HomeHealth articlesretinitis pigmentosaCan Genetic Changes Lead to Retinitis Pigmentosa?

Role of Mutations of Rhodopsin Receptor Gene in Retinal Degeneration

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A series of eye conditions collectively known as retinitis pigmentosa (RP) can cause blindness. Read more about the topic in detail.

Medically reviewed by

Dr. Shikha Gupta

Published At April 4, 2023
Reviewed AtAugust 22, 2023

Introduction:

Retina is a thin layer of tissue that lies on the back of the eye that transforms light into electrical signals so the brain can perceive the environment. Rods and cones are the two different types of photoreceptor cells found in the retina.The rod cells that surround the outer ring of the retina. Rhodopsin, a type of protein and most prominent cells found in the rod cells which help to mediate dim light vision. The word “rhodopsin" is derived from the Greek word rhódon," which means "rose," . These cells are the first retinal cells to be affected by retinal diseases such as retinitis pigmentosa. Cone cells are commonly seen in the middle of the retina that support the vision of color. Many retinal diseases, including retinitis pigmentosa, are mostly caused by mutations in the rhodopsin gene.

What Is Rhodopsin?

Rhodopsin is a pigment-containing sensory protein that turns light into an electrical signal. It is also known as visual purple. Rhodopsin is present in a wide variety of species from vertebrates to microorganisms. It is found in the retina of the eye and is necessary for vision in low light in many seeing animals, including humans. More specifically, it is found within the densely packed discs that make up the outer segment of the retina's photoreceptor rod cells, which are uniquely adapted for vision in low light.

How Do Mutations in the Light Receptor Rhodopsin Cause Retinal Degenerations Like Retinitis Pigmentosa?

Many retinal diseases, including retinitis pigmentosa, are mostly caused by mutations in the rhodopsin gene. Rhodopsin is structurally categorized as a chromoprotein. A coloured chemical generated from vitamin A called 11-cis-retinaldehyde and the colorless protein opsin make up this protein. The rhodopsin molecule undergoes a fundamental shift in structure when the eye is exposed to light, changing from an 11-cis-retinal component to an all-trans-retinal component. As a result of the configuration change, a phototransduction cascade occurs within the rod, converting light into an electrical signal that is then sent via the optic nerve to the visual cortex in the brain. These cells must cooperate properly in order for vision to function properly. These cells are unable to work normally due to the genetic abnormalities that cause retinal pigmentosa and other inherited retinal disorders.

What Are the Causes of Retinal Disorder?

Changes in specific genes are the root cause of retinitis pigmentosa and other inherited retinal disorders. The retina's cellular structure is regulated by these genes.

What Are the Signs and the Symptoms of Retinal Disorder?

The signs and symptoms of retinal disorder include:

  • Difficulties with night vision.

  • Problems seeing in low light.

  • Experiencing a sparkling or flashing light sensation.

  • Losing the capacity to detect color.

  • Poor vision.

  • Sensitivity to or discomfort with bright light (photophobia).

  • Losing the capacity for color vision.

What Are the Diagnosis of Retinal Disorders?

The diagnosis of retinal disorders includes:

  • Eye Examinations - Eye professionals will do an eye check up by dilating the pupils using special eye drops.

  • Ophthalmoscope - The doctor will place drops in the eyes to enlarge the pupil to see the retina clearly. Doctors will look into the back of the eye with a hand-held instrument.

  • Visual Acuity Test - The eye care professional asks the patient to read letters off a chart (known as a Snellen chart). Initially, the patient reads with one eye covered, followed by the other eye, and finally, both eyes. Next, the doctor can evaluate each eye's distance from 20/20 vision. The findings will provide the patient's eye care provider with information about their vision and any potential prescriptions they may need to rectify.

  • Optical Coherence Tomography - The imaging method known as optical coherence tomography (OCT) employs a low-coherence light to produce two and three-dimensional images with micrometer resolution from an optical scattering medium. Optical coherence tomography scanner provides an automated, segmented representation of the vitreous and macula layers. This image illustrates the degree of vitreomacular traction’s involvement and tension on the macula. This imaging technique is helpful for identifying and treating retinal diseases.

  • Ocular Pressure Eye Test - Ocular pressure eye test, also known as tonometry, is a simple test used by a medical professional to measure the pressure inside the eyes.

  • Electroretinogram - The eye doctor places a gold foil film or a specific contact lens in the eye for an electroretinogram. Then they will measure how the retina reacts to sudden light flashes.

What Are the Treatment Options Available for Retinal Disorder?

Retinal diseases such as retinitis pigmentosa have no known treatment, however, medical researchers are making great efforts to develop new treatments. Several options can prevent further vision loss and perhaps partially restore sight:

  • Acetazolamide - In retinitis pigmentosa, there is a tiny spot in the middle of the retina that may expand. The condition may also affect vision, which is known as macular edema. This medication may help the patient to get better vision and relief from swelling.

  • Vitamin A Palmitate - High doses of vitamin A palmitate may decrease the progression of retinal diseases such as retinitis pigmentosa by a minor amount each year but too many doses may lead to excessive toxicity. Follow the physician's advice and collaborate with them carefully.

  • Retinal Implant - If the retinal disease like retinal pigmentosa is progressed, the patient might be a candidate for a retinal implant that could restore some of the vision. The implant is called Argus II, which is commonly seen in the United States. It is combined with glasses that have a camera and is implanted into one eye. Electrical pulses are changed into images and then transmitted to the retina. About half of the individuals were capable of reading letters that were roughly nine inches high.

  • Sunglasses - Sunglasses shield the eyes from dangerous ultraviolet radiation that could speed up vision loss and reduce the sensitivity of the eyes to light.

  • Others: Other treatment includes the replacement of unhealthy tissues or cells with damaged ones. Healthy genes will be introduced into the retina using gene therapy.

What Precautions Have to Be Taken for Retinal Diseases?

Retinal disorders such as retinitis pigmentosa cannot be prevented because the majority of cases are hereditary. However, there are things it may take to maintain the healthiest possible vision includes:

  • Scheduling and attending the ophthalmologist's appointments regularly.

  • Avoid strong lighting and use sunglasses.

  • Pursuing optimal health by following a nutritious diet and performing a safe exercise.

Conclusion:

Retinal disorders do not progress according to a specific pattern because there are so many distinct genes that can be involved. Different forms develop in people in various ways. Anyone with retinitis pigmentosa should receive appropriate genetic testing and counseling. Attending routine eye exams and according to the provider's advice are the best ways to preserve eye health.

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Dr. Shikha Gupta
Dr. Shikha Gupta

Ophthalmology (Eye Care)

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dna mutationretinitis pigmentosa
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