There are a number of types of corneal dystrophy with some being quite rare and others being somewhat frequently seen and diagnosed by the eye doctors at D’Ambrosio Eye Care. We provide consultation and diagnosis for corneal dystrophies such as Fuchs’ Dystrophy, Map-Dot-Fingerprint Dystrophy, Lattice Dystrophy and Keratoconus, and, where indicated, can help patients with treatment options and recommendations to help preserve their vision.
Fuchs’ Dystrophy is a slowly progressive disease of the cornea that can develop in both eyes and is slightly more common in women than men. While it is possible to observe Fuchs’ Dystrophy in people in their 30’s and 40’s, it usually does not compromise vision until people are in their 50’s or 60’s. The innermost layer of cells in the cornea, called the endothelium, is a single layer of non-regenerating cells. The endothelial cells are responsible for pumping water out of the cornea and helping to maintain corneal transparency. While the reason is poorly understood, in Fuchs’ Dystrophy, endothelial cells die, causing the remaining endothelium to shoulder the burden of pumping water, with reduced efficiency. This results in corneal swelling and distorting vision. In its later phases, Fuchs’ Dystrophy is often associated with considerable pain as the epithelium “blisters” by forming “bullae”, which begin to burst.
Early in the course of Fuchs’ Dystrophy patients will wake up with blurry vision that gets progressively clearer as the day passes. This phenomenon occurs because the cornea normally takes on water and swells during sleep. A healthy endothelial pump is necessary in order to restore the cornea to a normal thickness. In Fuchs’ Dystrophy, the endothelium removes fluid from the cornea less efficiently. As the Fuchs’ Dystrophy disease worsens and the vision begins not to clear, we will attempt to help reduce the corneal swelling each day with eye drops and ointments. However, when these measures fail to provide comfort and clear vision, it may be necessary to have some type of corneal transplant. One of the more popular treatment options is a type of transplant procedure called DSEK (Descemet’s Stripping Endothelial Keratoplasty) where it is possible to transplant endothelial cells, which may help certain Fuchs’ Dystrophy patients overcome their discomfort and vision problem.
The outermost layer of the cornea, called the epithelium, is attached or anchored to an underlying basement membrane, called Bowman’s Membrane, in order to remain healthy. Sometimes the epithelial basement membrane develops abnormally making it difficult or impossible for the epithelium to adhere properly to the basement membrane. If the epithelium does not adhere properly, Recurrent Corneal Erosions will occur. Recurrent Corneal Erosions are painful and cause the corneal surface to become irregular resulting in intermittent blurry vision along with the discomfort and foreign body sensation. Map-Dot-Fingerprint Dystrophy is also known as Epithelial Basement Membrane Dystrophy because it is caused by a lack of the healthy formation of the Basement Membrane. It affects adults between the ages of 40-70 and can sometimes begin earlier. As the name implies, its appearance is of a map of gray areas, which may also be accompanied by opaque dots, and fingerprint-like whirls or lines.
We often detect Map-Dot-Fingerprint Dystrophy during a routine eye examination in patients who are asymptomatic. If treatment is required to control the pain for those patients who are symptomatic, we may prescribe lubricating eye drops, patch the eye, apply a soft bandage contact lens, oral medication, or in more severe cases, scrape the cornea to attempt to achieve better adhesion of the epithelium. In some cases, we might suggest that the best results can be achieved using Excimer Laser Phototherapeutic Keratectomy (PTK) to smooth the surface of the cornea.
Lattice Dystrophy occurs as a result of the accumulation of abnormal protein fibers, or amyloid deposits, in the middle cornea layer called the corneal stroma. If these deposits become dense enough they will become opaque and affect the corneal transparency so that vision is reduced. If these deposits occur under the outermost layer, the epithelium, they can cause recurrent erosions of the cornea, which can be painful and disturb the normal corneal curvature, effecting vision.
In instances where there are recurrent corneal erosions and pain, it might be necessary to prescribe eye drops, ointments and occasionally an eye patch or bandage soft contact lens. Early Lattice Dystrophy seems to respond well to Excimer Laser Phototherapeutic Keratectomy (PTK) whereas more serious cases may require a corneal transplant.
Keratoconus is a corneal problem that results in progressive thinning and instability of the tissue so that the cornea begins to bulge outward and become cone like.
As the cornea begins to bulge, it causes changes in the refractive power of the eye producing nearsightedness and astigmatism. Keratoconus usually affects both eyes. At first it may be possible to correct your vision with contact lenses. Unfortunately, for about 20% of patients, contact lens intolerance develops making corneal cross linking or a corneal transplant necessary.
Management & Treatment of Keratoconus
Eyeglasses & Contact Lenses-Eyeglasses and soft contact lenses may be well tolerated and provide satisfactory comfort and vision when Keratoconus is mild. Most often, the quality of vision tends to decline so that patients require Rigid Gas Permeable Lenses (RGP) for vision correction. Other contact lens options for Keratoconus include hybrid contact lenses that combine the superior vision benefits of an RGP lens with the comfort benefits of a soft lens and even very large gas permeable contact lenses that fit over the sclera or white of the eye, called “scleral lenses”. With comprehensive contact lens care generally only 10-20% of patients’ progress to the point of needing medical or surgical intervention.
Corneal Cross Linking-Corneal Cross Linking is a non-invasive treatment that has been proven to strengthen the weak corneal structure in Keratoconus. This treatment method works by increasing collagen cross-linking, which serve as the natural “anchors” within the cornea. These anchors are responsible for preventing the cornea from bulging and becoming steep and irregular and thus causing Keratoconus. Corneal Cross Linking is administered by placing riboflavin eye drops onto the surface of the eye and exposing the surface to a precise amount of ultraviolet light. Corneal Cross Linking offers a possible solution for many Keratoconus patients who have progressed to a significant amount of visual disturbance but not so much so as to require a cornea transplant.
Corneal Transplantation-When Keratoconus has progressed to the point that contact lenses are no longer well tolerated and Corneal Collagen Cross Linking cannot provide good vision correction, a cornea transplant is the best choice. In most cases of Keratoconus a Penetrating Keratoplasty (PK) is the preferred surgical solution although sometimes the Cornea Surgeon may recommend a Lamellar Keratoplasty (LKP). With PK the cornea surgeon removes the central portion of the damaged cornea with a “cookie cutter” like instrument called a trephine and replaces it with a clear cornea obtained from the eye bank. The donor cornea is very carefully sewn into place using sutures that are thinner than a human hair. When the new cornea has healed properly, the fine sutures or stitches can be removed right in the office in most cases. PK is the most common type of cornea transplant as it has the potential to provide the clearest vision after healing because there is no interface (layer) to look through. However, the healing time is somewhat long and the use of a contact lens might be required for the clearest vision. Sometimes Lamellar Keratoplasty (LKP) may be used if the damaged corneal tissue is mainly located in the outermost 50% of the cornea. In LKP the outermost half of the cornea is carefully dissected and removed along with any damaged tissue. Then a new donor cornea is gently sewn into place. This type of corneal transplant is less invasive and will allow your eye to be stronger after surgery than it would be with a regular full thickness transplant, or Penetrating Keratoplasty. However, in some cases there can be some loss of clarity from the interface between the new and remaining layers of the cornea.
If you require corneal cross linking or a corneal transplant we will take all the time necessary to explain the risks, benefits and likelihood of success in your particular situation. Please be assured that all of your questions will be answered so that you can make an educated and informed decision about your treatment options at D’Ambrosio Eye Care.