the contact lens exam
Examining Corneal Transplant Patients
BY LORETTA B. SZCZOTKA-FLYNN, OD, MS, FAAO
Contact lens practitioners may be the first to see a complication associated with a corneal allograft. Once the surgeon releases a patient for contact lens fitting, that patient may associate new symptoms with a newly dispensed contact lens. For that reason, a contact lens fitter must be acutely aware of the signs of graft rejection. Prompt management and return of the patient to the surgeon are key to successfully reversing a potentially sightthreatening complication.
Signs and Symptoms of Graft Rejection
The symptoms of graft rejection include redness, irritation, light sensitivity, foreign body sensation and/or blurred vision. Because graft rejection is an immune-mediated inflammatory process, it shares the same features as a general inflammatory response including vascular dilation and transudation, cellular infiltration and tissue edema.
Figure 1. Conjunctival redness and corneal edema associated with an endothelial rejection. Photo courtesy of Jonathan Lass, MD.
Cellular infiltration can occur as discrete sub-epithelial infiltrates or it can invade a specific portion of the corneal graft that is being rejected. If sub-epithelial infiltrates appear, they are usually about 0.5mm in size and are scattered throughout the donor tissue only. They are similar in appearance to infiltrates seen during epidemic keratoconjunctivitis. These infiltrates can occur alone or in combination with other forms of rejection. When they appear alone, they usually respond rapidly to topical steroids.
Different forms of rejection appear dependent on the layer of the donor cornea being rejected: epithelium, stroma or endothelium. The body gradually replaces donor epithelium with recipient epithelium, therefore this type of rejection would occur only in the earlier (first year) post-operative period.
Isolated stromal rejection can uncommonly occur; when it does it appears as stromal infiltrates and neovascularization.
The most common form of rejection is endothelial. You'll see keratic precipitates scattered across the endothelium or in linear form advancing in from the peripheral cornea (Khodadoust line). Once the endothelium is damaged, edema of the stromal and epithelial layers can occur and is a very prominent sign (Figure 1).
Educate Your Patients
Understanding patient symptoms is critical because in about 70 percent of corneal allograft rejections, patient symptoms precipitate the diagnosis. Thus, not only should we be comfortable and keen on recognizing these signs and symptoms, but we should remind patients to call if any such unusual symptoms develop, regardless of the new contact lens fit. CLS
Dr. Szczotka-Flynn is an associate professor at Case Western Reserve University Dept. of Ophthalmology and is director of the Contact Lens Service at University Hospitals of Cleveland.