[Cognitive impairment and age-related eye pathology.]

In developed countries age-related macular degeneration (AMD) and glaucoma are the most common diseases of old age that cause irreversible blindness. Alzheimer's disease (AD), the most prevalent cause of dementia among older adults, is often associated with AMD and glaucoma. Features of AD include extracellular accumulation of β-amyloid (Aβ) and intracellular deposits of hyperphosphorylated forms of tau-protein. In addition, neuroinflammation and impaired iron metabolism in the brain are involved in the pathogenesis of AD, which ultimately leads to progressive neuronal death and dementia. It was found that the retina of patients with AMD also accumulates Aβ and iron, as well as Aβ and p-tau in retinal ganglion cells affected by glaucoma, and concomitant inflammation aggravates the pathological process. Patients with AD experience a marked decline in visual function which is thought to develop before the decline in cognitive function. Some are caused by degeneration of the visual cortex, others by retinal ganglion cell loss or retinal degeneration associated with AMD.