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keratoconus


+ signs and symptoms
+ common causes
+ treatment methods
 
Keratoconus is an eye disease that is highly progressive. The cornea, which is typically round, starts to thin out and become bulging until it reaches a cone like shape. This shape serves as a deflector to light as it comes into the eye and goes toward the retina. This causes visual distortions. Keratoconus can be present in one or both of the eyes. It will often start in the late teenage years or early twenties.
 

signs and symptoms

While the cornea takes on a more irregular shape, progressive myopia and astigmatism begins to develop. This creates issues with blurry and distorted vision. Light sensitivity and glare may also be present. Often times, patients that are keratoconic will experience significant changes in eyeglass prescriptions each time they see their eye care practitioner.
 

common causes

It has been suggested by recent research that weakening corneal tissues lead to keratoconus. This may be related to an enzyme imbalance in the cornea, which puts the cornea at a higher susceptibility to oxidative damage that comes from free radical compounds. This in turn causes a weakening and a forward bulge of the cornea. The risk of this happening is theorized to be genetic predisposition. This would explain why more than one person in a family is affected by keratoconus. This condition is also connected with too much exposure to the sun's ultraviolet rays, a history of ill fitted contact lenses, chronic irritation of the eyes and rubbing of the eyes.
 
 
keratoconus contacts

 

treatment methods

For those who have the mildest form of keratoconus, soft contact lenses and eyeglasses may be of some help. However, as the condition continues to progress and the thinning of the cornea gets worse, making the shape even more irregular, glasses and lenses will no longer give you proper visual correction. Treatments for all ranges of keratoconus include:
 
Custom Soft Contact Lenses: Contact lens makers have recently put out custom soft contact lenses that are designed especially for those who need mild or moderate keratoconus correction. They are produced on a made to order type basis and done with fine detailed measurements of the user's keratoconic eyes. They might be even more comfortable than hybrid or gas permeable lenses for some people.
 
Recent research studies of visual performances dealing with soft toric lenses and gas permeable rigid lenses for mild keratoconus correction show better acuity in situations that are low contrast. The soft toric lenses were equally suited in acuity for high contrast tests.
 
For those with keratoconus that wear contacts part time because wearing GP lenses full time is not bearable, custom soft toric lenses are a viable option. These custom contacts are more expensive than regular soft lenses, but some insurance may cover part of the costs that are associated with keratoconus lenses and treatment.
 
Gas Permeable Contact Lenses: If soft lenses or eyeglasses are not controlling keratoconus successfully, perhaps gas permeable contacts are preferred. The rigid material used to make the lenses allows them to go over and above the cornea, thus replacing the irregular shape with a surface that is smooth and uniform in order to improve upon your vision. Keep in mind though that soft lenses tend to be more comfortable than GP lenses. Also keep in mind that it is time consuming and challenging to be fit for keratoconic lenses. Expect to see your eye doctor frequently so everything can be fine-tuned, especially if the condition is growing worse even with the lenses.
 
Piggybacking Contact Lenses: Since fitting GP lenses over a cornea that is cone shaped can be an uncomfortable experience for those with keratoconus, some eye doctors decide to piggyback two separate kinds of contacts for the same eye.
 
When it comes to those with keratoconus, this involves putting a soft lens over the eye and fitting a GP lens over it. This method ups the comfort level for the wearer sine the soft lens acts like a cushion under the harder, more rigid GP contact.
 
Your eye doctor will closely monitor the piggyback fitting to ensure that your eyes are getting enough oxygen. Not getting the proper amount of oxygen to the eyes surface can be a problem when wearing two lenses at once. But, most current contact designs usually have enough H20 permeability for a safe piggyback fit.
 
ClearKone Hybrid Contact Lenses: This type of hybrid contact is made by SynergEyes. It combines a rigid centre that is extremely oxygen permeable with a soft skirt that is peripheral. This lens was developed just for those with keratoconus. The chief GP area of the contact lens jumps over the cone shaped cornea which give an increase in comfort.
 
Hybrid contact lenses come in a large variety of parameters in order to give a fit that conforms almost perfectly to the keratoconic eyes irregular shape.
 
Scleral and Semi Scleral Lenses: These lenses are gas permeable and large in diameter. In fact, they are large enough to allow the edge and the periphery to comfortably sit on the white of the eye. Scleral lenses serve the purpose of covering a bigger area of the sclera, while the semi scleral lens covers a smaller zone.
 
Since the centre of both the semi and full lens goes over the irregular shape of the cornea, they do not put on any pressure to the surface. This makes for a more comfortable fit. There is more stability in the larger lenses as compared to traditional GP lenses, which shift each time you blink since they only cover one portion of your cornea.
 
Intacs: Intacs are corneal inserts that are applied surgically. They are made by Addition Technology and got their FDA approval in August 2004 for treating those with keratoconus. The small plastic inserts a put right under the surface of the eye in the corneas periphery. They help in the reshaping of the cornea so you have clearer vision. People who cannot function visually through the use of contacts or glasses may need to get the Intacs.
 
There have been a numerous amount of studies that have shown Intacs are good for improving the best spectacle corrected visual acuity, or BSCVA, of those with keratoconic eyes on the average of about two lines on standard eye charts. These implants have the advantageous benefit of being exchangeable and removable, and the procedure takes just about ten minutes. Intacs may delay corneal transplants but they cannot prevent them from occurring at some point if there is continued progression of the keratoconus.
 
Corneal Crosslinking: Corneal crosslinking, also known as CXL, works by strengthening the tissue of the cornea so that the bulging of the surface halts in its tracks. There are two separate theories of corneal crosslinking; epithelium off and epithelium on.
 
The epithelium on method, also known as trasnepithelial crosslinking, leaves the surface of the cornea intact. This method requires extra time for penetration of the riboflavin into your cornea. The advantages include less discomfort, faster recovery and less risk of developing an infection. In 2008, research done at the University of Siena in Italy showed results that were positive in all 22 sets of eyes that were tracked for three years after this type of CXL treatment. Doctor Brian Wachler began developing and preforming this type of crosslinking back in 2003. He has reported that the results in keratoconus patients were excellent. One patient, an Olympic bobsledder by the name of Steve Holcomb, had experienced such an improvement that he won Gold in 2010.
 
In Australia corneal crosslinking is still in trial stages and if proved successful enough will be made widely available in the future.
 
The need for transplants in keratoconus patients may be reduced significantly by corneal crosslinking. This procedure is also being examined as a method of preventing and treating LASIK complications.
 
Topography Guided Conductive Keratoplasty: Though further study is necessary, the earliest results in from a small study that involved topography guided conductive Keratoplasty, also known as CK, showed that the procedure may help in smoothing out corneal surface irregularities. The treatment applies energy from radio waves that are used with a probe at many points in the periphery of your cornea in order to reshape the eyes surface. A computer creates a topographic image map from the surface of the eye to individualize plans of treatment.
 
Corneal Transplant: There are some people who have keratoconus that cannot stand using rigid contacts. Some people have simply gotten to a point where lenses and other treatments are no longer helping. This is when a corneal transplant becomes necessary. This method is also known as penetrating Keratoplasty. Even once a transplant is done, it is still likely that you will need to wear contacts or glasses for a clearer level of vision.