UPFRONT: Determining How to Extend Anti-VEGF Dosing


“In modern pharmacology it’s so clear that even if you have a fixed dose of a drug, the individuals respond very differently to one and the same dose.” — Arvid Carlsson, MD, PhD

Recent anti-VEGF real-world and randomized clinical studies all demonstrate a clear and undisputed fact — on average, fixed dosing works the best (at least in terms of preserving visual acuity). However, that doesn’t tell the full story. As Dr. Arvid Carlsson, the 2000 Nobel Prize winner in Medicine, correctly pointed out, some patients do not need or want that many injections. What is true in a population, may not be true in an individual. In CATT, there were patients who only required 1 injection over 24 months and did great. In the HARBOR study, we saw a similar variance in the number of injections required. So individualizing treatment is likely the best option.

But what is the best treatment regimen if we are abandoning fixed dosing? PRN? Treat and extend? PRN and extend? A combination? We will likely never truly know for sure, because everyone’s definition of a dry retina is different, and even in studies with treat and extend where one should not technically extend until the retina is dry, extension occurs with fluid present. This may not be as much of as an issue as we once thought, in particular in type 1 choroidal neovascularization, but in this case treat and extend was not being employed.

Arguably the best treatment regimen would treat a patient when fluid just starts to return. To figure this out would require daily monitoring that is not feasible in a physician’s office. However, recent technological advances have led to personalized monitoring that may allow us to realize the goal of treating only when we need to. The first foray into this arena was home visual acuity testing. Several years ago, I ran a study with Novartis looking at an iPhone-based program to test a patient’s vision and see if we could decrease the number of injections. The app was successful, and it is now FDA approved, but the study was not successful. Others have attempted to use similar iPhone-based programs with limited success because vision can often lag behind anatomic changes. A new entrant is described in this issue.

We also look at new devices that take the concept of home monitoring one step further. One that definitely got my attention was the idea of a portable home-based OCT device. The idea is not new, but the technology required to make it and, more importantly, the artificial intelligence software required to enable the device to make clinical decisions is now available. It will take a while before we see home OCT, but the promise of this for our patients, despite newer anti-VEGF drugs that last longer and implanted devices that offer the promise of 6 months or longer dosing, is undeniable. RP

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