contact lens Q&A
Contact Lenses After Penetrating Keratoplasty
BY JAMES V. AQUAVELLA, MD
You may be wondering how to manage older patients who have undergone penetrating keratoplasty. Here's how to match those older patients with contact lenses and how to deal with any problems that may arise.
When should you prescribe contact lenses following penetrating keratoplasty?
ANSWER: Once healing is established and sutures have been removed, you can perform a definitive stable refraction. If the patient is able to achieve comfortable visual acuity with spectacle correction, then it's not necessary to consider contact lenses.
Young people who have had transplants, such as keratoconus patients, even those with small degrees of refractive cylinder or anisometropia, may do well with contact lenses since they were probably used to wearing them preoperatively. These individuals are able to insert and remove their lenses, but you must compare the quality of the visual acuity they achieve with spectacles versus that with contact lenses.
Older individuals who have not previously worn contact lenses and who may be intimidated by the insertion and removal process may also not have the necessary manual dexterity for contact lens wear. Following keratoplasty for bullous keratopathy, there may be large amounts (>4.00D) of postoperative cylinder or anisometropia, ruling out spectacle correction. A rigid gas permeable (RGP) contact lens is easy to fit and is the procedure of choice for rapid rehabilitation. If an elderly patient can wear contact lenses comfortably and without insertion and removal difficulties, you may use this simple and easy method to achieve and maintain good visual acuity. However, keep in mind that the older patient population often presents with quantitative tear film dysfunction, which renders contact lens wear even more problematic. The reduction in the aqueous content of tears further increases lipo-proteinaceous debris. Discomfort, reduced acuity and curtailed wearing time are common.
Ancillary measures, such as frequent instillation of artificial tears and punctal occlusion, may be beneficial. Even after a successful initial fit, be sure to check the lens parameters and corneal curvature at six-month intervals to catch any delayed corneal changes which would necessitate refitting the patient.
If the patient cannot wear RGP lenses, try a hydrophilic lens. Increased comfort and the prospect of extended wear will be attractive to the patient. A toric lens is often necessary, which increases the cost to the patient. Some patients must use prophylactic antibiotics and maintain a reasonable removing, cleaning and disinfecting schedule over the long term. Consider refractive surgery only when spectacle correction, rigid gas permeable contact lenses and hydrophilic lenses are not reasonable alternatives.
Astigmatic keratotomy (AK) and photorefractive keratectomy (PRK) are useful procedures, but particularly to the elderly postcorneal transplant population as a means to achieve comfortable vision without the necessity of contact lenses. When you recognize that emmetropia is not necessary, you'll see that the goal is to reduce the astigmatism or anisometropia to a level where comfortable binocular spectacle acuity is possible. Most of these patients need vision to maintain their lifestyle but don't need or want to discard their spectacles.
Dealing with the elderly post-keratoplasty patient can be time-consuming and is usually not financially rewarding. However, these are minor factors compared to the enormous benefits that are associated with a well-fitted contact lens. CLS
Dr. Aquavella is chairman of the Genesee Valley Eye Institute and director of the corneal research lab at the University of Rochester.