Dr. Stanley Chang Receives Castle Connolly “Physician of the Year” AwardRead more
Dr. Stephen Trokel elected to The American Society of Cataract and Refractive Surgery Hall of FameRead more
Nurses at Harkness Institute win highest awards from Press Ganey for third year in a row.Read more
The Department of Ophthalmology at Columbia University Medical Center is proud to announce the opening of The Gloria and Louis Flanzer Vision Care Center.Read more
Columbia Ophthalmology Consultants | Comprehensive and Geriatric Ophthalmology | Cornea, Cataract and Refractive Surgery | Retinal | Glaucoma | Pediatric Ophthalmology | Eye Plastic & Reconstructive Surgery | Neuro-ophthalmology
Cornea, Cataract and Refractive Surgery - Anterior Segment
The anterior segment is the front of the eye that includes the cornea, conjunctiva, sclera, iris, ciliary body, and lens. The subspecialty of cornea and external diseases in ophthalmology deals with conditions involving these components of the eye. Such conditions include acute and chronic conjunctivitis, corneal infections and disorders,refractive error such as nearsightedness, farsightedness, and astigmatism, dry eye, keratoconus, and pterygium.
The cornea is the outermost layer of the eye overlying the iris and pupil. It is a transparent layer, much like the clear glass portion of a wristwatch. The cornea is made up of five layers (from outermost to innermost): epithelium (ie. the “skin” of the cornea), Bowman’s layer, stroma, Descemet’s membrane, and endothelium. The cornea’s transparency is due to a variety of reasons: (1) a regularly-arranged pattern of cells; (2) endothelial cells pump water out of the cornea; (3) lack of blood vessels. Due to the lack of blood vessels to the cornea, it receives nutrients from tears and aqueous humor, which is the fluid contained in the area called the anterior chamber, located behind the cornea and in front of the iris.
The cornea and vision
Light enters the eye via the cornea. As the light enters the cornea, it bends or refracts. The light then enters the lens, which is behind the cornea and iris, which refocuses the beams onto the retina, the innermost layer of the eye. Fibers from the retina then transmit the information of light onto the brain. To see clearly, both the cornea and lens must be clear and must focus light precisely to the retina. If the cornea does not refract the light properly, from conditions such as refractive errors or scarring, the retina will receive a blurred image. If the lens becomes cloudy, also known as a cataract, the image will also be blurred.
Many conditions can cause damage to the cornea. Trauma, through a projectile object or lacerations to the eye, may cause an opening of the cornea which would require immediate surgical attention. After repair of a corneal wound, scarring often clouds the cornea. Infections, from bacterial, fungal, or viral etiologies, on the cornea can lead to scarring and even perforations of the cornea. Hereditary conditions, such as keratoconus and corneal dystrophies, can cause irregularity or swelling of the cornea.
Keratoconus is the most common corneal hereditary condition that causes a cone-shaped cornea that requires hard contact lenses and, in some patients, a corneal transplantation.
Fuchs’ endothelial dystrophy is a common hereditary condition in which the endothelial cells of the cornea are inadequate or faulty, causing eventual swelling of the cornea.
The cornea can also become swollen after cataract surgery, particularly in Fuchs’ patients, from damage to the endothelial cells. Often, corneal transplantation allows for replacement of either scarred or swollen corneas. Common indication for corneal transplantation include: corneal infections not responding to medical therapy, visually significant corneal scarring, corneal swelling or edema in long-standing Fuchs’ dystrophy or from prior cataract surgery, keratoconus patients who cannot tolerate contact lenses or have visually significant scarring.
Corneal transplants are one the most successful organ transplantation procedures and have been performed for over 35 years. The procedure involves removing the diseased cornea from the patient and stitching on a new cornea from an organ donor. The procedure is successful in 90% of restoring sight and hope. Several stitches are placed in corneal transplantations, which are removed in a piecemeal fashion, often starting as soon as three months after surgery. These stitches often cause significant astigmatism, which may be lessened with stitch removal or use of hard contact lenses. Often by one year after surgery when the prescription of the eye is stable, glasses or hard contact lenses are prescribed.
Every transplant patient should be aware of the warning signs of infection or graft rejection: increased redness, increased sensitivity to light, decreased vision, and increased pain. Any one of these symptoms warrant attention to the physician and an immediate eye examination.
Sometimes, recipients of corneal transplants have graft failure, either due to graft rejection, infection, scarring, or persistent elevated eye pressure. These patients can receive another corneal transplantation. Often the success rate is less than eyes with successful first transplants, but the success rate is still much higher than other organ transplantation.
New method of corneal transplantation: DSEK, the “sutureless corneal transplant”
DSEK, or Descemet’s Stripping Endothelial Keratoplasty, is a new option for patients requiring corneal transplantation due to cornea swelling. Eyes develop corneal swelling from damage to endothelial cells, the innermost layer of cells that keep the cornea clear. Damage to endothelial cells can happen after any kind of eye surgery or in patients with Fuchs’ dystrophy. Unfortunately, corneal endothelial cells do not regenerate and so these cells cannot be replaced.
In this new procedure, called DSEK, the damaged endothelial cells are removed or “stripped” and a partial corneal transplant, containing healthy endothelial cells from an organ donor, is placed into the eye. An air bubble is injected into the eye to push up the donor graft up onto the posterior surface of the patient’s cornea. There are no stitches needed to attach the partial transplant. The pumping action of the endothelial cells helps create a suction to keep both layers of cornea (graft and patient’s cornea) together
The advantages of DSEK over traditional corneal transplantation include: faster recovery of sight, a stronger eye, less risk of graft rejection, and less risk of stitch-related conditions such as high astigmatism and infections.
Dry eye is a very common cause of ocular discomfort. Healthy eyes have a stable tear film that evenly coats the outer surface of the eye. Symptoms of dry eyes include a gritty or foreign body sensation, increased irritation from fumes or wind, light sensitivity, redness, problems with contact lens use, tearing, eye fatigue, and blurred vision.
Dry eyes can stem from a lack of tear production, an unstable tear film, or rapid tear evaporation. Normally, tear production diminishes with age. The condition is more common in women, especially after menopause. Dry eyes are also associated with certain medical conditions such as rheumatoid arthritis, lupus, scleroderma, Sjogren’s syndrome, thyroid disorders, and diabetes. Healthy tears contain a balanced composition of oil, water, and mucus. Poor tear quality can lead to an unstable tear film and poor coating of the eye’s outer surface. A common cause of an unstable tear film is concurrent blepharitis, or inflammation of the eyelid margin which contains tear glands called meibomian glands. These glands provide the fatty oil, or lipid, component of the tear film. Blepharitis is a common eyelid condition that can usually be addressed with proper lid hygiene and warm compresses. Finally, poor lid function due to eyelid malpositioning or nerve damage can cause prolonged exposure of the eye and subsequent dryness and discomfort. Treatment of dry eyes aims to target the cause of dry eye and restore a more normal tear film. The mainstay of treatment is the use of lubricating artificial tears. Other modes of treatment aim at conserving tears by partially or completely closing tear ducts located on the eyelid margin that normally drain tears. These tear ducts can be plugged with small silicone plugs that are not noticeable. For severe dry eyes, certain topical medications, such topical steroids or topical cyclosporine (Restasis) can be used for under the management of an ophthalmologist. Vitamin supplements such as omega-3-fatty acids and flax seed oil have been found to aid in tear production.
A pterygium is a triangular-shaped, benign growth of tissue on the outer surface of the eye. It may become inflamed and red with growth onto the cornea. The cause is due to sun exposure and dry eyes. As it is a benign condition, conservative therapy involves artificial tear and sunglass use. If the pterygium becomes larger or symptomatic, surgery can be performed to remove the tissue. Primary excision of the pterygium will almost invariably cause recurrence. As a result, healthy tissue from other areas of the patient’s eye, the conjunctiva, can be used to graft onto the area of prior pterygium (called conjunctival autograft). Patients with recurrent pterygium may require excisional surgery with additional therapies aimed at preventing recurrence, ie. use of chemical mitomycin and/or amniotic membrane grafting.