Eye Disorder

The sharpness of the vision is reduced especially in people who have a cataract, glaucoma, aged-related macular degeneration retinitis pigmentosa (RP), or Congenital Stationary Night Blindness (CSNB). RP and CSNB are the most common and severe hereditary retinal diseases that are associated with blindness. The visual pigment of rod photoreceptor cells, Rhodopsin is a member of the large family of G protein-coupled receptors. It is discovered that the mutation of a gene can result in biological consequences. Mutations in the genes for the visual pigment rhodonsin in rods cause Retinitis Pigmentosa (RP) and Congenital Stationary Night Blindness (CSNB) that have been shown biological consequences.

Retinitis Pigmentosa (RP) is the most common inherited disease that causes irreversible vision loss due to the degeneration of photoreceptor cells in the eye, rods and cones. As RP proceeds, the field of vision becomes extremely narrow and blindness often occurs. First rod cells undergo degeneration and the death of cone cells occur in the later stages of the disease. For example, according to the text 'An Introduction to Human Molecular Genetics', N244K gene mutation was found in patients with RP and the rod cell degeneration precedes the loss of cone cell. From the research from Dr.Cepko and his colleagues, the insulin /mTOR signaling pathway is a critical pathway for rod and cone photoreceptors. He states '...in regulating a number of aspects of cellular metabolism and its identification in a global expression assay of dying rod and cone photoreceptors suggested that there may be a link between the pathway and cell death.' They observed that the active mTOR was progressively reduced in the retinas and its depletion followed with cone cell death. Under other research by Dr.Miller, he states 'studied whether RIP-kinase-mediated necrosis is involved in the death of photoreceptor cells, finding for the first time that it is involved in cone degeneration and that a defieciency of RIP kinase reduced cone loss.' This suggests that treatment with a drug that inhibits RIP kinase significantly delayed cone cell death that die after degeneration. Therefore, even if RP started with the site in the rod, the cone cells die in response to death of rod cells- there are links between the pathways of rod and cone cells. The loss of the cone cells is the true impact of the disease and ultimately these mechanisms can develop therapeutic as treatment for vision loss in patients with retinitis pigmentosa.

While there is no loss of night vision in Retinitis Pigmentosa (RP), the rate of rod and cone degeneration is equal in CSNB. CSNB is a rare inherited retinal disorder that is characterized by impaired vision under low light conditions as a result of mutation in rod photoreceptor in the renita and also can be associated with other ocular problems such as high myopia. It is a genetically heterogenous disorder that can be