IOP Increases Accelerate Macular Thinning in Primary Open-Angle Glaucoma

Intraocular pressure (IOP) increases accelerate macular thinning in the ganglion cell layer (GCL) and ganglion cell inner plexiform layer (GCIPL) in individuals with primary open-angle glaucoma (POAG), according to a study published in Ophthalmology Glaucoma. These macular thickness changes, which are detectable upon spectral domain-optical coherence tomography (SD-OCT) imaging, may serve as structural biomarkers to evaluate the efficacy of IOP-lowering treatments, the report suggests. 

Researchers performed a retrospective electronic medical records assessment of individuals with POAG (N=256; eyes, 451; mean age, 69.6 years; 50.4% women) who were evaluated at the Duke University Eye Center. Participants underwent macular SD-OCT assessment, and only those with 2 good quality scans (mean, 3.9 scans) and 6 months or more of follow-up (mean, 1.8 years) were included in the analysis. The team assessed how IOP increases accelerate macular thickness reductions over time.

Participants experienced mean GCL thinning of 0.220 µm per year and GCIPL thinning of 0.231 µm per year during the investigation. The report shows that IOP increases accelerate these changes — a 1mm Hg IOP increase was associated with an additional GCL and GCIPL thinning of 0.021 and 0.32 µm, respectively (P =.001 for both). 

 “[W]e demonstrated that even during a relatively short follow-up time, higher levels of mean IOP exerted a significant effect on progressive GCL and GCIPL loss in the macula as measured by SD OCT,” according to the researchers. “Because IOP is a well-established risk factor for the development and progression of glaucoma, this finding adds support to the use of macular SD OCT scans as a method for assessing structural damage in glaucoma and monitoring the efficacy of IOP-lowering treatments in slowing down progression of the disease.”

A subgroup analysis of participants with 5 or more SD-OCT scans (n=56; eyes, 104) revealed that 1 mm Hg IOP increases accelerate GCIPL slope a mean -0.053 µm per year (95% CI, -0.079 to -0.026 µm/year).

Study limitations include a lack of macular SD-OCT scans for a majority of patients in the electronic medical records database. 

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.