Glaucoma neurodegeneration and myopia

Beyond a cut-off value of approximately 26.5mm, the prevalence of glaucomatous or glaucoma-like optic neuropathy (GON) increases with longer axial length. In a hospital-based study, the prevalence of GON was 42% in eyes with an axial length of ≥30mm. Myopia-associated histological changes potentially associated with the increased GON prevalence are an elongation and thinning of the lamina cribrosa and peripapillary scleral flange. Correspondingly, clinical parameters associated with an increased GON prevalence were an enlargement of the optic disc and parapapillary delta zone. In addition to GON, a non-glaucomatous optic nerve damage can occur in highly myopic eyes, potentially due to a parapapillary gamma zone-associated lengthening of the retinal nerve fibers in the papillo-macular bundle. Clinically, GON and non-glaucomatous optic neuropathy should be ruled out in any highly myopic eye, in particular in those with a large optic disc, gamma zone and delta zone.