A recent study determined that optic nerve head (ONH) prelaminar schisis could indicate glaucomatous deformation and reflect ongoing pathophysiological damage.
The cross-sectional study included 298 eyes of glaucoma suspects and patients and 88 eyes of healthy controls. Two masked reviewers independently graded the participants’ OCT scans for the presence of ONH prelaminar schisis on a four-point scale: zero (none) to three (severe).
The frequency and severity of ONH prelaminar schisis were greater in the glaucoma group than in the controls. Among the glaucoma group, 55.4% of eyes had no visible schisis, 23.8% had grade-one, 15.4% had grade-two and 5.4% had grade-three schisis. Among control eyes, 67.0% had grade-zero, 27.3% had grade-one, 5.7% had grade-two and none had grade-three schisis. The study noted that ONH schisis was more common in eyes with a thinner minimum rim width and deeper cup.
“The presence of a more severe ONH prelaminar schisis should alert clinicians to a higher risk of ongoing glaucomatous damage, as supported by the clear associations we report here for common structural parameters, such as ONH size (Bruch’s membrane opening area), neuroretinal rim width and cup depth,” the researchers wrote in their paper.
They point out that ONH schisis can also impact OCT diagnostic parameters as well as the clinical report, even in cases of “green disease” where the ONH rim thickness is within normal limits for the superior pole but the true rim thickness is extremely narrow.
The study authors suggest the need for more elaborate and robust segmentation capabilities to account for unusual anatomy, such as in the case of ONH prelaminar schisis. They’re hopeful that others can use their findings to better understand the spectrum of anatomical and pathological changes in glaucoma and recognize how prelaminar schisis can influence OCT results.
Lowry EA, Mansberger SL, Gardiner SK, et al. Association of optic nerve head prelaminar schisis with glaucoma. Am J Ophthalmol. November 6, 2020. [Epub ahead of print].