The blindness of age-related macular degeneration is linked to the build up of lipofuscin in cells, a hardy collection of metabolic waste products that the body cannot effectively break down. Lipofuscin accumulates to cause progressive failure of the cellular recycling and maintenance mechanisms known as autophagy - this is due to failing lysosomes, a part of the autophagic machinery which becomes increasingly clogged and bloated by lipofuscin.
Macular degeneration is one of the better known manifestations of this process, but it happens in long-lived cells throughout the body. The SENS proposals for rejuvenation therapies include the use of bacterial enzymes to break down the components of lipofusin, so as to restore autophagy and remove this contribution to degenerative aging. The open access research into autophagy and macular degeneration quoted below supports the SENS view on how best to proceed:
A new [study] changes our understanding of the pathogenesis of age-related macular degeneration (AMD). The researchers found that degenerative changes and loss of vision are caused by impaired function of the lysosomal clean-up mechanism, or autophagy, in the fundus of the eye. The results open new avenues for the treatment of the dry form of AMD, which currently lacks an efficient treatment.
AMD is a storage disease in which harmful protein accumulations develop behind the retina. These accumulations are indicative of the severity of the disease. As the disease progresses, retinal sensory cells in the central vision area are damaged, leading to loss of central vision. The cell biological mechanisms underlying protein accumulations remain largely unknown.
For the first time ever, the present study showed that AMD is associated with impaired lysosomal autophagy, which is an important clean-up mechanism of the fundus of the eye. This renders the cells in the fundus of the eye unable to dispose of old, deformed or otherwise faulty proteins, which, in turn, leads to the development of protein accumulations and loss of vision. The study can be regarded as a breakthrough, as the results change our understanding of the pathogenesis of AMD and also open new avenues for the treatment of the dry form of AMD. Drugs inhibiting the impairment of autophagy could possibly even stop the progression of AMD.