Former LASIK Patients' Challenge to the Cataract Surgeon

Baby boomers' demand perfect vision and service. What are the challenges and rewards for cataract surgeons?

By Amin Ashrafzadeh, MD

Cataract surgery has undergone a major evolution over the past decade with the addition of new technologies such as the accommodating, pseudo-accommodating and astigmatically correcting intraocular lenses. Likewise, LASIK surgery has also enjoyed enormous popularity and evolution over the last 15 years. The transection of these two surgeries in the same population presents new challenges and opportunities. Accuracy of results, quality of results, customer service and management of expectations are all areas that will require our attention more and more each day. Here's a look at what we surgeons can expect, and the problems we will have to solve for our patients.

The New Cataract Patient

Barbara Millicent Roberts of Willows, Wisc. is 52 years old. She has had multiple careers — airline attendant, pilot, astronaut, NASCAR driver and also a doctor. She looks amazingly well and young and seems to have perfect vision. Just in case this little biography isn't ringing any bells, “Barbara Millicent Roberts” is the official name of the “Barbie” doll from Mattel Corporation. Many of our patients are living in not so dissimilar fashion. Many have had LASIK surgery and are now at the age where they have become presbyopic and are also developing cataracts. Can you imagine Barbie with reading glasses? Neither can many of those who grew up playing with Barbie and Ken.

So how many such folks are we talking about? The excimer laser has been FDA-approved for refractive surgery since 1995. That makes 16 years of history, with many of those years reporting more one million procedures per annum. Even in the economically challenging time that we are currently experiencing, in the year 2010 approximately 800,000 procedures were performed. That makes about 20 million laser refractive procedures in the United States alone. For years, the average age for a LASIK patient was late 30s; basically, people who could afford the procedure. These patients are the people with the means and demands — and now they are older. They hate the readers and are not used to hearing “no.” Furthermore, this recession is an absolute enigma to them, as is the notion of reining in their spending habits.

LASIK has been a great success and many of these patients have touted its results. Now that they are developing presbyopia and possibly cataracts too, they are looking toward the second miracle. Can we as ophthalmologists meet that high demand of perfect precision?

Can We Deliver?

Not so fast, partner! The accuracy of reaching within 0.5 diopters of the intended target for wavefront-guided IntraLase LASIK was 87%, and it was 98% for reaching within 1.0 diopters, in the Stanford LASIK eye surgery study.¹ The accuracy of reaching within 0.5 diopters of the intended target for cataract surgery is about 55% and it is 85% for reaching within 1.0 diopter (See Table 1). Why such a big difference?

In cataract surgery, many major variables play into an accurate calculation. The keratometry, axial length measurement, surgically induced astigmatism, surgical technique capsulorhexis), manufacturing lens tolerance of the IOL and many others lead to major variability. A more standard uniform wound incision and capsulorhexis, using the femtosecond laser, has led to a much more predictable and accurate effective lens position for the IOL and consequently the reach within 0.5 diopter of the intended target has risen from the 50-60% to 70-75% as reported by Robert Cionni at the 2011 AAO Annual Meeting in Orlando.²

That is great! And while I am grateful for increased accuracy, the truth is, that still leaves room for improvement. Ken Hoffer, MD, using the Orange intraoperative wavefront aberrometer from WaveTec Vision, was able to push his 56% within 0.5 diopter of intended target to 81%, according to data he presented in September at the 2011 ESCRS meeting.³ However, in eyes that are post-LASIK, his results even when using the Orange remained in the 50% range. Where do we go from these numbers? Enhancements!

Enhancements Come to Cataract Surgery

Enhancements are a standard element of discussion with refractive surgery. So why is it that although refractive laser procedure results are far more accurate than cataract surgery, enhancements are not a standard part of discussion for cataract surgeons? It is simply a matter of habit. Cataract surgeons have never had to really be accountable for their refractive results. Astigmatism and needs for presbyopic correction always gave the cataract surgeons the option of “get new glasses and all will be perfect.” Now that cataract surgeons are entering the realm of refractive surgery, glasses are no longer the only option, nor the preferred one. To avoid disappointment on the part of the patient and negative postoperative feedback, cataract surgeons need to get in the habit of discussing enhancements. With the ease of online review sites, social media and word of mouth, it is essential to avoid the negative feedback towards the technology and/or the surgeon.

My personal rate of enhancements for iLASIK (CustomVue, IntraLase LASIK) procedures is less than 5%. My personal rate of excimer laser use after premium IOLs, intended or unintended, is less than 15%. Without some reasonable numbers to discuss with the patients, it is hard to give them a sense of what they should expect. So far, I have had very understanding patients on both the iLASIK and the cataract surgery enhancement sides. I attribute that to my frank discussion preoperatively with my patients outlining the expectations along with the potential for enhancements when the case warrants.

When patients have previously had LASIK surgery, now all bets are off! I discuss with them the greater difficulty in properly calculating their IOL power and how they may need an enhancement. I inform them that there are currently more than 16 different formulas for estimating post-refractive IOL power, and the steps taken in calculating their IOL power, including the use of Haigis-L formula on the IOLMaster and the ASCRS.org post-refractive IOL calculator. I generally quote them a 25% chance for needing an enhancement.

All premium IOL patients need to be treated as LASIK and cataract work-up patients. Preoperative testing should include corneal topography, pachymetry, posterior corneal surface mapping, specular microscopy, macular OCT and ganglion cell layer analysis. If the patient is not a good LASIK candidate, he should not have a premium IOL, except possibly a toric IOL without enhancement.

So who does the enhancement? Either the primary surgeon, or a designee. Leaving the patient stranded is not only poor form, but also will kill the goose that lays the golden eggs. If you currently do not do LASIK or PRK, consider learning PRK. In many cases, though, it might be easier to simply pass these patients along to your local refractive colleague. If you have not supported that colleague over the years, it is easy to do so now with the corneal and refractive consults. Explain that, in exchange for your support, you expect equal support in caring for enhancements. Discuss hand-off of patients to the surgeon and back, cost and support structure. Is your refractive colleague willing to review your upcoming premium IOL case with you and lend you a review? It is amazing how a little friendly collegial support will spark something so beautiful. If you haven't given it a try, please do and surprise yourself!

The Post-LASIK Scenario

In case of post-LASIK eyes, several factors become paramount. A patient who has had a hyperopic LASIK treatment is probably not going to do well with current market multifocal IOLs due to the higher-order aberration profiles of the cornea and the implants. However, myopic LASIK treatments are fine with the current multifocal IOLs (Table 2). The main concern remains: Can the cornea withst and another enhancement and yet maintain stability? Patients with history of low refractive error correction will have a narrower range of results and may need small enhancements.

On the other hand, patients with previous high refractive treatment have a wider range of results and may need greater enhancement — yet they are the ones with the least corneal tissue available for enhancement. For every one diopter of refractive error, one may need up to 15 microns of stromal tissue for enhancement. Therefore a 3D refractive surprise could need 45 microns of stromal tissue for ablation. A patient who was previously a −8.0D myope and now has a corneal pachymetry of 400 microns, only has 350 microns of stromal tissue (less 50 microns for epithelium). This patient barely has any leftover tissue for an enhancement to be done safely. Tread cautiously.

Figure 1. When performing the clear corneal incision, take care not to intersect the LASIK flap.

A Rewarding — And Demanding — Demographic

With the baby boomers (born 1946–1964), now reaching presbyopia and cataract age, we are going to be facing a large population that want what they want and have the money to pay for it. They demand service and expect delivery. Among these patients, some might be preselected for premium IOLs — especially ones who have had LASIK. Although they pose a challenge, many have hated their glasses all their lives and now that they no longer have that perfect post-LASIK vision, they are most grateful to regain their visual freedom. They tend to be among some of the happiest group of patients. You will find that meeting their vision demands is well worthwhile. OM

Real-World Challenges

Case #1 In 2006, a 59-year-old female had LASIK surgery performed by me. At the time, we determined that monovision LASIK would best fit her lifestyle. Her refraction was +1.50 −0.75 x 055 OD → 20/15 and +1.13 −0.75 x 080 → 20/15. Her pachymetry was 545 µm OD and 532 µm OS. We aimed for a −1.50 sphere residual refractive error in the right eye. Her results six months postop were right on target with 20/50, J1+ OD and 20/15 OS uncorrected. However, she began to have significant myopic shift over the course of the next two years in her right eye. Two and a half years later, we did a cataract surgery for her right eye aiming for a −1.50 to −1.75 diopters post-operative refraction. I used the Atlas corneal topographer and the IOL Master (both Carl Zeiss Meditec) data to use in the ASCRS.org's calculator. The suggested results of the Masket and Haigis-L formula were used and resulted in a perfect −1.75 postoperative result. We chose a monofocal implant for her because of the sum of higher-order aberrations of the hyperopic treatment and the fact that multifocal implants may lead to poor visual quality. Case #2 Also in 2006, we performed LASIK on a 51-year-old female with a desired outcome of monovision. Her pre-LASIK refractions were −5.00 +0.75 x 090 OD → 20/15 and −5.00 +1.25 x 180 → 20/15 with pachymetry of 539 µm OD and 546 µm OS. The intended residual myopia for her left eye was −1.50 diopters. She had an excellent outcome; however, over the course of the next four years she presented progressive myopia with increasing nuclear sclerotic cataract OU. The Visante omni (Carl Zeiss Meditec) examination revealed a completely normal posterior corneal elevation. I used the Atlas and the IOL Master data to input into to the ASCRS.org's calculator. Given that she had a myopic ablation, her higher-order aberrations were compatible with multifocal IOLs. We chose a Tecnis Multifocal IOL for her and she had an outcome of 20/15 OU, J1+ uncorrected. She strongly prefers the multifocal implants over her previous monovision.

References

1. Manche EE. LASIK: Wavefront-Guided Versus Wavefront-Optimized Technology. Cataract and Refractive Surgery Today. August 2011: 50-52.
2. Cionni RJ. New Technology in Cataract Surgery. Presented at: 2011 Annual Meeting of the American Academy of Ophthalmology. Monday, Oct. 24, 2011.
3. Hoffer K. IOL Power Calculation. Presented at: XXIX Congress of the European Society of Cataract and Refractive Surgery, Vienna. Sept. 17-21, 2011.

Amin Ashrafzadeh, MD (Dr. Ash) is a cataract, cornea and refractive surgeon in private practice in Modesto and Turlock, Calif. He is a consultant to Carl Zeiss Meditec. Dr. Ash may be reached at DrAsh@ModestoEyeCenter.com.