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Refractive lens exchange not another name for cataract surgery
Kevin L. Waltz, OD, MD, offers lessons on controlling astigmatism in RLE patients.
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Last month, Louis D. “Skip” Nichamin, MD, described a comprehensive approach to astigmatism management for refractive lens exchange patients. The mainstay of the approach is limbal astigmatic keratotomy performed at the time of lens exchange. As Skip mentioned, astigmatic keratotomy was moved from the 6 to 7 mm optical zone to the limbus in the mid-90s initially by Hollis. As one who has been performing astigmatic keratotomy regularly on refractive cataract patients since 1985, I experienced firsthand the improvement in accuracy and stability that resulted from this shift away from the cornea to the limbus. Within that change in astigmatic keratotomy lies an important point.
My initial decade of experience with corneal astigmatic keratotomy (typically at the 7 mm optical zone) taught me that the central cornea can respond quite variably to our attempts at changing its shape. I increasingly began to understand that despite our best efforts, the central corneal shape often rests where it will, not always where we will. I learned to better understand and respect some of the cornea’s idiosyncrasies and independent ways. I learned not to try too much and often to just let it be. I am sure that it is this principle and the corneal instincts that it nurtured that led me to treat with suspicion the initial claims and recommended treatment ranges of PRK and then LASIK advocates. It was this principle that continued to pull me toward a lens-based approach for refractive surgery. I will come back to this in next month’s issue, which is dedicated to lens-based refractive surgery.
In today’s column, Kevin Waltz, OD, MD, continues the discussion of astigmatism management from a different perspective. Using three case studies, Kevin illustrates some important lessons for surgeons beginning astigmatism management in earnest.
This article is also important for a different reason. Kevin is an experienced refractive lens exchange surgeon who has learned firsthand that “RLE is a process, not a procedure.” He emphasizes that RLE is not simply cataract surgery by another name. Anyone hoping to be successful with RLE must come to fully understand this important principle. Thank you, Kevin, for a valuable contribution. Your experience is clearly displayed in your words here.
Next month:
The most efficient techniques for lens removal in RLE.
by Kevin L. Waltz, OD, MD
Special to Ocular Surgery News
Refractive lens exchange is a rewarding procedure for both the patient and the doctor. It allows the surgeon to efficiently and effectively correct otherwise untreatable refractive errors, such as extreme hyperopia. RLE uses the same successful and familiar techniques developed for cataract surgery to treat refractive errors. As a result, one might think RLE is simply cataract surgery by another name. It is not. A casual attitude toward astigmatism and lens surgery can create a serious trap for the surgeon who thinks RLE is simply cataract surgery. Presented here is an approach to astigmatism that will benefit cataract patients and RLE patients.
Expectations
RLE is a process, not a procedure. The process begins as soon as the patient contacts my office requesting a consultation; however, the process has no clear ending in my mind or in the patient’s mind. After RLE, patients expect to be less dependent on glasses for the remainder of their lives. The successful RLE patient is willing to do what is necessary to accomplish this goal. In return, he wants to know from the surgeon and staff how much time and money it will take to accomplish this goal. It is important for the patient to know this prospectively, before any type of surgery. Undercorrected astigmatism is one of the most common sources of unmet patient expectations after RLE, and it must be addressed appropriately as part of the process.
Just as the RLE patient assumes some risk with surgery, it is equally important, from the patient’s perspective, for the surgeon to assume some risk. Patients believe that a surgeon who is willing to assume some risk is more likely to deliver the results they want in a timely, efficient manner. In contrast, cataract patients understand they have a disease. Cataract patients are more likely to be tolerant of perceived or real inefficient use of time and effort. Undercorrected astigmatism is one of the most common reasons for an enhancement surgery after primary RLE. Likewise, it is a common component of a typical postoperative glasses prescription or refractive “enhancement” after cataract surgery.
The cataract patient is usually willing to wear glasses most if not all of the time after surgery. The RLE patient is not. The RLE patient considers glasses a treatment failure. Often the cataract surgeon forgets the extent to which glasses are used to “enhance” surgical outcomes. Glasses do a great job of correcting lower-order aberrations such as sphere and cylinder. Residual spherical error is usually related to biometry or IOL calculation challenges, such as a small, hyperopic eye with a normal anterior chamber size. Residual astigmatism is usually due to not treating it or undertreating it. After conducting several informal surveys, I believe only one in six surgeons in the United States surgically treats astigmatism before, during or after cataract surgery. A cataract surgeon must first learn to treat astigmatism routinely, effectively and effortlessly to become a successful refractive lens surgeon.
Treating astigmatism
Learning to treat astigmatism is a straight-forward process. Approximately 7% of cataract patients have 2 D or more of astigmatism preoperatively. These patients are ideal candidates for corneal relaxing incisions at the time of cataract surgery. They will almost certainly benefit from any effort the surgeon makes to decrease their astigmatism and are unlikely to be harmed by the surgeon’s efforts. Taking a course on corneal relaxing incisions may be beneficial. The necessary surgical equipment can be purchased at a trade show. I also strongly recommend a topographer. After becoming comfortable with decreasing larger amounts of astigmatism, practice eliminating smaller amounts. The surgeon will then learn to optimize his own nomogram for smaller and more precise amounts of cylinder correction.
After becoming an accomplished astigmatism surgeon, consider charging patients for the value-added benefit of astigmatism control at the time of cataract surgery. Astigmatism control at the time of cataract surgery is refractive surgery. As such, it is a noncovered benefit under Medicare and most insurance plans. Charging patients for this benefit will help not only the surgeon, but it also helps the staff become more comfortable charging for refractive surgery services in general. This transition should not be rushed. In my practice, it took several years to fully develop.
Successfully treating the RLE patient’s astigmatism is the ultimate goal. The refractive lens surgeon needs to be able to recognize and treat astigmatism in an efficient and effective manner. There are several ways to accomplish this. Corneal relaxing incisions are the most common and cost-effective method for correcting astigmatism. These typically are performed at the time of surgery, but they can be performed after lens surgery as well. Sometimes, LASIK is performed before lens surgery for extreme amounts of cylinder. Here are three examples of astigmatism control and the lessons learned from them.
Examples
A 48-year-old woman with +3.50 +3.50 3 090 in both eyes presented for RLE. She had 4.25 D of corneal astigmatism with a wide, symmetrical bow tie. Corneal relaxing incisions would not consistently treat this amount of astigmatism. Consequently, LASIK was performed 1 month before the lens surgery. All of the corneal astigmatism was corrected with LASIK with an average corneal power change of zero (Figure 1). The patient had Array IOLs implanted bilaterally. Postoperatively, the patient had uncorrected distance visual acuity of 20/20 and uncorrected near visual acuity of J2 in both eyes. Using LASIK as the primary method to treat corneal cylinder doubles the number of surgeries for the patient but significantly decreases the net spherical aberration of the eye after the process is complete. This is the result of exaggerated flattening of the corneal periphery.
A 54-year-old man with a moderate amount of hyperopia and approximately 3 D of corneal astigmatism presented for RLE. Lens surgery combined with corneal relaxing incisions was performed without complication in each eye. Unfortunately, his astigmatism correction was inadequate. Large, wide bow tie patterns on topography suggest that something other than corneal relaxing incisions will be needed for adequate astigmatism correction. PRK was performed postoperatively to correct the residual astigmatism. This resulted in both a subjective and objective improvement in the patient’s vision.
A 62-year-old man presented with cataracts, moderate myopia and 3 D of astigmatism. He wanted to decrease his dependency on glasses as much as possible. He had a retinal detachment in his left eye successfully repaired years ago. He worked as an engineer with IBM. I have included this patient in a discussion of RLE because he was a very challenging cataract patient. His expectations were similar to those of a refractive patient. I would not have been able to satisfy this patient before my experience with RLE.
Successful cataract surgery with paired 80° corneal relaxing incisions was performed in each eye with placement of Array IOLs. Most of the astigmatism was corrected with the initial relaxing incisions. However, some irregular astigmatism resulted in the right eye. He stated his vision was not adequate for reading without correction. He desired further refractive surgery. Asymmetrically coupled, paired corneal relaxing incisions 3 mm long with an 8 mm optical zone were performed at the slit lamp to improve the irregular astigmatism. The pre- and postoperative topographies with the difference map are shown in Figure 3. Notice the very tight scale to demonstrate the relatively small differences. These small differences allowed this patient to read most of the time without glasses.
(All images courtesy of Kevin L. Waltz, OD, MD.) |
Common ground
Refractive lens surgery is an exciting, developing area for the cataract and refractive surgeon. Successful RLE requires elements of both disciplines. Astigmatism control is one area that clearly benefits from a refractive surgery approach to lenticular surgery. LASIK surgeons must also create or maintain lenticular surgery skills. Both disciplines will continue to move toward common ground as we search for ways to satisfy our patients’ needs.
I would like to thank R. Bruce Wallace, MD, FACS, and Michael B. Brenner, MD, FICS. They have educated me about astigmatism and its treatment, thereby improving my surgical outcomes.
For Your Information:
- Kevin L. Waltz, OD, MD, can be reached at 8103 Clear Vista Parkway, Indianapolis, IN 46256; 317-845-9488; fax: 317-579-7440; e-mail: klwaltz@aol.com.