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Several options available to fix refractive misses in cataract surgery
Denise M. Visco, MD, and Cathleen M. McCabe, MD, share how they approach cataract cases with less than ideal refractive outcomes.
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Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a joint society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.
As cataract surgery becomes more of a refractive procedure, patient expectations for a better refractive result have escalated. Dealing with refractive misses has become a source of frustration to many refractive cataract surgeons. This month, Denise M. Visco, MD, and Cathleen M. McCabe, MD, discuss their approaches to dealing with these problems. We hope you enjoy the discussion.
Kenneth A. Beckman, MD, FACS OSN CEDARS/ASPENS Debates Editor
Five-step process to decrease need for enhancements
Refractive eye surgery is any eye surgical procedure used to improve the refractive state of the eye, thereby decreasing dependency on glasses or contact lenses. With the arrival of femtosecond lasers into the cataract surgical market, continued innovation has improved the processes of refractive cataract surgery tremendously. But refractive surgical procedures hold expectations from patients that are different from standard cataract surgery. Often our work does not end after 1 day in the operating room, and fulfilling our commitments can be time-consuming and difficult.
Successful surgeons will generally maneuver through five basic steps with refractive cataract surgery. First, we educate patients. A connection and understanding between what patients want and what surgeons can do are extremely important. Most will agree enhancing an unrealistic expectation is virtually impossible. Second, we measure. Accuracy in treatment decisions relies on quality measurements with diagnostic devices, calculations using suitable formulas, and the proper applications of nomograms. Third, we treat. The more we can link our accurate measurements, formulas and nomograms to the treatment profile on the patient’s eye, the better the outcome. Fourth, we track. Known as a lagging indicator, outcomes must be tracked so we can make better decisions in the future. By tracking results and making adjustment to our processes, we can systematically decrease the number of misses. Lastly, we fix. Enhancements will be necessary for those patients who fall short of their target and are unhappy with the results of their refractive cataract surgery.
The fifth and final step of successful refractive surgery is the biggest hurdle for most surgeons. The patients who miss the mark will need to be made whole. If the percentage of enhancements is greater than 10%, the amount of work and cost to the practice is significant. Investing in high-quality diagnostic equipment that measures posterior corneal astigmatism and femtosecond technology with iris registration has helped to drive our enhancement rate down. Prior to Cassini TCA (i-Optics) and Lensar with Streamline (Lensar), we were at 9%, but now we are below 3%.
When surgeons perform enhancements, multiple options are available. My preference is PRK for small residual spherical refractive errors not tolerated by the patient. However, for undercorrection of cylinder in astigmatic incision patients, I will first reopen and/or extend the femto incisions for increased effect. If insufficient effect has been achieved after 6 weeks, then I will perform PRK for these patients as well. For my last 338 astigmatic incision eyes, I have satisfied two patients by reopening their astigmatic incisions and performed one PRK enhancement.
For toric IOL patients with undercorrected cylinder, a small percentage will have rotation of the IOL in the early post-op period, and I first try bringing these patients back to the OR for realignment. However, if my realignment attempt fails or if the patient is further than 6 weeks postop, I will perform PRK. For my last 73 toric IOLs, I have repositioned two lenses successfully and performed one PRK enhancement.
When a large refractive surprise occurs, surgeons generally know the first postoperative day or shortly thereafter. In these situations, IOL exchange is my preference over piggyback lenses. Because I use ORA (Alcon) intraoperatively for all of my refractive cataract patients, large postop refractive surprises just do not happen. For example, if ORA were to show me a post-IOL refraction of +4 D in a post-LASIK refractive cataract surgery patient, I would exchange the IOL before we finished the case.
One final point that makes everything more complicated: Dry eye disease is highly prevalent in our refractive cataract surgery patients and can confound postoperative results. I cannot stress enough to maximally treat dry eye disease and make postop patients wait until they are stable before considering enhancements. I have frequently held a patient’s hand for 6 months only to resolve dry eye issues and discover no enhancement is necessary. The patient was happy with me (eventually), and I was grateful the patient did not need further surgery.
Fortunately, there are many options for enhancing outcomes in refractive cataract surgery patients. Nevertheless, life is always better when you are right the first time. My strategy has been to systematically refine my five-step process to decrease the need for enhancements, and that would be my strongest recommendation. However, when necessary, further cornea-based incisional and laser refractive refinements are my go-to choices in moving an unhappy patient toward his or her emmetropic goal.
- For more information:
- Denise M. Visco, MD, can be reached at Eyes of York Cataract & Laser Center, 1880 Kenneth Road, Suite 1, York, PA 17408; email: dvisco@eyesofyork.com.
Disclosure: Visco reports she is a consultant and does research for i-Optics and Lensar.
Many factors to consider when correcting residual refractive error
Cataract surgery is increasingly a refractive procedure, with premium lens implantation requiring an even greater level of accuracy in postoperative refractive outcomes in order to meet patient expectations. For patients to realize the full visual benefit of a premium lens choice, the refractive result must be as close to emmetropia as possible. Although newer IOL formulas, such as the Barrett Universal II formula (which I use along with the Barrett toric calculator) or the Hill-RBF calculator, have decreased the average postoperative residual refractive error, sometimes a visually significant miss is present. In these cases, it is important to correct the error as precisely and expediently as possible. Each case must be approached uniquely, but there are some guiding principles that I follow when deciding on a treatment plan.
The first step is, of course, to talk with the patient to determine his or her level of satisfaction with the vision. It is important not to unnecessarily treat a happy patient if the patient is satisfied and able to function well. In other words, treat the patient, not the eye chart. Next, I make sure all other factors that can impact the vision and the accuracy of the refraction are treated. Ocular surface disease can have a significant impact on refractive error, and I begin by evaluating and addressing any issues such as meibomian gland dysfunction or tear deficiency. Any significant posterior capsule opacification is treated as well. I then obtain serial manifest refractions to ensure stability, as well as topography, Orbscan (Bausch + Lomb) and wavefront analysis.
For small residual astigmatism with a plano spherical equivalent, I will treat by opening laser corneal arcuate incisions if they are located on the meridian of the steep axis of the residual astigmatism. I use a Sinskey at the slit lamp with the patient under topical anesthesia to score the epithelium overlying the incision and sometimes also use jeweler’s forceps inserted deep in the incision and then opened in order to maximize the flattening effect. The amount of flattening is greater with longer incisions, those directly along the steep axis and ones located more centrally. I will repeat this procedure and/or lengthen the arc with a diamond blade at the slit lamp if some, but not all, of the desired flattening effect is achieved.
In the case of residual astigmatism and a plano spherical equivalent after a toric lens implantation, I will utilize astigmatismfix.com to determine if a simple return to the OR and rotation of the lens will solve the problem. If so, I may put a capsular tension ring in at the same time, especially in patients with longer axial lengths.
In cases in which the spherical equivalent is not plano, or if the above astigmatism correction is not practical (too much cylinder in a patient treated with corneal incisions) or was not successful, my next step is usually PRK with a standard ablation, as there is some risk of worsening of higher-order aberrations after customized ablation for patients with multifocal lenses. Also, in this older population with more ocular surface disease, PRK may have less risk of worsening dry eye. The exception to this is in patients with a need for faster visual recovery, especially if there is a larger hyperopic treatment. I also prefer to lift previous LASIK flaps rather than perform PRK over a LASIK flap as these patients can then enjoy rapid visual improvement. However, I do not lift small, decentered or very poorly visualized flaps or flaps with previous complications. I treat these cases with PRK over LASIK.
When there is a large refractive miss, such as after prior corneal refractive surgery (especially RK), I prefer to remove the lens and replace with the correct power lens. This is rarely necessary, even after RK, with the accuracy of modern formulas. My threshold for preferring a lens exchange over PRK is at about 1 D of residual hyperopia and slightly higher, around 1.75 D, for residual myopia. Most lenses can be safely removed many months, and sometimes years, after cataract surgery. If it looks like a lens exchange is a possibility, I will refrain from doing a YAG capsulotomy until after the exchange. It is possible to exchange a lens after a YAG capsulotomy, but I prefer to do a piggyback lens in these cases in order to minimize the risk of complications. Because premium IOLs are made of acrylic, a silicone three-piece lens is my lens of choice for the sulcus in order to minimize the risk of intralenticular opacities. Additionally, operating on the steep axis during an IOL exchange or piggyback lens implantation can decrease small residual amounts of astigmatism.
In summary, the choice of laser vision correction (LASIK vs. PRK), IOL exchange or piggyback IOL involves the consideration of many factors including the needs of the patient (regarding speed of visual recovery), the health of the eye (especially ocular surface disease) and specifics regarding the refractive miss. Optimizing comorbidities that also impact the quality of vision results in better planning in order to maximize the patient’s visual outcome.
- For more information:
- Cathleen M. McCabe, MD, can be reached at The Eye Associates, 2111 Bee Ridge Road, Sarasota, FL 34239; email: cmccabe@theeyeassociates.com.
Disclosure: McCabe reports she is a speaker and consultant for Alcon and Bausch + Lomb.