Contact Lens Management

Fitting Post-Corneal Transplant

The considerations, contact lens options and follow-up

Gregory W. DeNaeyer, O.D., F.A.A.O.

Although a successful corneal transplant provides the eye with a clear optical surface, the patient can be left with regular or irregular astigmatism, aphakia, anisometropia or traumatic mydriasis. (See “Corneal Transplant Surgery,” at the end.) The good news: Contact lens wear can address and resolve many of these residual anomalies, maximizing a patient's postoperative vision potential. In addition, these patients require premium services and materials that generate higher fees than your traditional contact lens wearers (See “Coding” below).

Here, I discuss the considerations in fitting these patients, the contact lens options and follow-up.

Considerations

The four considerations prior to fitting post-corneal transplant eyes:

1. Make sure the cornea is healthy and optically stable. The patient's cornea shouldn't be painful, red, edematous and/or iritic, as these are signs of host-graft rejection, glaucoma secondary to the corneal transplant or keratitis. Also, the patient should have a stable refractive status. Most corneal transplant eyes may be fit within six to 12 months postoperatively with the corneal surgeon's consent.
2. Perform topography. This is a must in order to evaluate the overall shape of the cornea, which will determine lens design selection. For example, if the graft/host surface is oblate, a reverse geometry lens design will provide the best fitting relationship.
3. Select a high oxygen permeable lens. These lenses decrease hypoxic-related neovascularization. This is imperative, as hypoxic-related neovascularization can increase the risk of host-graft rejection.¹
4. Remove broken or loose sutures prior to fitting. Broken or loose sutures act as an irritant, and, therefore, risk for neovascularization, especially into the suture tract. (NOTE: No special consideration is necessary for sutures that are buried and stable.)

Contact lens options

The two contact lens options for these patients:

► Soft contact lenses. These lenses are options for patients whose topography doesn't show moderate or severe post-corneal transplant irregular astigmatism. Toric lens designs are often needed to correct for astigmatism. For a patient whose topography shows mild irregular astigmatism, try using a custom specialty lens design, and increase the center thickness of the lens by up to 0.30 mm. This may mask surface irregularity and improve vision. Prosthetic lenses can be utilized to reduce glare and light sensitivity for those patients who have post-corneal transplant traumatic mydriasis. (See figure 1). Utilize a reverse geometry design to prevent excessive central vault in patients who have an oblate cornea. Using silicone hydrogel materials is recommended to reduce hypoxia and secondary neovascularization especially for lenses that have increased center thickness.
► GP contact lenses. Use these lenses on patients who develop post-surgical corneal irregularity. One study revealed approximately 22% of patients 12 months postoperatively required a rigid contact lens to improve vision in eyes not adequately corrected with spectacles.² Large diameter (10 mm to 11.5 mm) corneal GP lenses that have back surfaces often work well for these patients, as they allow an even weight distribution across an irregular corneal surface. Front surface toricity can be added to GP lenses to correct for residual lenticular astigmatism. Scleral lenses or hybrid designs are helpful when a corneal GP lens won't center properly, or when lens stability cannot be achieved. Finally, reverse geometry GP lens designs may be necessary to vault the mid-peripheral knee of an oblate graft. (See “GP Lens Options,” below.)

Figure 1: This soft toric prosthetic lens was fit on a patient who had traumatic mydriasis following PKP.

Follow-up

Post-corneal transplant contact lens wearers require more frequent follow-up than traditional contact lens patients, as hypoxic-related complications may either induce a host-graft rejection or corneal changes that are secondary to a GP lens that does not fit ideally on a severely irregular surface. Therefore, it's essential you examine their corneas at least twice a year to monitor for corneal neovascularization and any negative lens-to-cornea interaction that may cause keratitis. A corneal transplant's shape can change slowly through time, and this will most likely disrupt the contact lens-to-cornea fitting relationship, necessitating a refit.

Educate the patient that it's essential he discontinue lens wear and immediately contact you, should he experience pain, redness and/or decreased vision. Keep in mind that although any of these symptoms could be due to a contact lens-related infiltrative event or microbial keratitis, they could also be symptoms related to a host-graft rejection or glaucoma secondary to the corneal transplant.

Keratitis, host-graft rejection, or an IOP spike can all present with diffuse redness, corneal edema and iritis. Contact lens-related keratitis can be differentiated from host-graft rejection by the presence of corneal infiltrates. Checking the patient's IOP rules out secondary glaucoma.

Should the patient have a host-graft rejection, have him discontinue lens wear, prescribe hourly ophthalmic prednisolone, as it works as immunosuppressive therapy, and refer the patient back to his surgeon. (NOTE: The patient may have to use topical steroids for the rest of his life.) Should the patient have secondary glaucoma, prescribe topical glaucoma therapy, and monitor him for disease progression.

The visual rehabilitation of a patient who has sight-disabling corneal disease or scarring often does not end after a successful corneal transplant surgery, and sometimes contact lenses are necessary to achieve success. By providing contact lenses to these patients, you can improve their quality of life, while simultaneously improving your practice's bottom line. OM

1. Complications of Penetrating Keratoplasty. In: Kaufman H, ed. The Cornea. 2nd Ed. Boston, MA: Michael Hodkin;1998:868.
2. Price, FW. Whitson, WE. Marks, RG. Progression of visual acuity after penetrating keratoplasty. Ophthalmology. 1991 Aug;98(8):1177-85.
3. Yamaguchi, T. Negishi, K. Yamaguchi, K. et al. Comparison of anterior and posterior corneal surface irregularity in Descemet Stripping automated Endothelial Keratoplasty and Penetrating Keratoplasty. Cornea 2010 Oct;29(10):1086-90.