Of further importance for the maintenance of the retinal tissue are metalloproteases and their inhibitors. Metalloproteases are proteins which destroy or (better) digest proteins. During the night the photoreceptor outer segments shed about 1000 discs from their tips which then are ingested by the RPE and digested in the RPE lysosomes.
On remodelling a tissue these functions are established by the tissue cells itself.
To establish a controlled digestion of a tissue Tissue Inhibitors of Metalloproteases (TIMP) are active. One of these Tissue Inhibitors of Metalloproteases TIMP3 is known to be involved in Sorsby's Fundus Dystrophy (SFD) (3).