Introduction:
The cornea is the transparent component of the eye that covers the front region of the eye. It comprises the anterior chamber (fluid-filled region), the iris (colored part of the eyes), and the pupil (black hole at the center of the eye). The primary role of the cornea in the eye is refracting or bending light. It helps to focus the light that enters inside the eye. The cornea is made up of cells and proteins. No blood vessels are present in the cornea as the blood vessels may prevent normal light refraction that affects vision. Since the cornea lacks blood arteries that carry nutrients, it may get its nutrition from tears and the aqueous humor (a watery fluid in the anterior chamber).
What Are the Structures of the Cornea?
Knowledge of the cornea's components aids in understanding potential issues. It consists of four primary layers:
1. Epithelium - Epithelium is the outermost layer of the corneal layer that primarily serves two functions, they are :
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To stop the entry of foreign substances like dust, water, and germs into the eye and other layers of the cornea.
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To create a smooth surface that absorbs oxygen and cell nutrients from tears and disperses them to the rest of the cornea.
2. Bowman’s Layer - A clear tissue layer known as Bowman's layer is situated right beneath the epithelium's basement membrane. Collagen, a layer of strong protein fibers, makes up its structure.
3. Stroma - The stroma lies beneath Bowman's layer, providing around 90 % of the cornea's thickness. It does not have any blood vessels and mostly consists of water (78 %) and collagen (16 %).
4. Endothelium - Endothelium is the innermost and most delicate corneal layer. The clearness of the cornea depends on endothelial cells. Normally, fluid slowly leaks into the middle corneal layers from the eye (stroma). Pumping this extra fluid out of the stroma is the primary role of the endothelium. Improper pumping may cause the stroma to become waterlogged. As a result, the cornea becomes swollen and puffy, leading to blurry and hazy vision.
What Affects Corneal Dysfunctions?
Endothelial cells, which line the inner layer of the cornea, help to maintain the fluid balance within the cornea in a healthy range and protect against corneal swelling in normal conditions. The causes of corneal endothelial dysfunction are improper functioning or cell degeneration may lead to an accumulation of fluid (edema) inside the cornea. These results are blurry vision, and the corneal becomes thickened. Some endothelial dysfunctions cases like Fuchs dystrophy are inherited.
What Are the Risk Factors of Corneal Dysfunctions?
The causes of corneal epithelial dysfunction include:
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Genetics.
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Age.
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Surgery.
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Inflammation.
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Systemic conditions.
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Drugs
What Are the Medical Conditions That Affect Corneal Endothelium?
The common problem that affects corneal endothelium is
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Fuchs Dystrophy - This is an inherited condition where the improper functioning of endothelial cells may cause blurry vision. Commonly seen in the middle of the 40's and 50's.
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Lattice Dystrophy - Abnormal buildup of protein fibers in the stroma. This condition is commonly seen in childhood.
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Map Dot Fingerprint Dystrophy - A condition that affects the basal layer of epithelium, which separates it from the stroma. It results in a layer of the cornea developing folds resembling dot patterns, little fingerprints, or continents on a map.
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Bullous Keratopathy - Bullous keratopathy is an eye condition where a tiny blister appears in the cornea due to dehydration.
What Are the Signs and Symptoms of Corneal Dysfunctions?
The signs and symptoms of corneal endothelial dysfunction are
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Blurry and cloudy vision.
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Swollen eyes.
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The appearance of tiny blisters.
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Redness.
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Seeing halos around light.
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Extremely sensitive to light.
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Itchy eyes.
How to Diagnose Corneal Dysfunctions?
The common diagnostic option available for corneal diseases are:
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Physical Examinations - Eye professionals will do an eye check by dilating the pupils using special eye drops.
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Pachymetry - This test helps determine the thickness of the corneal layer of the eye.
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Slit Lamp Test - The slit lamp test is a non-invasive test to check the entire eye. This test is performed when the patient is seated in the examination chair and also instructed to rest their chin on the chin rest and their forehead against the forehead band. This maintains the patient's head steady during the exam. This test may help the doctor to determine abnormal bumps (guttae) on the inner surface of the cornea and swelling.
What Are Treatment Methods Available for Corneal Dysfunctions?
The treatment method for corneal endothelial diseases are
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Eye Drops or Ointments- The doctor may advise certain corticosteroid eye drops and ointments for mild to moderate corneal endothelial diseases. These medications may relieve the cornea from dehydration, swelling, and itching.
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Eyeglasses - The doctor may advise special coating eyeglasses may help to reduce corneal swelling.
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Corneal transplant - Corneal transplant may advise if the disease is severe. A corneal transplant is a procedure that removes a diseased cornea and replaces it with a healthy cornea. It can be performed by different techniques like penetrating keratoplasty, lamellar keratoplasty, etc. Depending on the condition of the disease, the doctor may decide which method to use. In this procedure, the doctor will perform a physical examination of the patient, carry out certain lab tests, and the patient has to sign an informed consent form, and the surgery date and time will be scheduled. The procedure is performed under general anesthesia or local anesthesia and a sedative; they are:
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Draping the face area around the eye.
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To keep the eyelids open, a speculum is put on them.
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Some lubricant is used to prevent the eye from drying.
What Are Complications of Corneal Endothelial Surgeries?
Surgeries like corneal transplantation are a surgical process; hence, it is still regarded as the safest procedure. Rejection occurs in roughly one out of every ten transplants when the body's immune system assaults the donor tissue. Most of the time, eye drops can be used to reverse it. Common complications of corneal endothelial surgeries include:
Conclusion:
If someone wears contact lenses, adhere to strict hygiene guidelines. The major cause of developing corneal disorders is improper use. As a result, there will be lower possibilities of corneal infections related to their use. Avoid wearing contacts while sleeping. This practice significantly increases the risk of cornea infections. Inherited diseases from the parents cannot be prevented (like dystrophies). However, if anyone identifies and addresses them quickly, they may be able to preserve their eyesight.
