Cornea, External Disease, and Anterior Segment
The cornea is the clear, front part of the eye. It is the first structure that light must pass through to enter the eye and be focused on the retina, allowing clear vision. Because the cornea is responsible for about two thirds of the light focusing power of the eye, a problem with the cornea often leads to problems in vision. Many corneal conditions can be treated with medications, while others may need surgery.
Common Cornea Conditions:
Dry Eye
Dry eye is a very common condition that can affect the cornea. It is estimated that at least 20% of the population suffers from dry eye. Some of the most common symptoms are red, irritated eyes, fluctuations in vision, and foreign body sensation. The causes of dry eye can include multiple factors, including environmental irritants, genetics, age, gender, hormonal changes, and the effects of systemic medications. A variety of treatment options are available for dry eye, but depend on the severity of the symptoms and what is seen on ophthalmic exam.
Corneal Infections
Corneal infections (also called a corneal ulcer or infectious keratitis) can be caused by bacteria, fungi, protozoa or viruses. Corneal infections are often associated with redness, pain, light sensitivity, and reduced vision in the affected eye. Any infection in the cornea can lead to scar formation that often reduces the quality of vision, so prompt diagnosis and treatment is critical. Risk factors for corneal infections include contact lens wear, injury or eye trauma, and skin infections on the fingers or eyelid margin. Most corneal infections are difficult to transmit from one person to another. The most common bacteria causing corneal infections come from the skin and the most common viral corneal infection is caused by herpes simplex I (HSV I) virus.
Conjunctivitis
The conjunctiva is the highly specialized skin that covers the white portion of the eye and lines the inside of the upper and lower eyelid. Inflammation of this tissue is called conjunctivitis or, more commonly, pink eye. The most common cause of conjunctivitis is allergy or hay fever. Allergy typically causes red, swollen, and itchy eyes. Unless the allergy is severe it does not usually affect vision. Viral infections can also cause conjunctivitis leading to red, watery, irritated eyes. Viral conjunctivitis is highly contagious and, if severe enough, can lead to reduced vision. Treatment options are available for both viral and allergic conjunctivitis to help lessen the symptoms and speed recovery.
Fuchs’ Dystrophy
Fuchs’ dystrophy is one of the most commonly inherited dystrophies of the cornea. A corneal dystrophy is a non-inflammatory inherited condition that may be progressive and affect both eyes. In Fuchs’ dystrophy, the internal cell lining of the cornea, called the endothelium, becomes damaged. As the cell damage worsens, fluid can accumulate in the cornea which will slowly reduce vision. Initially patients will notice blurred vision in the morning and glare or halos around lights. As the dystrophy progresses, the vision will be blurred all day long. Fuchs’ dystrophy usually does not manifest until patients are in their 40’s, and is more common in women.
Treatment for Fuchs’ dystrophy begins with hypertonic saline drops to help remove excess fluid from the cornea. If the drops no longer provide relief, surgery in the form of a Descemet’s stripping endothelial keratoplasty (DSEK) can be performed to replace the damaged endothelium. More rarely, a full thickness corneal transplant has to be performed to restore good vision.
Keratoconus
Keratoconus is a common corneal dystrophy that leads to progressive loss of vision, usually in a younger population. A corneal dystrophy is a non-inflammatory inherited condition that may be progressive and affect both eyes. In keratoconus the cornea begins to thin, and as it thins the cornea will begin to change shape from spherical to conical. As the cornea continues to change, the vision will worsen due to increasing regular and/or irregular astigmatism. Many patients start out in glasses or traditional contact lenses and then progress to needing toric (or astigmatism correcting) contact lenses or perhaps rigid gas permeable contact lenses.
Keratoconus tends to affect a younger population. Many people are diagnosed in their late teens and early twenties when they notice their vision changing. The dystrophy tends to progress through about age 40 and then greatly slows down. Treatment for keratoconus starts with contact lens wear, and so long as contact lenses fit and give good vision no surgical intervention is necessary. In some cases, the cornea becomes so misshapen or scarred that a contact lens will not correct the vision. In these cases, implantable corneal ring segments or INTACS can be placed in the eye to try to make the cornea more spherical, leading to improved vision. Approximately 20% of patients with keratoconus seeing a corneal specialist will eventually need a partial or full thickness corneal transplant in order to restore good vision.
There are currently several active areas of research for patients with keratoconus. New treatments such as vitamin B2 and collagen crosslinking will likely be available in the near future.
Cornea Surgery
Full thickness corneal transplant (Penetrating Keratoplasty):
A full thickness corneal transplant can be used to treat a wide variety of corneal conditions. In this procedure, a central, full thickness button of cornea is removed and replaced by donor cornea of similar size. The transplanted tissue is typically sutured into position. The full thickness corneal transplant is an excellent tool to restore vision, but recovery of best vision can take as long as 12 to 18 months.
Intralase Enabled Keratoplasty (IEK)
Intralase Enabled Keratoplasty, or IEK, is very similar to a traditional corneal transplant. The major difference is that with IEK, both the diseased cornea and donor cornea are trephined (or cut) with a laser. Use of the laser allows for greater precision as to transplant size and wound construction. This custom design may allow for faster healing and less post-operative irregularity in the cornea and does allow for greater wound strength. IEK is not for everybody, and only a detailed exam with special imaging studies of the cornea can determine if a patient is a good candidate for a laser guided corneal transplant.
Deep Anterior Lamellar Keratoplasty (DALK)
A deep anterior lamellar keratoplasty or DALK is an advanced technique allowing a partial thickness corneal transplant. In this procedure, the stroma and epithelium are selectively removed leaving the very thin Descemets’ membrane and endothelium intact. Only donor stroma and epithelium are transplanted during this surgery. Visual rehabilitation with a DALK is similar to a full thickness corneal transplant at 12 to 18 months. The major advantage of a DALK is the lower rate of rejection as compared to the full thickness transplant. This procedure is only an option in conditions where the corneal stroma is diseased but the endothelium is healthy, such as keratoconus, lattice dystrophy, and anterior corneal scarring.
Descemets’ Stripping Endothelial Keratoplasty (DSEK)
Descemets’ Stripping Endothelial keratoplasty or DSEK is one of the more recently developed techniques in partial thickness corneal transplantation. DSEK has been a revolutionary treatment for patients with endothelial condtions such as Fuchs’ Dystrophy and pseudophakic bullous keratopathy. In this procedure, a small incision is made in the patient’s cornea and only the endothelium is removed. A thin “slice” of donor cornea consisting of stroma and healthy endothelium is then inserted into the eye and attached with an air bubble. Because of the small incision technique, recovery is greatly accelerated with DSEK. Patients rarely complain of discomfort after DSEK and vision is can be restored as quickly as 2 to 3 months.
Keratoprosthesis (K-Pro)
Keratoprosthesis surgery is for patients with severe corneal disease where multiple traditional corneal transplants have already failed or it is felt that there is no chance for transplant success. In this procedure, a synthetic cornea made of a special polymer is transplanted in place of traditional cornea. This type of corneal transplant can give excellent vision to those previously with no hope of sight. However, medications and antibiotics are necessary for a lifetime.
Anterior Segment Surgery
Implantable Corneal Ring Segments (Intacs): Intacs are small rings that can be implanted in the corneal stroma and are used to reshape the cornea. Intacs have been shown to be beneficial for patients with Keratoconus, both in restoring vision and allowing better contact lens fitting. Intacs are implanted through a tiny partial thickness incision in the cornea, allowing for more rapid recovery.
Anterior Segment Reconstruction
Our surgeons specialize in the repair of eye injury. The injury could be due to trauma or surgically induced damage. This repair includes removal of traumatic cataract, intraocular lens exchange or repair, and repair of iris defects due to injury.
Cataract Surgery
Dr. Raber and Ayres also specialize in cataract surgery in those patients with corneal disease as well as repair of cataract related complications. Implanted lenses for correction of astigmatism and presbyopia correcting lenses are also of particular of particular interest to Dr. Raber and Ayres.