Age-related changes in the non-linear mechanical strain response of human peripapillary sclera

In glaucoma, the optic nerve head (ONH) is the site of damage to the retinal ganglion cell axons that transmit the visual information from the eye to the brain. Results of several randomized prospective trials showed that intraocular pressure (IOP), age1, increased optic disc cupping, corneal thickness, and African ancestry2 are independently associated with glaucomatous progression. All of these risk factors have a biologically plausible association with either the level of IOP, the severity of disease, or biomechanical properties of the ONH. Importantly, age is the only risk factor other than IOP that is independently associated with the onset and progression of glaucoma across all of the major prospective clinical trials conducted over the past twenty years. In addition, every population-based survey conducted to date has demonstrated a strong relationship between the prevalence of glaucoma with advancing age, despite almost no studies showing IOP changes with age. These findings indicate that the aging ONH becomes increasingly vulnerable to glaucomatous injury at similar levels of IOP.