Preoperative evaluation key to corneal transplant outcomes

October 15, 2006

Philadelphia-Corneal transplantation requires a rigorous preoperative assessment that includes consideration of numerous factors before the surgery can be undertaken. Christopher Rapuano, MD, explained how to look in all segments of the eye and how to counsel the patient to get the best postoperative results.

"As in everything we do, the patient history is very important, as are the patient's symptoms. Are they considering a transplant because of decreased visual acuity or because of pain? The answer to that changes the factors that we think about and the timing of surgery," Dr. Rapuano explained. He is co-director, Cornea Service, co-chief, Refractive Surgery Department, Wills Eye Hospital, and professor of ophthalmology, Jefferson Medical College of Thomas Jefferson University, Philadelphia.

Along with this, the timing of the symptoms should be considered.

The presence of systemic disease, such as diabetes, Stevens-Johnson syndrome, or pemphigoid, is an important part of the history, as well as the patient's general health status and whether the patient is too ill to undergo surgery in a typical ambulatory surgical center.

Ocular disease limiting

The presence of ocular disease is a critical factor.

"Trauma, corneal lacerations, traumatic cataract, damage to the iris-among other factors-will affect some of the surgical options," Dr. Rapuano stated.

He also pointed out that access to the patient's medical records is helpful because they may contain data, such as the type of IOL implanted, the presence of a sutured IOL, or the IOL power, that may not be readily available because of corneal opacification.

"Of critical importance is the visual potential. Does the patient have the potential to achieve 20/20 vision or did this eye have a best-corrected vision of only 20/400?" he noted.

There are a number of steps that have to be followed before surgery, according to Dr. Rapuano. The patient must undergo a standard ophthalmic examination with measurement of corrected and uncorrected visual acuity and assessment of the pupils for an afferent pupillary defect.

The presence of external disease is another confounding factor that may result in exposure that affects the healing of the transplant.

"For example, if the patient has floppy eyelid syndrome, this is important to know and treat before the corneal transplantation to ensure higher chances of success," Dr. Rapuano explained. Another thing to look for is dry eye disease. Significant dry eye syndrome should be treated preoperatively to decrease the risk of problems after surgery.

An examination of the cornea may disclose scarring opacity and edema.

"The location of the scarring and whether it is anterior or full thickness should be determined. The considerations are the need to perform a penetrating (full thickness) graft or an anterior or posterior lamellar graft," he explained.

Severe thinning or thickening of the cornea and the presence of substantial corneal vascularization will affect the type and location of the graft.

"It is often helpful to determine the size of the graft needed at the slit lamp before surgery. In a patient with keratoconus, determining if the cone extends to the periphery can be done much more easily at the slit lamp before surgery," he advised.

He also evaluates the anterior chamber depth and looks for peripheral anterior synechiae, iridocorneal adhesions, vitreous prolapse, and elevated IOP to avoid any surprises intraoperatively.