Optic nerve head (ONH) prelaminar schisis could be a potential sign of glaucomatous deformation, showing ongoing pathophysiological damage, according to a study published in the American Journal of Ophthalmology.
The cross-sectional study was designed to determine the association of ONH prelaminar schisis with glaucoma and its severity using optical coherence tomography (OCT) in 298 eyes of 150 patients with glaucoma, or who were glaucoma suspects, compared with 88 eyes of 44 health controls.
OCT scans included 24 radial B-scans of 768 A-lines spanning 15˚, centered on the ONH. The scans were independently graded by 2 reviewers who were masked to all clinical, demographic, and ocular information. They looked for the presence of ONH prelaminar schisis using a 4-point scale: 0 (none) to 3 (severe).
They discovered that ONH prelaminar schisis frequency and severity were greater in glaucoma/glaucoma suspect cases than in healthy controls (P =.009). In the glaucoma and glaucoma suspect group, 165 eyes (55.4%) had no visible schisis (grade-0), 71 (23.8%) had grade-1, 46 (15.4%) had grade-2, and 16 (5.4%) had grade-3 schisis. In healthy control eyes, 59 (67.0%) had grade-0, 24 (27.3%) had grade-1, 5 (5.7%) had grade-2, and none had grade-3.
In addition, in the glaucoma/glaucoma suspect group, ONH prelaminar schisis was more common in those eyes that had thinner minimum rim width and a deeper cup. ONH prelaminar schisis “can impact OCT image segmentation and diagnostic parameters, resulting in substantial overestimation of the true rim tissue thickness and underestimation of cup depth,” the investigators report.
“We found that the ONH prelaminar schisis sign was detected more frequently in OCT scans of glaucomatous eyes compared to healthy control eyes and that its presence and severity are associated with common OCT metrics related to increased risk, ONH deformation and structural damage in glaucoma, such as larger ONH size, thinner neuro-retinal rim width and greater cup depth,” they report.
Limitations of the study include that the cases studied were nearly all White, the grading scale used was “subjective and mostly qualitative,” and the glaucoma/glaucoma suspect group had “relatively few” cases of advanced glaucoma. Also, the healthy control group was “a relatively small sample of only 88 eyes of 44 individuals.”
Disclosure: Several study authors declared affiliations with industry. Please see the original reference for a full list of authors’ disclosures.
Lowry EA, Mansberger SL, Gardiner SK, et al. Association of optic nerve head prelaminar schisis with glaucoma. Am J Ophthalmol. Published online November 5, 2020. doi: 10.1016/j.ajo.2020.10.021