Retinal Degeneration - An overview

Introduction

The retina is a thin layer of tissue that covers the eye's lateral wall. The retina is responsible for capturing images and sending signals to the brain. In addition, the retina contains light-sensitive cells (rods and cones) and nerve cells that receive visual information. The retina sends this information to the brain through the optic nerve, enabling the person to see. Various retinal diseases can affect the vision of a person. Retinal degeneration is retinopathy that causes deterioration in the normal retina. It occurs due to the progressive death of cells of the retina. People who develop retinal degeneration may be affected by their genetic makeup or, in some instances, by an underlying disease acquired during their lifetime.

What Is Pathophysiology Behind Retinal Degeneration?

In inherited cases of retinal degeneration, a person exhibits a genetic disturbance. The affected gene is involved in the biosynthesis and folding of rhodopsin (an eye pigment). Retinal degeneration is due to rhodopsin mutations that affect the function of rhodopsin. In another mechanism of retinal degeneration, overexpression of the rhodopsin gene is seen. In some cases, mutation leads to truncated (short-duration) rhodopsin formation. In addition, it will affect the function of the rod, which will lead to the degeneration of the photoreceptors.

What Are the Causes of Retinal Degeneration?

Retinal degeneration occurs due to the death of retinal cells and tissue. Various retinal diseases or abnormalities can lead to retinal degeneration. These are as follows:

• Glaucoma: It is one of the most typical causes of retinal degeneration. This condition leads to increased intraocular (inside the eye) pressure. In addition, accumulation of aqueous humor occurs in the case of glaucoma, which further leads to a build-up of pressure in the eye. The progression of the condition leads to degeneration of the nerve, ultimately leading to a degeneration of the retina.

• Retinitis Pigmentosa: It is the most common cause of retinal degeneration. It slowly affects the retina and leads to degeneration and, ultimately, vision loss.

• Tear of the Retina: In a retinal tear, a clear and gel-like substance in the eye's center shrinks on the back of the eye (retina) due to sudden force or traction. It leads to symptoms such as floaters and flashing lights.

• Retinal Detachment: It occurs due to fluid under the retina. It causes the lifting of the retina away from the underlying tissue.

• Diabetic Retinopathy: Diabetes retinopathy develops tiny blood vessels (capillaries) in the back of the eye. It leads to deterioration and leakage of fluid under the retina. This causes swelling of the retina and distorts vision.

• Epiretinal Membrane: A delicate scar-like tissue or membrane on top of the retina. It leads to distortion of the vision. As a result, objects start to appear blurred and crooked.

• Macular Hole: A macular hole is a minor defect in the retina's center (macula). The gap may develop from abnormal traction or an eye injury.

• Macular Degeneration: The retina's center begins to deteriorate in macular degeneration. It causes blurred central vision or a blind spot in the visual field in the center.

• Other Causes: Other causes are occlusion of the artery or vein of the retina.

What Are the Risk Factors Associated With Retinal Degeneration?

• Aging: With aging, the process of degeneration fastens, and the capacity to heal the body decreases.

• Smoking: Smoking delays the recovery process and fastens degeneration.

• Obesity: Obesity can also lead to the degeneration of the retina.

• Systemic Diseases: Diabetes or other systemic diseases.

• Eye Conditions: Trauma to the eye leads to various conditions, such as retinal tears or detachment, that can cause retinal degeneration.

• Family History: Patients with a history of retinal diseases are at risk of developing retinal degeneration.

What Are the Symptoms Associated With Retinal Degeneration?

Many retinal diseases, such as retinal degeneration, have some common signs and symptoms. These include:

• Impairment of the vision.

• Blindness in the night.

• Retinal detachment.

• Increased sensitivity to light.

• The appearance of floating specks or cobwebs in the vision.

• Blurred or distortion of vision.

• Progressive loss of vision.

How to Diagnose Retinal Degeneration?

For an accurate diagnosis, an ophthalmologist thoroughly examines the eye and looks for related abnormalities in the eye. The following helps in determining the location of the retinal degeneration and the related disease responsible for it.

• Amsler Grid Test: This test helps check the central vision. The test checks if grid lines appear to be faded or distorted. The doctor will note where the distortion is seen. This test also helps in monitoring the condition and extent of retinal degeneration.

• Optical Coherence Tomography (OCT): This test captures precise retina images and helps diagnose epiretinal membranes, holes in the retina, and swelling.

• Fundus Autofluorescence (FAF): FAF is used to determine the advanced stages or cases. This test reflects the retinal pigment that increases in retinal degeneration.

• Fluorescein Angiography: A dye injected in a patient helps visualize retinal blood vessels better under a special light. This helps identify closed blood vessels and new abnormal vessels that increase retinal degeneration.

• Ultrasound: Ultrasonography helps to view the retina and related structures in the eye. It can also identify degenerative changes in the retina.

• Computed Tomography and Magnetic Resonance Imaging: These imaging methods rarely help evaluate eye injuries or tumors.

What Is the Treatment for Retinal Degeneration?

Unfortunately, there is no proven treatment for retinal degeneration. In this condition, vision loss progresses slowly. The goal of treatment is to stop or slow the disease's course and enhance the quality of life. But in many patients, the damage has already occurred and can not be reversed. Early diagnosis with proper treatment can reduce further loss. Treatment of retinal degeneration is complex and sometimes urgent. Treatment options include:

1. Laser: Laser surgery can treat retinal tears or holes that can cause retinal degeneration. A laser is used to heat tiny holes in the retina.

2. Shrinking of Abnormal Blood Vessels: The doctor uses photocoagulation to shrink abnormal new blood vessels in the eye. It is used in the treatment of diabetic retinopathy.

3. Freezing: To treat a retinal tear, a surgeon applies a freezing probe to the eye's exterior. That can stop further degeneration of the retina.

4. Indenting the Surface of the Eye: A surgery called scleral buckling is used in the treatment of retinal detachment. This technique is used with other treatments.

5. Injecting Medicine Into the Eye: Injecting some medication into the eye is used in treating retinal degeneration, diabetic retinopathy, or broken blood vessels in the eye.

6. Implanting a Retinal Prosthesis: Patients with blindness may need surgery. A tiny electric chip (electrode) is embedded in the retina. A video camera mounted on a pair of eyeglasses provides input to it.

Conclusion

Retinal degeneration causes deterioration in the normal retina. It causes progressive loss of vision. It occurs due to the progressive cell death of the retina. It can be Inherited due to genetics or can be due to some acquired condition. In genetic cases, the mutation in the rhodopsin gene is seen. Therefore, early diagnosis and proper treatment can stop the worsening of the situation. Unfortunately, there is no exact treatment for retinal degeneration.