Glaucoma Underdiagnosed in Patients With Wet AMD

Open-angle glaucoma (OAG), primary open-angle glaucoma (POAG), and suspected glaucoma are recognized at a “significantly” lower rate in patients who already have a diagnosis of exudative age-related macular degeneration (wet AMD), according to findings published in Eye (Lond.). This research uncovers a possible underdiagnosis of glaucoma in patients with wet AMD.

Because AMD often requires treatment for several years, prolonged fluctuations in intraocular pressures (IOP) for patients receiving repeated intravitreal injections may be a significant risk factor for glaucoma or its progression. Some studies show an increased rate of glaucoma among patients with wet AMD, according to researchers. However other studies show no significant relationship between glaucoma and AMD.

In this study, investigators looked at the rate of glaucoma in patients with exudative or non-exudative AMD and compared the rate with an age-matched reference group. The team also studied the rate of each glaucoma subtype in these groups by reviewing billing records.

During the study, patients older than age 55 diagnosed with AMD were identified from billing records from 2015 to 2018. Of the 3991 patients with AMD, 2 cohorts of 990 patients were created by randomly age-matching patients with exudative AMD with non-exudative AMD patients. Then, patients within each group were further classified by subtype and the severity of their disease. The team reviewed the charts of patients with AMD without glaucoma-related diagnoses to determine potential underdiagnosis. Researchers applied a set of broad clinical criteria, including IOPs of 22 mm Hg or greater, a cup-to-disc ratio (CDR) of 0.6 or greater, or CDR difference between eyes of at least 0.2.

The rate of diagnosed glaucoma was significantly lower in patients with wet AMD (6.06%) compared with patients with non-exudative AMD (8.99%, P =.04). Similarly, the rate of suspected glaucoma was significantly lower in the first group compared with the second (12.12% vs 18.48%, respectively, P <.001). More patients with wet AMD (13.94%, n=138) met clinical risk criteria compared with patients who had non-exudative AMD (6.97%, n=69, P <.001), according to the findings. When these at-risk patients were added to their respective groups, the rate of glaucoma, or its suspicion, became similar (χ2=1.24, P =.539). Researchers conclude that these findings strongly suggest that glaucoma-related conditions may be underdiagnosed in patients with exudative AMD.

This study had several limitations, including its use of retrospective analysis based on billing records supplemented by a chart review. A larger sample size and additional data are necessary for the validation of the current findings. Second, a study of billing records of diabetic macular edema patients showed that these patients could be accurately identified using only ICD diagnosis codes. However, no study has investigated the accuracy of the diagnosis of AMD or glaucoma based on a comparison of ICD-10 coding. Third, the study used a per-patient analysis over a per-eye analysis. Lastly, only patients older than 55 years were included in the study.

Reference

Mergen B, Ramsey DJ. Underdiagnosis of glaucoma in patients with exudative age-related macular degeneration. Eye (Lond). Published online February 3, 2021. doi:10.1038/s41433-021-01417-0.