Optic Nerve Head Parameter May Detect Early Glaucomatous Damage

Bruch’s membrane opening-minimum rim area (BMO-MRA) decreases more rapidly in early glaucoma patients than peripapillary retinal nerve fiber layer thickness (RNFLT) and visual field index (VFI), according to a study in Journal of Glaucoma.

Researchers used a retrospective, cross-sectional study to compare decreases in BMO-MRA, RNFLT, and VFI. They evaluated 121 eyes of 121 patients (open-angle glaucoma; n = 73, healthy eyes; n = 48), using spectral domain optical coherence tomography to analyze the optic nerve head (ONH) and retinal nerve fiber layer, and a Humphrey Field Analyzer to obtain VFI. They estimated tipping points of RNFLT for VFI and BMO-MRA with broken-stick regression models, and performed polynomial regression analysis. 

The tipping point of the RNFLT for the VFI was 88.62 μm (95%CI: 79.59-97.65; P =.001], while the tipping point of the RNFLT for BMO-MRA was 60.00 μm (95% CI: 48.28- 71.72; P =.220). 

“Above the tipping point, BMO-MRA decreased with a decrease in the RNFLT (slope = 0.0135; 95% CI: 0.0115-0.0155; P <.001); below the tipping point, BMO-MRA did not decrease significantly (slope = 0.0002; 95% CI: -0.0177 to 0.0181; P =.983),” according to the investigators. “Polynomial regression analysis showed that with the progression of glaucoma, BMO-MRA decreased more rapidly, and this preceded a decrease in the RNFLT followed by a decrease in the VFI.”

Study limitations include a retrospective, cross-sectional nature and single center design. 

Reference

Choi HS, Joo CW, Park SP, Na KI. A decrease in Bruch’s membrane opening-minimum rim area precedes decreased retinal nerve fiber layer thickness and visual field loss in glaucoma. J Glaucoma. 2021;30(12):1033-1038. doi:10.1097/IJG.0000000000001947