You may have heard of an ocular disease called keratoconus–a disease in which the outermost clear structure of the eye called the cornea, begins to thin and weaken, resulting in it bulging forward in a cone-shaped fashion.
While keratoconus is not particularly common, it can be a visually debilitating disease.
Fortunately, newer technology is being invented everyday. The most recent treatment for keratoconus is through a procedure called corneal crosslinking.
What is Keratoconus?
Keratoconus is an ocular disease in which a layer of the cornea–called Bowman’s layer–begins to thin and loses its ability to hold the cornea’s shape appropriately. A normal cornea is relatively turgid and holds its spherical shape well.
In keratoconus, over time, the cornea begins to bulge outward creating a cone-like shape rather than being perfectly spherical. It takes several years of progression for a cone to be able to be seen with the naked eye.
Fortunately for keratoconic individuals, technology is ever improving. Optometrists and ophthalmologists can use a special device called a keratometer to map out the shape and thickness of the corneal to detect cones earlier on in the disease and thus initiate treatment before the disease advances too far.
We are not entirely sure what causes Bowman’s layer to weaken in keratoconus, however it is currently thought that excessive rubbing of the eyes, chronic eye allergies, connective tissue diseases (such as Marfan’s syndrome), and genetics all increase the risk of developing the disease.
Keratoconus is typically diagnosed between the ages of 10 and 25 years old–although it can also be diagnosed earlier or later in life as well.
Individuals with keratoconus may not notice changes in the cornea in the early stages as it begins as a painless, slowly progressing disease. However, over time they may note increased problems with glare, high irregular corneal astigmatism, blurry vision, and light sensitivity (photophobia).
As the disease progresses over the years, the layers of the cornea become progressively weaker and flimsier. In some cases, the inner eye fluid (aqueous humor) begins to leak into the cornea and create a blister-like cyst within the cornea called a corneal hydrop.
Like skin blisters, corneal hydrops are rather painful and can pop, causing more pain and swelling within the cornea. This swelling causes hazy vision and can lead to scarring within the cornea, ultimately resulting in permanent vision loss (which can be minor or severe).
In order to prevent the disease from progressing to this painful, severe stage, researchers have developed an out-patient surgery called corneal crosslinking to help strengthen the cornea so that further corneal thinning does not occur.
Corneal Crosslinking to Treat Keratoconus
Corneal crosslinking is a relatively simple process. Currently, a small incisional flap is made out of the anterior corneal (specifically the outermost layer of the corneal, the epithelium) to allow the surgeon better access to the affected area.
Next, a vitamin called Riboflavin (also known as Vitamin B2) is applied to cornea in eye drop form several times to “prep” the cornea. Once the surgeon believes the cornea is at the proper thickness to accept treatment, a UV light is applied to the cornea.
Over the time span of 30 minutes, the surgeon will apply more riboflavin drops alternating with UV light exposure until reaching optimal corneal thickness.
The activated UV light and riboflavin combination creates a stronger modulus to reinforce the cornea. With a stronger cornea, less bulging and cone formation is seen, thus preventing further progression of the disease.
To visualize this, think about a keratoconic eye’s cornea being weakened to have a structural integrity similar to saran-wrap. It can easily be manipulated and does not have very sturdy integrity.The riboflavin-UV treated corneal becomes more similar to thick aluminum foil–still flexible, but much more sturdy and more apt to holding its own shape.
Patients who have undergone corneal crosslinking have been relatively happy with treatment and have reported a decrease in refractive error (decreased glasses prescription), decreased glare, and increase in overall ocular comfort (less itching/irritation).
Corneal crosslinking does not repair the damage that has already occurred in a keratoconus patient’s eyes. However, it can help lessen the symptoms of the disease and slow, if not prevent, the progression of the disease.
Corneal crosslinking is currently a potential treatment option for individuals with progressive keratoconus over the age of 14 years old.
It is important to note that corneal crosslinking is a relatively new treatment. Researchers are currently working on new ways to improve the treatment to make it stronger and more effective for keratoconus patients.
If you or someone you know has keratoconus and is interested in the corneal crosslinking procedure, your eye doctor would be more than happy to discuss the procedure with you to determine if you would make a good candidate.
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