use.

The researchers found the mean IOP of patients who stopped the treatment was 20.3 mm Hg after six weeks of not using the drug, meaning that they remained significantly below the pre-treatment baseline pressure.

Dr Sarwat Salim, who contributed to the research, said that the study could have widespread clinical implications.

Dr Salim commented: “If a patient is booked for cataract surgery, or cataract surgery and one of the minimally invasive glaucoma surgeries, and right afterward you see a mild reduction, not a significant reduction, in intraocular pressure, you don't really know if it's the surgery that did it or if it is the sustained effect of the medication.”

Moorfields Eye Hospital consultant ophthalmic surgeon, Professor Sir Peng Tee Khaw, who was not involved with the work, said that the results could pave the way for improved prostaglandin treatment for glaucoma.

He told OT: “It is fascinating to see that if we could induce a biological prostaglandin effect that was rather long-acting by using some of the more contemporary methods, such as gene therapy, [perhaps] this effect could be made to last many years.”

However, Professor Sir Peng Khaw noted: “The problem with this effect is that it is not reliable or predictable and of course there are patients whose pressure starts to rise very quickly after stopping prostaglandins and therefore [this effect] cannot be fully relied upon unless full data is obtained from the individual patient.”

The researchers will now carry out further work to establish why the effects of the drug were sustained for so long after treatment ended.

Image credit: Lynn Greyling