Comparison of optic disc morphology of optic nerve atrophy between compressive optic neuropathy and glaucomatous optic neuropathy

Abstract

Objectives: To compare the optic nerve head (ONH) structure between compressive optic neuropathy (CON) and glaucomatous optic neuropathy (GON), and to determine whether selected ONH quantitative parameters effectively discriminate between GON and CON, especially CON cases presenting with a glaucoma-like disc.

Methods: We prospectively assessed 34 patients with CON, 34 age-matched patients with moderate or severe GON, and 34 age-matched healthy control subjects. The quantitative parameters of ONH structure were compared using the Heidelberg Retina Tomograph 2 (HRT2) and Spectralis optical coherence tomography with an enhanced depth imaging method.

Results: The mean and maximum cup depths of CON were significantly smaller than those with GON (P < 0.001 and P < 0.001, respectively). The distance between Bruch's membrane opening and anterior surface of the lamina cribrosa (BMO-anterior LC) of CON was also significantly smaller than that of glaucoma but was similar to that of the healthy group (P < 0.001 and P = 0.47, respectively). Based on Moorfields regression analysis of the glaucoma classification of HRT2, 15 eyes with CON were classified with a glaucoma-like disc. The cup/disc area ratio did not differ between cases of CON with a glaucoma-like disc and cases of GON (P = 0.16), but the BMO-anterior LC and mean and maximum cup depths of CON cases with a glaucoma-like disc were smaller than those in GON (P = 0.005, P = 0.003, and P = 0.001, respectively).

Conclusions: Measurements of the cup depths and the LC depth had good ability to differentiate between CON with a glaucoma-like disc and glaucoma. There was no laminar remodeling detected by laminar surface position in the patients with CON compared to those with GON.

Figure 1. Optic nerve head quantitative parameters measured with enhanced depth imaging optical coherence tomography (OCT).

A radial OCT scans at the optic disc were obtained. White arrowheads show Bruch's membrane opening (BMO). Dotted line shows BMO reference plane. Black arrowhead shows the anterior surface of the lamina cribrosa (LC). The distance between BMO reference plane and anterior LC (α), prelamina tissue thickness (β) at the center of BMO reference plane, and the diameters of the BMOs (γ) are also indicated.

Figure 2. Representative case of eye with glaucoma.

A fundus photograph (A) shows a glaucomatous disc with enlarged optic disc cupping and upper rim loss. A vertical OCT scan (B) shows a distance of 406 µm between Bruch's membrane opening reference line and the anterior lamina cribrosa (α). A circular OCT (C) scan shows thinning of the circumpapillary retinal nerve fiber layer (58 µm).

Figure 3. Representative case of eye with compressive optic neuropathy caused by a meningioma.

A fundus photograph (A) shows optic nerve atrophy with pallor and enlarged optic disc cupping. A vertical OCT (B) scan shows a distance of 165 µm between Bruch's membrane opening reference line and the anterior lamina cribrosa (α). A circular OCT (C) scan shows severe thinning of the circumpapillary retinal nerve fiber layer (33 µm).