Significant investments will continue to advance retinal disease field
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The intravitreal injection of an anti-VEGF, a corticosteroid or a complement inhibitor for the treatment of potentially blinding retinal disease is today the most common procedure performed by an ophthalmologist.
We will approach 8 million intravitreal injections in 2023 and may hit 10 million by 2025.
There are about 1.75 million Americans with neovascular age-related macular degeneration, another 1.75 million with geographic atrophy, about 750,000 with diabetic macular edema and another 900,000 with retinal vein occlusion. One review article reported that just more than 3,000 U.S. ophthalmologists perform intravitreal injections, with two-thirds being fellowship-trained retina specialists and one-third comprehensive ophthalmologists.
At present, in ophthalmology residency training programs, an intravitreal injection has replaced cataract surgery as the most frequent procedure performed. This leads me to predict that by 2030, comprehensive ophthalmologists will perform at least half the U.S. intravitreal injections.
According to the American Academy of Ophthalmology IRIS Registry, the typical patient presenting for an intravitreal injection is 81 years old. Sixty-five percent of patients are women, and 35% are men. The typical presenting visual acuity is 20/80. Most patients treated with monthly injections for neovascular AMD and DME achieve a 15 letter, or three line, improvement in visual acuity. That means a 20/50 visual acuity outcome is a reasonable expectation for the patient presenting with a 20/80 pre-injection visual acuity. Many patients now receive intravitreal injections at a far better visual acuity than 20/80, and it is possible to restore 20/20 vision for many patients.
The FDA clinical trials used monthly intravitreal injections, and the global data still support this approach, but few patients and their families accept the burden and cost of monthly intravitreal injections for long. This has led to the adoption of so-called as-needed and treat-and-extend protocols, which reduce the average number of annual injections from 11 to 12 per year to five to six per year.
We now have 10-year data for anti-VEGF therapy for neovascular AMD, and there is good news and bad news to report. Most patients who receive the average of five to six injections per year find their visual acuity returns toward baseline after 10 years of treatment. So, a 20/80 patient who improves to 20/40 or 20/50 after 1 to 2 years of therapy is back to 20/80 at 10 years. The untreated patient would of course be far worse at 10 years after diagnosis, likely 20/200 or worse, but the early visual acuity gains are often not retained for a lifetime. On the good news side, most patients and their eyes tolerate a decade of injections well. According to several studies I reviewed, the incidence of geographic atrophy is not higher with long-term anti-VEGF therapy, and there is no evidence of increased mortality. Secondary glaucoma, hemorrhage, retinal tear/retinal detachment and even infectious endophthalmitis can occur but are rare and manageable.
Significant human and financial capital is being invested in several promising strategies to reduce the burden on patients, providers and payers by decreasing the frequency of intravitreal injections. These include the application of oral, topical or injectable adjunct pharmaceutical agents that may retard disease progression or extend the effect of each injection; the use of higher concentrations of drug; extended drug release devices, formulations or cell therapy; and in the longer term, the application of gene therapy to induce a native cell in the eye to generate a lifetime of active therapeutic agent.
Without a doubt, intravitreal injections for the treatment of several once-untreatable blinding retinal diseases represent another modern-day miracle. We can expect many more advances in this field over the next decade as it continues to attract significant investment.
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