Peripapillary Atrophy (PPA) Indicates Optic Disc Stiffening in Primary Open Angle Glaucoma (POAG) without Statistically Elevated Intraocular Pressure (IOP)

Abstract

Purpose : PPA has been associated with progression of glaucomatous visual field loss. We investigated, as a biomarker of optic disc mechanical stiffness, the relationship between adduction-induced disc deformations and β-zone PPA in patients who have primary open angle glaucoma (POAG) with IOP never elevated above the statistical range typical of the healthy population.

Methods : The optic disc & peripapillary retina were imaged using infrared scanning laser ophthalmoscopy (Heidelberg Spectralis) in central gaze & 35° adduction in both eyes of 23 patients with POAG in whom IOP never exceeded 21 mmHg (mean age 65±13 (SD yrs)), & 19 age-matched normal subjects (age 62±9 yrs). Deformations of the optic disc & peripapillary retina, and location and extent of PPA were measured with ImageJ and analyzed with generalized estimating equations.

Results : During adduction, the nasal side of the optic disc was significantly less compressed in the temporal direction at 22±14μm (SD) in patients with POAG than in controls at 37±12μm (P=0.025). In eyes with POAG, β-zone PPA was most common in the inferotemporal quadrant (71% of eyes) and extended an average of 0.5 disc radius from the disc, whereas PPA was apparent in only 13% of controls. β-zone PPA was typically located diametrically opposite the disc region exhibiting the largest deformation during adduction. The radial extent of PPA in patients with POAG had a significant inverse linear correlation to the magnitude of disc deformation (P<0.001).

Conclusions : Patients with POAG without abnormally elevated IOP have subnormal temporal displacement of the nasal section of the optic disc during large angle adduction. This displacement corresponds inversely to PPA extent adjoining the temporal half of the optic nerve. Smaller optic disc deformation during large adduction in patients with POAG may potentially be a biomarker for pathological stiffening of disc and peripapillary tissues associated with glaucomatous optic neuropathy.

This is a 2020 ARVO Annual Meeting abstract.