Do Glaucoma Staging Systems Underestimate the Severity of Macular Damage?
JAMA Ophthalmology, February 2019
Although recent studies have found that loss of macular function is more common in early glaucoma than originally thought, 24-2 and 30-2 standard automated perimetry (SAP) tests may routinely miss macular damage in the central 10 degrees of the visual field. This can lead to underestimation of glaucoma severity. In a cross-sectional study, de Moraes et al. demonstrated that most participants with glaucoma and 24-2 mean deviation (MD) better than ‒6 dB were classified by 24-2 and 30-2 SAP as having no or early-stage defects despite matching evidence of macular damage. The research was conducted at a New York glaucoma referral center and included 57 eyes of 57 participants with confirmed glaucoma (mean age, 57 years; 57% women). Macular damage was defined by 10-2 SAP and spectral-domain optical coherence tomography (SD-OCT) evidence of retinal ganglion cells plus inner plexiform layer probability maps.
Findings of glaucoma staging according to Hodapp-Parrish-Anderson (HPA) criteria, visual field index (VFI), and the Brusini Glaucoma Staging System 2 were then compared with visual field and SD-OCT results.
Forty-eight (84%) of the 57 eyes were confirmed to have macular damage. For the affected eyes, the mean (standard deviation [SD]) of the 24-2 MD was ‒2.5 (1.8); the mean (SD) of the 10-2 MD was ‒3.0 (2.4) dB; and the mean (SD) of the VFI was 94.2% (4.5%). In contrast, according to the HPA criteria, VFI, and Brusini systems, early defects were apparent in 70%, 81%, and 68% of the eyes that had macular damage, respectively.
The authors’ observations suggest that glaucoma staging systems based exclusively on 24-2 or 30-2 visual fields risk underestimating disease presence, location, and extent; moreover, they also may result in suboptimal care that ultimately may affect patients’ visual-related quality of life. If these results are confirmed and found to be generalizable to other patients, the authors would advocate using at least a 10-2 visual field and high-resolution macular SD-OCT scans in the classification of glaucoma.
The original article can be found here.