Keratoconus is an eye condition that thins the cornea (the front clear part of the eye) and causes it to lose the normal curved shape, making a cone-like shape. The cornea is responsible for focusing most of the light that enters the eye. When the cornea is distorted from keratoconus, the vision suffers. It would be like looking through a circus mirror. Glasses are not able to fully correct the vision in keratoconus because of the irregular shape. External factors, such as constant or vigorous eye rubbing, can contribute to this disorder. There is likely a genetic predisposition for keratoconus, with symptoms appearing as early as the teens and early twenties. Dr. Waite is an expert in keratoconus and is dedicated to the most recent treatments, such as corneal cross-linking and topography-guided PRK. If you have keratoconus, request an appointment with Dr. Waite so you can fully understand the best options for your vision.
What causes keratoconus?
The causes of keratoconus are multifactorial. Genetics makes a person predisposed to keratoconus, but the disorder may not manifest until certain conditions are met. The main environmental factor that causes keratoconus is eye rubbing. Your mother was right when she told you not to rub your eyes. The pressure on the eye caused by excessive and forceful rubbing can weaken the structure of the cornea and cause it to lose its perfect shape. Other factors that can lead to keratoconus are all related to eye rubbing. Chronis allergies, hay fever allergy, and eczema, are risk factors that may contribute to the development of keratoconus because they lead to eye rubbing. A higher rate of keratoconus is found in conditions such as Down syndrome, sleep apnea, floppy eyelid syndrome, Leber congenital amaurosis, Ehlers-Danlos syndrome, Marfan syndrome, and osteogenesis imperfect.
More FAQ’s about Keratoconus
What are the signs and symptoms of keratoconus?
The first symptom noticed in keratoconus is often blurred vision. The glasses prescription will usually shift, and astigmatism will often increase resulting in blurry or distorted vision. This occurs because the shape of the cornea is slowly changing and losing its normal curvature. This usually happens in both eyes but can be worse in one eye compared to the other. Keratoconus can cause symptoms that range from mild blurry vision to severe vision loss. Typically, symptoms become noticeable in adolescence or early adulthood, usually during the teens through early 20’s. Keratoconus will commonly progress during the second and third decade of life. Over time, the progression of keratoconus will slow. Usually by the time a patient with keratoconus is in their 40’s or 50’s the progression will stop.
The cornea focuses about 70% of the light coming into the eye. The lens focuses the remaining 30% of the light so that when the light reaches the retina, it is well focused and clear. Light is transformed by the retina into nerve signals which are sent to the brain through the optic nerve. The brain then interprets the data coming from the retina and allow us to see. The cornea plays a very important role in this process. If the cornea loses its perfectly curved shaped from keratoconus, then the vision will be blurry even if the lens and retina are completely normal.
How is keratoconus diagnosed?
New technologies and understanding have significantly improved our ability to diagnose keratoconus. The most common test is corneal topography. This is a map of the curvature of the cornea with colors to show the shape of the front surface of the cornea. Corneal tomography can map the posterior cornea showing early keratoconus changes. A new adjunct to corneal topography and corneal tomography is corneal epithelial mapping. The first layer of the cornea called the epithelium manifests signs of keratoconus with thinning over the protruding cone. These three methods can diagnose even the earliest and most subtle cases of keratoconus. It is now possible to diagnose keratoconus before there are any symptoms noticed by the patient.
How is keratoconus treated?
Corneal crosslinking is the standard of care for keratoconus. It is the only method shown to halt the progression of keratoconus. In corneal crosslinking, riboflavin (Vitamin B2) eye drops are placed on the cornea and allowed to soak in. This usually takes about 30 minutes of drop application. After the riboflavin has saturated the cornea, UV light of 385nm wavelength is shined on the cornea for a total energy of 5.4J/cm2. This creates new covalent bonds between the different structures in the collagen matrix of the cornea. The new bonds strengthen the cornea and stop the progression of the keratoconus. The irregular shape will not change back to normal after crosslinking, but many patients do notice an improvement in the vision. The process takes about one hour per eye. It is similar to a sunburn on your cornea, so the post-operative recovery is uncomfortable with temporary burning. The FDA approved protocol for corneal crosslinking requires removal of the corneal epithelium to allow the riboflavin to absorb into the cornea. This is referred to as “epi-off” crosslinking. With improved techniques and technology, corneal crosslinking is now possible without removing the epithelium which is called “epi-on” crosslinking. Epi-on crosslinking is safer with a faster recovering and much lower risk for infection and scarring. The efficacy of epi-on crosslinking has been shown to be as good as epi-off crosslinking in multiple studies. The crosslinking we perform at Waite Vision is epi-on corneal crosslinking. Since it is so safe, we perform crosslinking on both eyes on the same day to allow for a quicker recovery.
After corneal crosslinking, patients will still need glasses or contact lenses for best vision. Some patients are good candidates for surgical vision correction after crosslinking. After the cornea is stronger from corneal crosslinking, topography-guided PRK can correct the vision so glasses and contact lenses are no longer needed. PRK is an innovative treatment that can be used for keratoconus since crosslinking makes the cornea strong enough for vision correction. As experts in keratoconus, Waite Vision is proud to offer this procedure to bring hope to our patients. Similar to LASIK, PRK (photorefractive keratectomy) is used to treat nearsightedness, farsightedness, and astigmatism in affected individuals. Topography-guided PRK, which incorporates your unique corneal topography map into the laser procedure can result in better vision than possible before. It reshapes your corneal surface using your unique corneal topography data to enhance your corneal optics and visual performance.
In the most severe cases of advanced keratoconus where glasses and contact lenses no longer work, corneal transplantation may be the best method for visual rehabilitation. During a cornea transplant, the misshapen layer of the cornea is removed and replaced with a clear cornea from an organ donor who has passed away. For keratoconus the best method for transplantation is a partial corneal transplant (deep anterior lamellar keratoplasty DALK) where only the front 85% of the cornea is replaced. This results in a lower rejection rate of the new cornea. Fortunately, most patients with keratoconus do not progress to the point where a corneal transplant is needed.
Dr. Waite can help you choose which of these therapies will be beneficial for you after a thorough eye examination with all of our state of the art testing. Waite Vision is dedicated to continuing education to bring information about the most recent developments in keratoconus therapies to our patients. Call our office today to request an appointment to learn more about all our ophthalmology team offers our patients.