New Observation on the Role of Rhodopsin and Retinal Degenerative Diseases

New observation on the behavior between rhodopsin and photoreceptor cells could help explain retinal degenerative diseases and find new ways to treat blindness.

Retinal degenerative diseases refers to diseases that causes the retina, the light-sensitive layer of tissue, lining the inner surface of the eye, to deteriorate. As it deteriorates, cells of the retina starts to die.

Of the cells affected by retinal degeneration, the photoreceptor cells are most important. Photoreceptor cells are neurons that convert light stimuli into signals for the brain to process.

Neurons are unlike some other cells as they do not divide or multiply. Damaged or dead photoreceptor cells can cause vision impairment and even blindness.

How photoreceptor cells die is still under study. It is believed that the biological pigment in photoreceptor cells of the retina called rhodopsin may have something to do with it. Rhodopsin is extremely sensitive to light, enabling vision in low-light conditions, and is responsible for triggering the eye to see light.

Rise In Diabetes Major Cause In Increase Of Visual Impairment Cases For Young People

Studies show that cases of visual impairment not due to need for glasses is significantly increasing because of the rise in type 2 diabetes.

Obesity is a major contributing factor on the rise of type 2 diabetes among young people. For the past few years, steps have been undertaken to control obesity even going as far as increasing the taxes levied on soda and sugar rich food.

Type 2 diabetes is the most common type of diabetes with 95% of diabetes cases. Obesity, physical inactivity and family history of the disease are the three prime causes of the disease. But with the prevalence of diabetes, also comes its underlying effects and consequences such as vision impairment and a weakened immune system.

Type 2 diabetes is an incurable disease where the body starts to reject its own produced insulin. Insulin is needed to control the glucose (blood sugar) levels in the body. Without insulin, complications such as hyperglycemia can occur.

Bionic Eye, Argus II Retinal Prosthesis System, Gets Approval Recommendation From US FDA

The Argus II retinal prosthesis system is called the bionic eye. It is a retinal implant that is used to send image data straight to the brain. The California company, Second Sight, developed Argus II. Their goal with the Argus II is to provide sight to people who have been blinded from outer retinal degenerations, such as retinitis pigmentosa.

Retinitis Pigmentosa is an eye disease where the retina of the eye is damaged. The retina is locaated at the back of the eye and is responsible for converting light images to nerve signals that the brain can interpret.

The Argus II works by bypassing damaged photoreceptor tissues in the eye. The patient wears special eyeglasses that houses a small video camera, wireless transmitter, and is connected to a small computer worn by the person. The camera captures the image which the computer processes and converts into data that the brain can understand. The wireless transmitter then sends these signals to the eye implant which transmits it directly to the optic nerve, sending the signal directly to the brain.

The eye is implanted with a wireless receiver that receives the data from the glasses and an electrical array that sends it straight to the optic nerve. (See video below).

The optical system is named after the Greek mythological giant, Argus Panoptes. Argus had 100 eyes and was the servant of the goddess, Hera. Argus was considered all-seeing and was relied upon by Hera to stand guard and monitor things.

FDA recommends approval for Second Sight's Argus II retinal prosthesis system in the USA

The U.S. Food and Drug Administration (FDA) Ophthalmic Devices Advisory Panel unanimously voted 19-0 that the probable benefit of the Argus II Retinal Prosthesis System outweighs the risks to health, an important step toward the FDA market approval of this product manufactured by Second Sight Medical Products, Inc. In making this determination, the panel spent ten hours carefully reviewing and discussing data submitted from the international clinical trial of this innovative retinal implant that, for the first time ever, partially restores vision to patients who are blind due to Retinitis Pigmentosa (RP).

Photoswitch Chemical AAQ May Restore Vision To The Blind

Age-related Macular Degeneration (AMD) is an eye disease that affects the macula. The macula is a part of the retina. The retina sends light from the eye to the brain, and the macula allows the person to see the fine detail of the image.

AMD blurs the sharp central vision needed for straight-ahead activities such as reading, sewing, and driving. There are two forms of AMD: dry macular degeneration and wet macular degeneration.

AMD is painless and the progression of AMD is slow that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in both eyes. AMD is a common eye condition among people age 50 and older. It is a leading cause of vision loss in older adults.

Chemical makes blind mice see; compound holds promise for treating humans

A team of University of California, Berkeley, scientists in collaboration with researchers at the University of Munich and University of Washington in Seattle has discovered a chemical that temporarily restores some vision to blind mice, and is working on an improved compound that may someday allow people with degenerative blindness to see again.

The approach could eventually help those with retinitis pigmentosa, a genetic disease that is the most common inherited form of blindness, as well as age-related macular degeneration, the most common cause of acquired blindness in the developed world. In both diseases, the light sensitive cells in the retina — the rods and cones — die, leaving the eye without functional photoreceptors.

The chemical, called AAQ, acts by making the remaining, normally "blind" cells in the retina sensitive to light, said lead researcher Richard Kramer, UC Berkeley professor of molecular and cell biology. AAQ is a photoswitch that binds to protein ion channels on the surface of retinal cells. When switched on by light, AAQ alters the flow of ions through the channels and activates these neurons much the way rods and cones are activated by light.