- Bowman’s membrane
- Descemet’s Membrane
Every time we blink, tears are distributed across the cornea to keep the eye moist, help wounds heal, and protect against infection. Tears form in three layers:
- – An outer, oily (lipid) layer that keeps tears from evaporating too quickly and helps tears remain on the eye.
- – A middle (aqueous) layer that nourishes the cornea and the conjunctiva – the mucous membrane that covers the front of the eye and the inside of the eyelids.
- – A bottom (mucin) layer that helps spread the aqueous layer across the eye to ensure that the eye remains wet.
The cornea acts as a barrier against dirt, germs, and other particles that can harm the eye. The cornea shares this protective task with the eyelids and eye sockets, tears, and the sclera (white part of the eye). The cornea also plays a key role in vision by helping focus the light that comes into the eye. The cornea is responsible for 65-75 percent of the eye’s total focusing power.
The cornea and lens of the eye are built to focus light on the retina, which is the light-sensitive tissue at the back of the eye. When light strikes the cornea, it bends—or refracts—the incoming light onto the lens. The lens refocuses that light onto the retina, which starts the translation of light into vision. The retina converts light into electrical impulses that travel through the optic nerve to the brain, which interprets them as images.
The refractive process the eye uses is similar to the way a camera takes a picture. The cornea and lens in the eye act as the camera lens. The retina is like the film (in older cameras), or the image sensor (in digital cameras). If the image is not focused properly, the retina makes a blurry image.
The cornea also serves as a filter that screens out damaging ultraviolet (UV) light from the sun. Without this protection, the lens and the retina would be exposed to injury from UV rays.
After minor injuries or scratches, the cornea usually heals on its own. Deeper injuries can cause corneal scarring, resulting in a haze on the cornea that impairs vision. If you have a deep injury, or a corneal disease or disorder, you could experience:
- Pain in the eye
- Sensitivity to light
- Reduced vision or blurry vision
- Redness or inflammation in the eye
- Headache, nausea, fatigue
If you experience any of these symptoms, seek treatment from An-noor Eye hospital.
The most common allergies that affect the eye are those related to pollen, particularly when the weather is warm and dry. Symptoms in the eye include redness, itching, tearing, burning, stinging, and watery discharge, although usually not severe enough to require medical attention. Antihistamine decongestant eyedrops effectively reduce these symptoms. Rain and cooler weather, which decreases the amount of pollen in the air, can also provide relief.
Keratitis is an inflammation of the cornea. Noninfectious keratitis can be caused by a minor injury, or from wearing contact lenses too long. Infection is the most common cause of keratitis. Infectious keratitis can be caused by bacteria, viruses, fungi or parasites. Often, these infections are also related to contact lens wear, especially improper cleaning of contact lenses or overuse of old contact lenses that should be discarded. Minor corneal infections are usually treated with antibacterial eye drops. If the problem is severe, it may require more intensive antibiotic or antifungal treatment to eliminate the infection, as well as steroid eye drops to reduce inflammation.
Dry eye is a condition in which the eye produces fewer or lower quality tears and is unable to keep its surface lubricated.
The main symptom of dry eye is usually a scratchy feeling or as if something is in your eye. Other symptoms include stinging or burning in the eye, episodes of excess tearing that follow periods of dryness, discharge from the eye, and pain and redness in the eye.Sometimes people with dry eye also feel as if their eyelids are very heavy or their vision is blurred.
The cornea is examined in detail using a slit lamp microscope.
Additional testing may include topography and keratometry (to study the shape of the cornea), pachymetry (to measure the thickness of the cornea), specialized microscopy, assessment of the tear film, and blood tests.
In cases of infections of cornea, small amounts of superficial corneal tissue is removed (Scrapping) and evaluated for presence of type of infection and the organism causing it. This helps in starting the medication specific to the type of infection which promotes early recovery.
Any injury (blunt/sharp object) causing damage to the superficial layers of the cornea leads to corneal abrasion. It is similar to any scratches over the skin of hand due to injury. The patient will have burning of eyes, redness, sensitivity to light, blurred vision and watering. The healing of corneal abrasion generally takes place with 24-48 hours with commencement of appropriate
Corneal tear is caused by a sharp object like wire/blade/iron rod which causes cutting of deeper layers of cornea (like a knife cuts the butter). When the injury is full thickness it can lead to severe damage to the intra-ocular parts of the eye (iris/lens/etc). Any full thickness corneal tear can lead to permanent vision loss.
YES. Any case of corneal ulcer / keratitis / tear needs URGENT treatment. If left untreated or if treatment is delayed, these may lead to permanent damage to cornea and loss of vision.
Corneal Diseases require multi-modality of medications which help in reducing the symptoms and curing the disease. Also these diseases take a very long duration of treatment and frequent follow-ups. The most important factor for early healing and recovery is patient’s compliance to use medications religiously as per the instructions.
As the cornea is a very sensitive tissue, slightest harm can lead to severe reaction leading to loss of transparency of cornea. Thus most cases will have some residual visual loss. Early and mild cases may improve with medications. Long standing and severe cases heal by scarring and may require corneal transplantation.
Pterygium is a pale yellow/pink/red growth of the conjunctiva (layer covering the white of the eye) on to the cornea. It can occur in one or both eyes. When small it doesn’t cause any symptoms. When it is large/thick, I may cause irritation, burning, redness, dryness, watering and decreased vision.There are no known causes of pterygium but generally people who are exposed excessive sunlight (UV light), wind, sand, dust, smoke have more chances to develop pterygium.Pterygium is a degenerative disease and it doesnot regress with medications. The only treatment is surgical removal.At present, the most commonly performed surgical procedure is Pterygium Excision with Autoconjunctival Grafting. With this procedure, there are 90% chances of complete cure. Patients who are predisposed to pterygium, who work long hours in sunlight can have recurrence of pterygium. The recurrence rate with the best surgical treatment is 10%. But if adequate precautions are taken, recurrence rates can be reduced.Using protective sunglasses while going in sunlight is the most important factor which can prevent pterygium formation.
- Medical Management: All cases of corneal ulcers and keratitis (mild to moderate) are first treatment with medications. Medications are meant to reduce the infection load, the inflammation, to improve symptoms and to initiate the corneal healing process. Very aggressive and intensive medical therapy is essential. The patient’s relative has to proper understand the frequency of medications and instill the drops as per the instructions.
Careful scrapping and identification of infectious agent (bacteria/fungi) is done and infection targeted therapy is started. The medications are given for a long duration for complete removal of infection/inflammation. Most cases respond to medical management dramatically. At AN-Noor Eye Hospital, we strive to provide the best quality medications to our patients. Antibiotics are freshly prepared so that they have maximum potency.
- Surgical Options: Advanced and non-healing cases of corneal ulcer/keratitis generally require surgical line of management along with the medications. Also corneal tears do require closure of the tear with sutures.
- Corneal Tear Repair: In case of a corneal tear, adequate and proper corneal suturing is done. The sutures help to maintain the shape and integrity of the eye. These sutures are generally removed after 2-3 months. Visual recovery depends on the extent of the injury and the healing process.
Corneal Transplantation: When the loss of corneal transparency is the cause of visual loss, corneal transplantation is the method of choice of treatment.
- Full Thickness (Penetrating Keratoplasty): When whole thickness of cornea is affected with or damaged due to the corneal disease, a full thickness corneal transplantation is done. The damaged cornea of the patient is completely removed and a healthy cornea from a donor eye is transplanted.cornea
- Deep Anterior Lamellar Keratoplasty: This is performed in those cases in which the anterior/outer cornea is damaged but the inner cornea is healthy. Preserving the inner cornea increases the chances of visual recovery.
- Descemet Stripping / Descemet Membrane Endothelial Keratoplasty: Cases in which inner corneal layer is damaged are treatment with DSEK/DMEK. The anterior healthy cornea is preserved.
- Intalase Enabled Keratoplasty: This is a New Technological Advancement for Full Thickness Corneal Transplantation. Instead of cutting the cornea with scissors, the cornea is cut with Femtosecond Laser, which gives accurate and precise cuts, proper positioning of the donor cornea and excellent post-operative results.cornea2
- Limbal Stem Cell Transplanation: Patients who have poor ocular surface healing(specially cornea) and cases with recurrent pterygium are benefited with Limbal Stem Cell Transplantation.
- Amniotic Membrane Grafting: Patients who have extensive ocular surface damage (cornea and conjunctiva) are now being treated with Amniotic Membrane Transplantation which tends to restore the near normal ocular surface anatomy and physiology.
- Keratoprosthesis: Patients who are blind due to irreversible and extensive damage to ocular surface specially cornea and in whom corneal transplantation will not be successful / cannot be done, are implantation with a Keratoprosthesis. It is a bio-synthetic implant which restores the vision up to a certain extent.
What is keratoconus: It is a degenerative disorder of the eye in which structural changes within the cornea causing it to thin and protrude to assume a conical shape.
Why does it occur: In most of the cases, the cause is unknown. Few cases may be hereditary.
What are the symptoms suggesting it:
- Mild blurring of vision (initial stages)
- Frequent change of glasses
- Sensitivity to light
- Deteriorating vision
- Ocular allergy
- Poor night vision
- Excessive rubbing of eyes.
How to diagnose it:Investigations routinely performed to diagnose it are a complete ophthalmological assessment, refraction, and corneal topography.
What is the treatment of it:
- Intrastromal Rings: Thin semicircular PMMA rings are inserted in the corneal to flatten the conical part of the cornea thus returning it to a more natural shape.
- Corneal Collagen Cross Linking: Riboflavin (Vitamin B2) drops are instilled and activated by Ultraviolet light. This causes strengthening of the corneal tissue and preventing the progression of keratoconus
- DALK: In severe cases, the anterior part of the cornea (which is weak) is removed and a healthy strong cornea of a donor is implanted. Very severe cases require complete corneal transplantation.
- Bosten Scleral Lenses: Special contact lenses are sometimes preferred when surgical intervention is not necessary.
- Customized Contact Lenses: In early cases, customized contact lenses can be worn to help regain the quality of vision affected by keratoconus.