The cornea, the front window of the eye that also participates in focusing light, is normally shaped like a sphere or a dome. In patients with keratoconus, the cornea slowly changes shape into a more cone-like shaped due to weakness of the collagen. Generally, keratoconus patients can see well for long periods of time with hard contact lenses or hybrid lenses (with a hard center and a soft skirt). However, keratoconus over time can compromise vision even with contacts or can cause scarring or pain. Keratoconus does tend to run in families and is worsened by eye-rubbing. It is important to minimize eye-rubbing, and drops can help with that.
When contacts or glasses no longer work or if there is progression of the keratoconus, options to strengthen the cornea include Intacs (which are plastic segments placed inside the cornea for mechanical support) and cross-linking (using a laser and Vitamin B2 eyedrops to strengthen the collagen fibers within the cornea). Intacs is approved in the US and typically covered by insurance. Crosslinking is still in clinical trials in the US and not yet FDA-approved. Corneal transplants (both partial and full-thickness) are also an option for advanced keratoconus available at the Eugene practice of Dr. Ambati.
Intacs
Intacs are plastic ring segments placed within the deep substance of the cornea to help provide mechanical support and improve the contour, or shape of the cornea. Similar to an underwire, they can help change the shape of the cornea from a cone shape in patient with keratoconus to a more normal, spherical shape. This helps reduce nearsightedness and astigmatism. However, Intacs do not stop progression of keratoconus completely. But Intacs generally improves visual resolution and quality, and help patients be able to successfully wear a soft contact lens or glasses successfully.
Crosslinking
To stop progression of keratoconus and minimize the risk that a patient will go on to need a cornea transplant in the future, ophthalmologists use a technique called collagen crosslinking to strengthen the substance of the cornea. This involves placing eyedrops of riboflavin (Vitamin B2) solution on the cornea followed by light from a ultraviolet lamp. Ask your physician about the different techniques that are available in different parts of the world – epithelial off vs. epithelium on, conventional vs. accelerated. Crosslinking generally does reduce nearsightedness and astigmatism to a mild degree. Depending on your eyes, you may benefit from a combination procedure with Intacs. Neither crosslinking or Intacs can be guaranteed to get rid of the need for glasses or contacts, but they can help patients see better with correction, have better quality of vision, and avoid the need for cornea transplant.
Hear Dr. Ambati explain changes in the cornea with Dr. Tom Miller on The Scope, the University of Utah Health Sciences Radio.
