Corneal Transplant Surgery

WHAT IS A CONNEAL TRANSPLANT (KERATOCONUS)
This is an eye (ocular) disorder characterized by progressive thinning and changes in the shape of the cornea.

The cornea is the thin, clear outer layer of the eye and is normally rounded or dome-shaped. In those with keratoconus, slowly progressive thinning of the cornea causes a cone-shaped bulge to develop towards the center of the cornea in the areas of greatest thinning. Affected individuals develop blurry or distorted vision, sensitivity to light (photophobia), and additional vision problems.

CAUSES
The specific underlying cause is not fully understood and most likely the condition results from the interaction of multiple factors including genetic and environmental ones. One known factor to worsen cornea weakness is eye rubbing. In some cases, keratoconus may occur as part of a larger disorder.

SYMPTOMS
In the early stages, keratoconus may cause slightly blurred or distorted vision. As it progresses, vision may become more and more distorted and your eye glass prescription may change often.
An eye care professional can determine the presence of keratoconus using a slit lamp evaluation or by examining the surface of the cornea through corneal topography. Symptoms of keratoconus include:
• Distorted vision at all distances
• Increased sensitivity to bright light and glare, which can cause problems with night driving
• Sudden worsening or clouding of vision
• “Ghost” images – the appearance of several images when looking at one object
• Multiple changes to eyeglass prescription

DIAGNOSIS
Keratoconus may be diagnosed based upon a complete patient and family history and thorough eye examination. Such an examination may include evaluation of the external appearance of the eyes, visual acuity, eye movements, and visual fields; the use of a special, illuminated microscope that allows physicians to view the eye through high magnification (slit-lamp examination); and/or additional tests or procedures.
A specific imaging tests known as corneal topography is used to aid in a diagnosis of keratoconus, in part by detecting very early keratoconus where the corneal changes are not visible by a doctor looking at the eye (subclinical). This is sometimes referred to as “forme fruste” keratoconus. Corneal topography is an imaging study that uses an instrument to project a series of light rings onto the surface of the cornea. These rings of light are reflected back to the instrument and recorded. These recording can show changes in the shape and integrity of the cornea. Corneal topography is useful for determining the severity of keratoconus and monitoring the progression of the disorder.

TREATMENT
In the early stages, contact lenses or eyeglasses are an effective treatment for most cases of keratoconus.
As keratoconus progresses, other treatments may include:
• Custom soft contact lenses: specially designed soft contact lenses to help correct keratoconus
• Gas permeable (GP) lenses: GP lenses to help correct for the irregular cornea by covering, or masking, it with the smooth outer surface of the contact lens
• Scleral contact lenses: larger diameter lenses that vault over the entire cornea
• Corneal cross-linking (CXL): UV light and eye drops used to help stiffen your cornea
• Eye surgery in the small percentage of cases that contact lenses cannot correct, surgical options are available to repair the irregular shape of the eye. However, laser surgery is not an option, as there is a high probability of further damaging the cornea.