High Myopia and Glaucoma-Like Optic Neuropathy

Purpose: Previous population-based and hospital-based studies have shown an association between high myopia and higher prevalence of glaucomatous or glaucoma-like optic neuropathy (GON). Here we discuss potential factors associated with such a correlation. Design: Review. Methods: Findings from population-based and clinical investigations were combined with observations from light-microscopical examinations of human eyes. GON was defined by an abnormal shape of the neuroretinal rim as shown by a vessel kinking close to optic disc border in the inferior, superior, or nasal optic disc region. Results: The prevalence of GON increased (P < 0.001) beyond an axial length of 26.5mm or a myopic refractive error of similar to 8 diopters and reached up to 80% in eyes with an axial length >33 mm. It was associated with a larger optic disc and/or larger parapapillary delta zone. Histological factors potentially associated with the myopia-related increased GON prevalence were an elongation and thinning of the lamina cribrosa resulting in intra-lamina changes and a steepening of the translamina cribrosa pressure gradient; a lengthening and thinning of the peripapillary scleral flange which is the ophthalmoscopical equivalent of parapapillary delta zone and acts as the biomechanical anchor of the lamina cribrosa; and an increased distance of the peripapillary arterial circle of Zinn-Haller to the lamina cribrosa, due to the elongation of the peripapillary scleral flange. In addition to GON, a nonglaucomatous optic nerve damage may occur in the papillo-macular region due to a parapapillary gamma zone-associated lengthening of the retinal nerve fibers. Conclusions: In highly myopic eyes, one should be vigilant not to overlook GON.