The cornea is the clear window to the eye. Light rays passing through the cornea are refracted (or bent) by the cornea and then are refracted again as they pass through the crystalline lens on their way to the back of the eye (the retina).

The combined refractive capabilities of the cornea and the lens direct rays of light to focus sharply on the retina to produce a distinct image. Individuals who have an imprecise focusing mechanism, but who have a clear cornea and lens, can wear either contact lenses or glasses to direct an image crisply on the retina.
 
However, when the transparency of the cornea is compromised by disease or trauma, light rays are no longer allowed to travel unimpeded through the eye and a distortion in the visual image results. The cornea has in effect become a “dirty window” which cannot be treated with medication and a new cornea must be provided to restore vision. Some of the conditions that may require corneal transplant surgery include: keratoconus, corneal opacification or decompensation as a result of trauma or disease, and corneal decompensation (bullous keratopathy) as a result of previous intraocular surgery.

When corneal transplant surgery (otherwise known as penetrating keratoplasty) is indicated, the patient is registered with the Eye Bank. The Eye Bank is responsible for coordinating the collection and distribution of donated corneal tissue. The demand for corneas is so great that a patient may have to wait approximately four to eight weeks before tissue is available. We prefer to schedule the patient far enough in advance to achieve the highest priority for corneal tissue on the day of surgery. The corneas are obtained from deceased individuals who have either willed this tissue to the Eye Bank or have had their next of kin request a donation. The donated cornea is processed by the Eye Bank and placed in an enriched liquid medium that allows the tissue to remain viable for approximately one week prior to surgery (although most patients receive their cornea within 2 to 3 days from the time of death of the donor).

The donated corneal tissue is transferred to the patient as indicated below and then sutured in place using 10-0 nylon (a gauge thinner than a human hair).

 

The post-operative appearance of corneal transplant surgery is shown below. The suture is removed approximately one year after surgery. In some cases, a new sutureless transplant procedure called DSEK may be employed to achieve a more rapid visual recovery.