August 2019

IN FOCUS

Cataract Surgery Post-LVC
Setting the stage for successful cataract surgery in the prior refractive asurgery patient


by Liz Hillman EyeWorld Senior Staff Writer


Dr. Kugler uses iTrace, along with other technologies, to provide information about a post-refractive surgery patient’s lens density, light scatter, and visual quality.
Source: Lance Kugler, MD

 

You’ve got a patient in your chair. It’s time for preop diagnostic testing and a cataract surgery consult. This patient’s history shows prior refractive surgery.
“You need to start with the understanding that this patient has a different set of expectations and you’re challenged because of the prior refractive surgery. It’s more difficult to hit your refractive target—and there is more pain involved if you don’t,” said Kevin Waltz, MD.
There are special considerations at each stage—preop testing, patient expectations, IOL calculations and IOL selection, and postop enhancements—for prior refractive surgery patients seeking cataract surgery. Dr. Waltz, Lance Kugler, MD, Blake Williamson, MD, and Thomas Clinch, MD, shared how physicians can set themselves up for success at the preop stage.

Preoperative diagnostics

While most of the physicians said their preop testing is the same for every patient regardless of prior refractive surgery, they acknowledged they look at some elements more closely.
“I think it’s important to obtain topography from a few different devices to look for consistency and take advantage of the pros and cons of different devices,” Dr. Kugler said.
Dr. Williamson makes sure the refractive surgery procedure patients say they had matches up with their topography, as it can impact the IOL decision making.
Dr. Kugler mentioned using the HD Analyzer (Visiometrics) and iTrace (Tracey Technologies) because they provide information about lens density, light scatter, and the patient’s vision quality. Dr. Williamson said patients might come in for a LASIK touch-up but really have dysfunctional lens syndrome or early cataract; the HD Analyzer can identify this and show the patient that the lens is the source of their problem, not the cornea.
Dr. Kugler more closely analyzes the anterior and posterior curvature of the cornea in these patients, as well as the optical zone size and the epithelial map.
In addition to taking at least two topography measurements and comparing with the results obtained by optical biometry, Dr. Clinch said there is another important preoperative assessment. “I evaluate how well the patient perceived their day and night vision after LASIK. When patients describe excellent visual quality, I am more confident that they will adapt to the visual disturbances of diffractive IOLs,” he said .
Dr. Clinch said that during the counseling process, he explains to patients that he actually doesn’t operate on their vision. Cataract surgery changes the optics of their eye. “Vision is how the brain interprets the sensory input, and everyone’s brain is slightly differently,” he said.

Higher order aberrations

Most post-refractive patients are post-myopic LASIK, Dr. Waltz said, making spherical aberration relatively common. These patients, he noted, are used to the halo and ghosting caused by this aberration. Dr. Waltz said cataract surgery, at a minimum, can decrease the total amount of positive spherical aberration and minimal amounts can still be tolerated postop. It can also be treated with topography-guided PRK or LASIK or with aspheric IOLs, Dr. Kugler said. People who have had prior hyperopic LASIK tend to have negative spherical aberration.
“What is important is to measure the spherical aberration of the cornea so that you can get the net result of where the patient started and what you did to it,” Dr. Waltz added.
Things can get tricky with coma, which can occur if the ablation or incisions are decentered from the visual axis.
“If you have asymmetric higher order aberrations, like coma, they are very difficult to fix and need to be taken care of in terms of preop and postop discussions,” Dr. Waltz said.
Dr. Waltz emphasized that fixing sphere and cylinder are primary goals, followed by improving higher order aberrations.

Considering IOLs

Refractive surgery changes the anatomy of the eye, meaning it no longer fits the assumptions made in many IOL formulas, Dr. Kugler said. Post-refractive IOL calculation formulas attempt to correct those assumptions by making their own set of assumptions, which may or may not be accurate. For this reason, Dr. Kugler said he finds ORA (Alcon) helpful for some post-refractive patients.
Dr. Williamson said he relies on ORA, also using the SRK/T and Barrett True K formulas. Dr. Williamson said entering his post-refractive cataract surgery outcomes into ORA refined his results. He also likes that ORA includes the anterior and posterior cornea in its waveform. Dr. Williamson said if a patient has stable keratometry and limited dry eye and higher order aberrations, he would consider a presbyopia-correcting lens. He mostly uses the Symfony extended depth of focus lens (Johnson & Johnson Vision).
Dr. Clinch uses the Barrett formula and ORA. If there is a small discrepancy, he’ll go halfway between the two, but ORA plays a lesser role in the decision-making process. This is especially true in circumstances where he is uncertain whether the patient is fixating properly on the target. He also noted that ORA is most helpful for spherical power and cylinder axis; however, topography is the best predictor for cylindrical power.
For IOL selection, Dr. Clinch stratifies his post-myopic and post-hyperopic LASIK patients into different categories. Post-myopic LASIK patients are more likely to have smooth optical zones and positive spherical aberration. This makes diffractive IOL options an excellent option. Even for patients who were successful with monovision, he prefers bilateral diffractive IOLs. The result will be binocular distance function that improves depth perception as well as a greater range of intermediate to near vision. Negative spherical aberration is very common in post-hyperopic LASIK patients as well as more irregularity in the optical treatment zone. Dr. Clinch is less likely to use diffractive IOLs. He will either set both eyes for distance or will consider monovision after the patient is satisfied with distance vision in the dominant eye.
Dr. Clinch noted that he uses a femtosecond laser in all refractive cataract procedures. Femtosecond laser-created arcuate incisions will reduce or eliminate even small amounts of astigmatism, which is beneficial to the visual outcome; however, in post-LASIK patients, the corneal flap makes the effect of the incisions less predictable. For that reason, he is more aggressive in employing toric IOLs for slightly less than 1 D of astigmatism, especially against-the-rule.
In patients with coma, Dr. Waltz has experience with the IC-8 small aperture IOL (AcuFocus) and said it can fix that problem “spectacularly well.”
Overall, Dr. Kugler said one of the biggest considerations in his IOL selection is what his enhancement plan will be if he doesn’t nail the target.
In terms of monovision, if the patient already has it, both Dr. Kugler and Dr. Waltz said they will optimize it, as it’s likely the patient has adapted to it. Similarly, if a patient was using multifocal contacts and doing well, Dr. Waltz said he would be more likely to use a multifocal IOL, thinking it’s “better to improve on what the patient has than subject them to a whole new set of compromises.”

Setting expectations

“I think that more than ever the post-refractive patient is the one that requires the most time preoperatively,” Dr. Williamson said.
The “wow” factor they had if they had LASIK is more delayed with cataract surgery, and that expectation needs to be set, Dr. Williamson said. It could take weeks or, in the case of RK patients, months to reach complete healing and final refraction. As with any cataract surgery patient, Dr. Williamson emphasizes that the surgery will not return them to vision of their 20s.
Dr. Kugler echoed similar thoughts. “What I say is, ‘You had this done a long time ago and it’s been great for you. The downside of all these years of glasses-free vision is the calculations that we’re going to do for your lens at this stage are going to be more complicated,’” he said.
Dr. Kugler also sees many post-RK patients who think that cataract surgery is going to give them the vision all their LASIK friends have been raving about. However, even if you deliver a 20/20 J1 outcome, the RK patient often isn’t satisfied due to higher order aberrations, he said.
“The post-refractive RK patient’s expectations are not in line with what the surgeon can realistically deliver with the current technology. This is an area where small aperture lenses, such as the IC-8 and the Light Adjustable Lens [RxSight], may have a benefit,” Dr. Kugler said.
It’s not just what you say to the patient, however, it’s what they remember. Dr. Clinch estimated that patients only remember about one-third of what physicians tell them, and that is usually the information that they wanted to hear. Dr. Clinch uses repetition in counseling by technicians, counselors, and the surgeon to emphasize important information. He uses visual demonstrations by moving the patient’s hand to different positions to demonstrate the potential visual range. He also emphasizes a delay in visual rehabilitation for intermediate and near vision with a presbyopia-correcting lens. Patients often gain the visual function more quickly, which makes them feel like “overachievers,” Dr. Clinch said.
Dr. Waltz includes family members in consults because collectively, the patient and their family are more likely to remember what he says to expect postop.
In general, Dr. Waltz said “just about anything can happen postop as long as the patient is expecting it. Where it breaks down is when you surprise the patient.”

At a glance

• Preop diagnostics in post-refractive surgery patients require a closer look to make informed implant decisions.
• Prior refractive surgery makes IOL power calculations and hitting end targets trickier.
• Watch out for reduced visual quality due to higher order aberrations.
• Setting patient expectations with this group is more
important than ever because they are more likely to expect spectacle independence and a LASIK-like result.

Contact information

Clinch: tclinch@edow.com
Kugler: lkugler@kuglervision.com
Waltz: kwaltz56@gmail.com
Williamson: blakewilliamson@weceye.com

About the doctors

Thomas Clinch, MD
Eye Doctors of Washington
Washington, D.C.

Lance Kugler, MD
Kugler Vision
Assistant professor
Stanley M. Truhlsen Eye Institute
University of Nebraska
Medical Center
Omaha, Nebraska

Kevin Waltz, MD
President
Ophthalmic Research Consultants
Indianapolis

Blake Williamson, MD
Williamson Eye Center
Baton Rouge, Louisiana

Financial interests

Clinch: Alcon, Johnson & Johnson Vision
Kugler: Johnson & Johnson Vision, STAAR Surgical
Waltz: AcuFocus, Johnson & Johnson Vision
Williamson: Alcon, Johnson & Johnson Vision

Setting the stage for successful cataract surgery in the prior refractive asurgery patient Setting the stage for successful cataract surgery in the prior refractive asurgery patient
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