The conventional wisdom on glaucoma is that, as IOP is the only modifiable risk factor of the disease, it must also be the most reliable bellwether of glaucomatous damage. However, as most glaucoma specialists will tell you, only monitoring IOP will provide an incomplete picture. Some glaucoma patients with low IOP may continue to progress. New research from Stanford University now confirms the most effective way of slowing the progression of glaucoma in a patient with low IOP is to lower the IOP further, sometimes to single digit levels, which is most often achievable with trabeculectomy, according to the investigators.

In a wide-ranging review of studies and clinical trials, researchers in Palo Alto, CA, have found that glaucoma patients require a more comprehensive testing protocol than merely IOP monitoring to establish progression. Their research asserts that large randomized clinical trials demonstrate a “tremendous variability” in visual field testing, and that greater variability can indicate disease progression, even when IOP remains low. Establishing visual fields is necessary before making any therapeutic advancements, the research suggests.

The study also advises clinicians to take multiple factors into account. “When it comes to optic nerve preservation or rescue, there is nothing magical about 12mm Hg and the emphasis on averages vs. individuals has clouded, rather than enlightened, the glaucoma therapeutic landscape,” the article states. “Experienced practitioners are aware that some individuals who are going blind from glaucoma at IOPs of 12mm Hg may stabilize and even improve if the IOP is reduced to single digits while other patients with similar disease severity at the time of diagnosis may do just fine with IOP measurements of 18mm Hg or higher.”

In addition to trabeculectomy, the researchers point to laser trabeculoplasty as a useful therapy option for patients whose IOP remains low while their glaucoma worsens. “Laser trabeculoplasty is efficacious, reducing the medication burden by 27% to 41% and the IOP by 11% to 22% to a final mean IOP of just over 12mm Hg.”

Wang S, Singh K. Management of the glaucoma patient progressing at low normal intraocular pressure. Curr Opin Ophthalmol. December 27, 2019. [Epub ahead of print].