Optic Nerve Head Obliquity May Determine Treatment in Glaucoma-Associated PMRS

Differences in the orientation of optic nerve head obliquity are associated with differences in optical coherence tomography (OCT) and fluorescein angiography (FA) findings in eyes with glaucoma and papillomacular retinoschisis (PMRS), according to research published in Eye. 

Researchers performed a retrospective medical records review of 29 patients (eyes, 31) and stratified eyes according to optic nerve head margin shape (externally oblique: n=24 vs internally oblique: n=7 ). All study participants underwent OCT imaging, intraocular pressure (IOP) measurement, and biomicroscopic evaluation. The study’s objective was to determine whether differences in optic nerve head obliquity in the temporal margin affect lamina cribrosa defects and where the vitreous or other tractional forces are exerted. 

 A total of 29 eyes had normal tension glaucoma (NTG) and 2 eyes had primary open- angle glaucoma (POAG), the report shows. There were no significant differences between the groups for age, presenting best-corrected visual acuity (BCVA), presenting  IOP, axial length, mean deviation values, sex distribution, glaucoma type, and optic nerve head shape.

OCT imaging revealed a small schisis of the optic nerve fibers on the lamina cribrosa and on the externally oblique border tissue more often in patients with externally oblique optic nerve head margins compared with patients with internally oblique nerve head margins (P < 0.01 for both). The lamina cribrosa defect, beta zone, and gamma zone of the peripapillary atrophic area were also detected significantly more often in eyes with externally oblique margins (P ≤.03 for all). Retinal nerve fiber schisis around the optic nerve head, however, was more likely to be noted among participants with internally oblique optic nerve head margins.

The study authors highlight how differences in optic nerve head obliquity may affect treatment. 

“[T]he presence of a glaucoma-associated PMRS in [patients with externally oblique optic nerve head margins] may be related to [lamina cribrosa] defects, and the PMRS may extend from the internal side of the [optic nerve head],” according to the researchers. “We believe that the gradient of ocular and cerebrospinal pressures near the [lamina cribrosa] defect may influence the movement of fluid into PMRS. Thus, decreasing the ocular pressure may affect it if vitreous traction on the [optic nerve head] is not observed.”

The investigators recommend observation in individuals with internally oblique optic nerve head margins who do not demonstrate traction. 

Study limitations include a small sample size and retrospective nature.