Although LASIK, a piggyback IOL, or an IOL exchange may successfully treat refractive errors in a pseudophakic eye, there are many patients for whom RK provides the most efficient, and in some instances, the safest option. Two cases that I treated illustrate how RK can produce an excellent outcome.
An 81-year-old white female with lifelong myopia and an axial length of 27.5 D underwent uneventful cataract and IOL implantation surgery. The patient's preoperative A-scan indicated the presence of a posterior staphyloma, and I counseled her as to the possible inaccuracy of her refractive outcome. I selected a postoperative target refraction of -1.00 D. At 2 weeks following the patient's uneventful cataract surgery, her postoperative refraction was -3.50 D. The patient expressed a desire to reduce her myopia, and after discussing the surgical options with her, I performed a four-cut mini-RK. Four days later, the patient's visual acuity was 20/30 with -1.25 D sphere, and she has maintained this refraction for 2 years.
RK may also be advisable for myopic patients with deficient tear production, as in the following case report. A 45-year-old white female was evaluated for possible LASIK OD. Her refraction was -5.00 D OD and plano OS, and she functioned with monovision. However, the patient wished to decrease the myopia OD in order to read at approximately 20 inches. I performed a routine preoperative evaluation including a Schirmer's test, which indicated 1 mm of wetting at 5 minutes (Schirmer No. 1 and No. 2). I placed an inferior punctal plug, repeated the Schirmer's test, and found the wetting to remain low (1.5 mm). After the patient and I discussed the potential complications of LASIK in the presence of deficient tear production, she elected to undergo RK. Four days following the surgery, her refraction was -1.75 D, and has remained so for 4 months.
RK is most effective in older patients because a greater refractive effect is obtained with the procedure. In addition, many older patients are suboptimal candidates for laser refractive procedures because of dry eye and/or epithelial fragility problems. RK seems to be less adversely affected by dry eye conditions than LASIK or PRK. It induces less denervation of the cornea than laser refractive procedures, and requires much less epithelial healing than PRK. This is not to say that elderly patients undergoing RK may not require prolonged use of wetting agents following their procedure, but severe epithelial problems are quite rare in any age group following RK.
Richard J. Mackool, MD, is Director of The Mackool Eye Institute and Laser Center in Astoria, New York. Dr. Mackool may be reached at (718) 728-3400; email@example.com