Repeated injections for AMD increase glaucoma risk
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Researchers in Wheaton, Ill., reported that patients with age-related macular degeneration were more likely to develop glaucoma and its risk factor, ocular hypertension, when treated repeatedly and frequently with anti-VEGF intravitreal injections.
Data were collected from patients at the Wheaton Eye Clinic who had received at least one anti- VEGF injection between Jan. 1, 2005, and Dec. 31, 2012.
The researchers then limited the study to those who were correctly diagnosed with exudative AMD who had no history of bilateral injections, no history of glaucoma or ocular hypertension (OHT) before the first injection, and no diseases in the contralateral eye that would encroach on the diagnosis or treatment of glaucoma. Additionally, patients who had their last follow-up less than 30 days after injection were eliminated.
The 1,078 remaining subjects were analyzed for diagnosis of glaucoma through the examination of each patient’s clinical file. Twenty-three were eliminated because of their contralateral or bilateral diagnosis, leaving 1,055 subjects for statistical modeling of disease risk.
The researchers found that of 42 patients diagnosed with unilateral glaucoma or sustained OHT development, 40 (95.2%) developed the disease in their injected eye and not the contralateral eye.
According to the modeling, there was an increased risk for the development of glaucoma and OHT with high-frequency anti-VEGF injections over a 6-month period. The authors theorized that this may be “related to the process of the injections themselves, where the repeated injections of volume into the restricted space of the vitreous cavity create an immediate and substantial pressure imbalance between the vitreous cavity and the areas anterior to the lens that are filled with aqueous humor.”
The study also found that patients who had cataract surgery without or before the diagnosis of glaucoma or OHT were at a decreased risk to develop the disease, compared to patients who did not undergo the surgery. There was also a slightly higher risk of disease development for men in comparison to women. – by Kalie VanDewater
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Heather Jones, OD, FAAO
The authors of this retrospective chart review claim to show a significant increase in risk for glaucoma development and ocular hypertension in eyes receiving frequent intravitreal anti-VEGF injection, particularly in phakic eyes. While most patients developed elevated IOP in the first year or two after their first injection, for some it occurred after more than 4 years.
These findings could suggest the need for more frequent and sustained screening for the development of glaucoma in our AMD patients receiving intravitreal injections.
However, there are considerable design flaws that limit the applicability of the study. While patients with a pre-existing diagnosis of glaucoma or ocular hypertension were excluded from the study, glaucoma suspects were not. The interval between the last injection and follow-up IOP measurement was not described. Most notably, development of elevated IOP was the “event” that triggered the ultimate diagnosis of either glaucoma or ocular hypertension, yet the level of IOP that qualified as elevated was not defined. Further, the diagnosis of both glaucoma and ocular hypertension were defined only by the opinion of the managing glaucoma specialist. And, finally, it seems that the development of glaucomatous optic neuropathy with normal IOP measurements on follow-up would not have been considered.
While the results of this study suggest an association between frequent intravitreal anti-VEGF injections and elevated IOP after the immediate post-injection period, more rigorous investigation should be conducted before patterns of clinical practice change in a substantial way.
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