What Is Retina?
The retina is located on the opposite side of the lens and pupil. It is made of two parts: the peripheral retina and the macula. The macula is responsible for central vision as it is located at the center of the retina. The peripheral retina is, as the name suggests, responsible for peripheral vision or the surrounding of the object. There are many types of cells that the retina contains. For instance, photoreceptors such as rods and cones. The retina is a thin layer at the back of the eyeball, which is part of the eye that interlinks the light that enters the eye and the image or object one sees.
The light that enters gets converted by the retina and sent to the brain as an electric signal. The photoreceptors, the cells in the retina, are responsible for converting light energy to an electrical signal that travels through the optic nerve and reaches the brain. Photoreceptors such as rods are responsible for dim light, and cones are responsible for the color of the vision. Ultimately these key parts of the mechanism are responsible for the images that the eyes can see.
What Is the Relation Between Oxidative Stress and the Eyes?
Commonly, oxidative stress is an imbalance between the body’s production and the accumulation of oxygen. In other words, it is the imbalance between the antioxidant and pro-oxidant systems which generates the by-product, such as reactive oxygen species (ROS). During aerobic metabolism in the cells, the continuous detoxification caused by oxidants can lead to oxidative stress. The conditions such as age-related macular degeneration or cataracts are caused by this system imbalance. Polyunsaturated fatty acids make the lens and other structures of the eyes more susceptible to oxidative stress damage.
Which Ocular Diseases Cause Oxidative Stress in the Eyes?
The following are the ocular diseases that suggest oxidative stress in their conditions:
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Dry Eye Disease: The accumulation of reactive oxygen species on the ocular surface leads to oxidative damage, which is the causing factor of dry eye disease.
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Glaucoma: It is caused by damage to the optic nerve. The oxidative stress can damage the trabecular meshwork, which further leads to the alteration of aqueous outflow. This leads to an intraocular pressure increase, which is the major sign of glaucoma.
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Age-Related Macular Degeneration: It is a condition caused by oxidative damage to the bruchs complex. This leads to the damage of retinal pigment epithelium, Bruch’s membrane, and choriocapillaris.
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Retinitis Pigmentosa: It is a disorder caused by a family history of the condition, where the degeneration of photoreceptors such as cones and rods is seen. Oxidative stress causes damage which leads to defective antioxidant mechanisms. This is responsible for retinitis pigmentosa.
What Is Retinal Degeneration?
Retinal degeneration is a neurological disorder caused by either environmental or pathological damage to the retina. It is an incurable condition that causes many eye-related complications such as cataracts, retinal pigmentosa, age-related macular degeneration, etcetera. This disorder is the major cause of blindness and visual impairment. There is no cure for this condition yet.
What Is Retinitis Pigmentosa?
Retinitis pigmentosa is a bundle of disorders that causes many complications related to the light-sensitive layer of the tissue at the back of the eye. Retinal pigmentosa is caused due to genetic history of the family, where the patient eventually ends up losing his vision completely. At a young age, patients with retinal pigmentosa have trouble adjusting their sight to dim light. Moreover, the symptoms of this condition include loss of peripheral vision, bright light sensitivity, and loss of color vision. There is no cure for this condition. However, supportive therapy and rehabilitation training can help with the symptoms.
What Is Age-Related Macular Degeneration?
The macula is the part of the eye that is responsible for central vision. Age-related macular degeneration (AMD) is the condition that affects this part and causes blurring of central vision, no matter the distance. Although age-related macular degeneration does not cause complete blindness, however, due to its effect on central vision, the person might feel difficulty in the overall vision. There are two types of AMD, dry AMD, and wet AMD. Dry AMD is caused by the thinning of the macula with age. Wet AMD is caused by abnormal blood vessel growth affecting the macula. People with Age-related macular degeneration often have symptoms such as trouble seeing with dim light and blurred vision. The treatment of AMD depends upon the severity of the condition.
What Is the Interlink Between Oxidative Stress and Retinal Degeneration?
Age-related retinal degeneration causes a significant increase in oxidative stress. Oxidative stress is the accumulation of damaged macromolecules. The needless amount of reactive oxygen species is the reason behind morphological and functional damage related to retinal ganglion cells, retinal pigment epithelium, and endothelial cells. Moreover, factors such as inflammation, endoplasmic reticulum stress, light exposure, and age-related degradation are the reasons behind increased oxidative stress.
How Does Retina Protect Against Oxidative Stress?
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Carotenoid lutein is a substance found on ocular tissues such as the retina, which play an essential role in slowing down the retinal degeneration process. It acts by absorbing blue light and its antioxidant property. The study shows that lutein reduces the level of photosensitizers and dioxygen molecules by reacting with a free unpaired electron. This hinders the peroxidation process of phospholipids in the membrane. This prevents the oxidation of the cells.
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Moreover, the other property of lutein is to absorb blue light. There are some studies that show that lutein has a property that can reduce the intensity of blue light by 40 to 90%. As the lutein can absorb short-waved blue light before it is processed, the oxidative damage to the retina can be further decreased by reducing the photochemical damage. This can also reduce the chances of age-related macular damage and increases visual acuity.
Conclusion
The retina is a very delicate and important part of the eye structure. There are many refractive errors and disorders that affect the retina. Oxidative stress related to these conditions can make the severity more complicated. For the management of these conditions, the key is regularly checking up at the first appearance of the symptom. However, some conditions have no cure, but regular checkups and supportive therapy can surely be helpful.
