Scope of refractive surgery blooms beyond simply LASIK

Refractive surgery is not just LASIK surgery anymore.

Surgeons who want to be true refractive surgeons and help patients see better without glasses or contact lenses now have more opportunities than ever to obtain good outcomes using a variety of refractive procedures — seven in all.

“If you are a lead refractive surgeon, you better know all seven procedures and who is a candidate for each one,” OSN Refractive Surgery Section Editor Daniel S. Durrie, MD, said.

Image: Kenny Johnson Photography

PRK was first performed in 1987, and LASIK was approved by the FDA in 1999. The field of refractive surgery also now includes phakic IOLs, refractive lens exchange (RLE), corneal inlays, small incision lenticule extraction (SMILE) and corneal cross-linking.

“It’s just an amazing time now to be a refractive surgeon,” Durrie said. “Through a tremendous amount of development and the introduction of lasers, computers, outcomes analysis and especially diagnostic equipment, patients interested in seeing better than with glasses and contact lenses can now have sophisticated diagnostic tests and evaluation to find out if they are truly good candidates for refractive procedures, and if they are, determine which of the seven procedures they qualify for.”

Furthermore, in many cases, patients have fewer dry eye symptoms and night vision problems than they experienced with contact lenses, Durrie said.

FDA approvals spawn growth

Several significant FDA approvals for refractive surgery have occurred over the past 3 years, after a hiatus of more than a decade, and have affirmed the safety and efficacy of these procedures and boosted growth in the refractive surgery space.

In 2015, the Visx Star S4 IR excimer laser was FDA approved to treat myopia and astigmatism with the iDesign Advanced WaveScan Studio system and the CustomVue procedure. Both systems are from Abbott Medical Optics.

Then, in November 2016, the iDesign system was approved for treating mixed astigmatism.

“Not only did the clinical trial for each of these two approvals show that LASIK was safe and effective, but patients also reported improved symptoms of dry eye, night vision, halos and glare,” Durrie said.

In addition, Alcon/Novartis introduced the WaveLight platform Contoura Vision System for topography-guided custom ablation treatment in November 2015; the technology had garnered FDA approval in 2013.

“That clinical trial also demonstrated that patients reported better outcomes after surgery than before,” Durrie said.

These three FDA approvals “fit the overall narrative of modern laser surgery,” according to Durrie, who added that software for these technologies has now been upgraded to produce even better diagnostics and outcomes.

“We have learned who are the very best candidates for surgery,” Durrie said. Patients should have healthy eyes and stable vision. They should be motivated. And they should be well educated about the procedure. Surgical candidates who are younger than 30 years now represent the prime growth area for refractive surgery, he said.

When Durrie first started performing laser refractive procedures in the early 1990s, the realistic goal was to attain 20/40 vision — good enough to pass a driver’s test. Now, patients who are identified as “extremely good candidates” for refractive surgery can expect to see better than they would with their glasses and contacts, with close to 100% of these patients achieving 20/20 vision after the procedure and good follow-up, he said.

Today, patients can expect LASIK “to be a lifestyle enhancement procedure,” Durrie said.

Options for ocular maturity

Beyond LASIK being performed in the burgeoning under-30 set, refractive surgeons are meeting the needs of patients whose eyes are in various stages of vision development.

In addition to LASIK and PRK, phakic IOL implantation and SMILE are suitable procedures for treating myopia in patients who have reached “ocular maturity,” according to Gregory D. Parkhurst, MD, president of the Refractive Surgery Alliance. Ocular maturity is the first of three milestones of human vision development, which also includes presbyopia and cataract, Parkhurst explained.

FDA-approved phakic IOLs include STAAR Surgical’s Visian ICL, a Collamer lens implanted in the posterior chamber in patients with –3 D to –20 D of myopia, and Abbott Medical Optics’ Verisyse lens, which is implanted in the anterior chamber in patients with –5 D to –20 D of myopia.

Screening for patient suitability for a phakic IOL is slightly different from screening for LASIK or cataract surgery, according to Parkhurst. A modest investment in special forceps to load the lens properly and access to an operating microscope are also both needed, he said.

If the only procedure to be performed is implantation of a phakic IOL, then patients must have less than about 2 D of astigmatism because there is not yet a toric phakic IOL approved in the U.S., Parkhurst said.

For patients who have both high myopia and significant astigmatism, Parkhurst often uses a combination bioptics approach, that is, laser vision correction for the cylinder and phakic IOL for the myopia.

Overall, results for phakic IOLs are excellent and are not “dose-dependent,” according to Parkhurst.

“In other words, a –15 D patient can expect to have the same uncorrected results as a –3 D patient,” he said.

Parkhurst is the author of a prospective comparative study of 50 patients; half underwent wavefront-optimized LASIK and the other half received phakic IOLs. Both groups achieved comparable uncorrected acuity results at 3 months postop, he said — 20/20 or better in 96% of phakic IOL cases and 94% for LASIK.

For Parkhurst, the key to great results is to size the lens correctly.

To offer SMILE, on the other hand, a refractive surgeon must invest in a femtosecond laser that has the ability to perform the procedure.

“Right now, there is only one FDA-approved laser that meets that criterion, the Zeiss VisuMax laser, which is a sizable investment,” Parkhurst said. “But the equipment can also be used to make LASIK flaps.”

The VisuMax laser was approved for SMILE in September 2016; however, approval is restricted to treating myopia. “These are low and moderate myopes without significant astigmatism,” Parkhurst said.

Like outcomes with phakic IOLs, results of SMILE are also “excellent” and similar to those obtained with LASIK, according to Parkhurst.

“Still, there is somewhat of a learning curve for docking and centration of the laser on the patient’s eye; hence, it is advisable to use the laser to perform several LASIK flaps before advancing to SMILE,” he said.

However, if the patient cannot fixate and the laser cannot be centered properly, then the surgeon needs to know when to abort the procedure and switch to LASIK, Parkhurst said.

Corneal inlays

The past few years have seen the advent of numerous technologies that treat presbyopia, the second milestone in the spectrum of vision development.

“Corneal inlays are a welcome addition,” R. Luke Rebenitsch, MD, a refractive surgeon at ClearSight Center in Oklahoma City, said. “Yet offering them requires a different approach than traditional laser vision correction or premium lens surgery.”

Rebenitsch said there is a learning curve for performing corneal inlay procedures, as well as in patient selection and education.

“A patient undergoing this procedure must be observed more closely during the postoperative period than either laser vision correction or lens-based surgery,” he said.

Furthermore, there is the capital investment of the inlays and new diagnostic equipment.

“However, even given these considerations, inlays can be a great practice builder, if offered correctly,” Rebenitsch said.

Presently, there are two FDA-approved inlays: Kamra (AcuFocus), approved in April 2015, and Raindrop (ReVision Optics), approved in June 2016.

“Kamra improves depth of focus through the pinhole effect,” Rebenitsch said. Raindrop, in contrast, increases depth of focus “through the creation of a small zone of increased power over the visual axis, thereby creating negative spherical aberration.”

Patient selection is critical.

“Although these inlays can provide an increased depth of focus with minimal effect on distance vision, the process is more involved than with more traditional techniques of laser vision correction blended/monovision and refractive lens exchanges,” he said. “The ideal patient is one who fully understands the benefit of corneal inlays and is able to adjust to the longer healing process and protracted drop schedule.”

Often, patients who have had previous monovision can potentially improve their distance vision and stereopsis while also increasing their near vision with inlays, according to Rebenitsch.

Results for the two inlays are “excellent,” Rebenitsch said. Both inlays, though, have specific refractions that allow for ideal results.

“Kamra achieves the best results at a refraction of –1 D to –0.75 D, while Raindrop achieves the best results at a refraction of around +0.25,” he said.

The investigational device exemption (IDE) study for the Raindrop showed that stable eyes attained a mean monocular uncorrected near visual acuity (UNVA) between 20/20 and 20/25, while maintaining an uncorrected distance visual acuity (UDVA) between 20/25 and 20/32.

“Variability was also minimal, with nearly all patients (95.1%) achieving UNVA of 20/32 or better,” Rebenitsch said.

Moreover, the need to reverse the procedure and remove the Raindrop inlay was uncommon, and in those eyes that did require explantation, all achieved best distance visual acuity of 20/25 or better, Rebenitsch said.

The IDE study for the Kamra demonstrated that stable eyes attained a mean monocular UNVA between 20/25 and 20/32, while maintaining a monocular UDVA of approximately 20/20.

“But in the surgical subgroup of patients who had pockets created with a tighter spot-line separation, as well as those who were slightly myopic, results were even better,” Rebenitsch said.

Similar to the Raindrop, removal of the Kamra was infrequent.

“With newer techniques, the rate of Kamra removal has diminished even further,” Rebenitsch said.

One of the most common complications of corneal inlays is haze, which can usually be managed without sequelae, if caught early, according to Rebenitsch.

“Typically, a round of steroids with a slow taper is all that is required to avoid explantation,” he said.

Patients who do not qualify for either of the corneal inlays are typically still motivated to be as spectacle-independent as possible, Rebenitsch said.

“In our practice, we have seen an exponential increase in laser vision correction monovision, refractive lens exchange and cataract surgery. These additional procedures alone have paid for the equipment and advertising of corneal inlays,” he said.

Corneal cross-linking and PRK

OSN Technology Section Editor William B. Trattler, MD, said corneal collagen cross-linking is an essential component of a refractive surgeon’s practice, as is PRK.

In 2016, Avedro received FDA approval of its KXL System with an ultraviolet light source, plus two photoenhancers, for corneal collagen cross-linking to treat both progressive keratoconus and post-LASIK ectasia. Often, patient consults for refractive surgery reveal early keratoconus, Trattler said.

Besides treating keratoconus and ectasia, cross-linking can benefit patients with pellucid marginal degeneration or ectasia following other corneal surgeries, including RK, PRK and corneal transplants, according to Trattler.

After cross-linking, there is typically stabilization of the corneal shape and vision. Over 1 to 3 years after the procedure, patients will often show improvement in their corneal shape and report improved quality of vision, according to Trattler. “But the results are variable,” he said.

Trattler said the FDA-approved epithelium-off procedure entails removal of the epithelium, application of riboflavin drops for 30 minutes, followed by slit lamp examination to ensure adequate riboflavin loading of the cornea and then 30 minutes of ultraviolet light exposure.

“In 97% of patients, only one treatment is required,” Trattler said. However, there will be a small percentage of patients in whom a second cross-linking treatment will be required to stabilize the corneal shape.

To accelerate the healing process, Trattler recommended removing the minimum amount of epithelium necessary, maximizing the ocular surface health and minimizing the use of medications that may delay healing.

According to Trattler, the good news for PRK, an excimer laser procedure that reshapes the cornea, is that the learning curve is “extremely short” and there are many open-access laser vision centers across the country, where surgeons, for a fee, can be trained and treat patients.

Reshaping the cornea in appropriate candidates for PRK will reduce their need for contact lenses or glasses to correct refractive error, according to Trattler.

“These can be patients who have myopia, hyperopia and/or astigmatism,” he said.

Another recent FDA approval was for PRK with the WaveLight Allegretto platform for myopia and astigmatism. Results were excellent, with 94% of eyes seeing 20/20 or better without enhancements, according to Durrie.

Outcomes for hyperopia, though, may not be quite as good as for myopia, Trattler said. There is a risk of corneal haze in patients who have undergone previous corneal surgeries or higher levels of treatment.

“In these higher-risk cases, we often apply 0.02% mitomycin C on the cornea for 12 to 30 seconds before placing the bandage contact lens,” Trattler said.

For both PRK and epi-off cross-linking, one of the greatest liabilities is infection, for which patients are given a prophylactic antibiotic for use until the epithelium has healed. “The epithelium typically heals within 3 to 5 days,” Trattler said.

Like for corneal cross-linking, the surgeon should spare as much of the epithelium as possible for increased healing, Trattler said. New innovations in cross-linking, such as entirely preserving the epithelium and incorporating different UV light parameters, “should continue to improve outcomes and reduce risk,” Trattler said.

Refractive lens exchange

Present technology allows surgeons to discuss a lens-based option such as RLE for refractive correction in patients with dysfunctional lens syndrome.

“If you have a patient who is 54 with some early dysfunctional lens changes, you can perform LASIK, but most likely that patient will be back in 5 to 8 years complaining of worsening vision because the lens has changed,” Jason E. Stahl, MD, a surgeon at Durrie Vision, said.

“You need to be very good at hitting refractive outcomes” when performing RLE, and there will be times when enhancements are needed to meet patient expectations, he said. To get optimal results with lens replacement, surgeons need to have access to corneal laser technology to “optimize” the results as needed.

Image: Stahl JE

RLE is a four-in-one procedure that corrects refractive error for clear distance vision, corrects near vision, obviates the need for cataract surgery and stabilizes the optical system, according to Stahl.

“The optical system is stabilized because the only thing unstable is the [natural] lens,” Stahl said.

Stahl described dysfunctional lens syndrome as a progression of the natural lens in three stages: a stiffening of the lens (presbyopia) in patients in their 40s to early 50s, degradation of the lens optics causing forward light scatter in patients in their 50s and 60s, and a clouded lens (cataract) in patients in their 60s and beyond.

“With diagnostics, we can visualize and measure these changes and then educate our patients why a lens-based procedure is the best option for correcting their vision,” Stahl said.

The Scheimpflug photography of the Oculus Pentacam provides lens densitometry that objectively measures forward light scatter associated with dysfunctional lens syndrome resulting in decreased image quality.

The Visiometrics HD Analyzer is a double-pass wavefront device that captures and quantifies forward light scatter, or the ocular scatter index, and simulates the point spread function on the retina, Stahl explained.

In addition, a slit lamp image of the natural lens shows the patient any lens discoloration.

Widening the appeal of RLE are the Tecnis Symfony IOLs (Abbott Medical Optics), a new extended depth of focus class of IOLs. The single-piece premium lens, approved by the FDA in July 2016, “does not split the light as much as it extends the depth,” Stahl said. “The lens still allows for a distance focus; however, the near working distance is not as close as a multifocal. It is further out; therefore, it is much more functional for our daily living.”

Also, there are fewer halos and less decrease in image quality due to not splitting the light. “You should have fewer postoperative visual complaints with Symfony compared to a multifocal,” Stahl said. Moreover, the FDA approved both spherical and toric versions of the lens.

Stahl’s number of RLE cases has risen dramatically over the past decade, from about 5% to 40% of his overall refractive practice. Outcomes from the procedure are “outstanding,” he said. “You truly have to be a refractive surgeon to be successful. The surgeon has to concentrate on choosing appropriate, healthy patients with realistic expectations. But then you have to hit the refractive target to optimize the patient’s visual outcome.”

Stahl predicted that RLE will continue to grow as a viable option for patients as diagnostic capabilities and IOL techniques continue to advance.

Back to LASIK

The learning curve for LASIK today is “fairly straightforward because all the manufacturers do a good job of training,” according to Durrie. “Introducing new lasers is also fairly standard.”

Durrie observed that the era of having another practice handle patient follow-up is coming to a close.

“I think that a lot of practices are heading in the direction that we are, following their own patients and ensuring they attain the best results, and educating them on the milestones of vision development,” he said. “I believe this is a key to success.”

The two Patient-Reported Outcomes with LASIK (PROWL) studies published in JAMA Ophthalmology are also extremely important because of the way they were designed, sponsored and reported, according to Durrie.

“These studies were not conducted by industry; they were government sponsored by the FDA and the National Eye Institute,” Durrie said.

The goal of both studies was to develop and validate an online patient questionnaire covering preop and post-op criteria.

PROWL-1 was a 6-month study consisting of Navy patients, whereas PROWL-2 was a 3-month study done in private practice, including Durrie’s own practice.

“The results showed that overall patient-reported outcomes for dryness improved and that there were significant improvements in night vision problems, halo and glare after surgery than before,” Durrie said.

Nonetheless, a small group of study patients with no symptoms preoperatively developed mild symptoms at the 1- and 3-month visits.

“Long-term studies show, however, that these symptoms decrease over time,” Durrie said. – by Bob Kronemyer

• References:
• El-Massry A, et al. European Ophthalmic Review. 2015;doi:10.17925/EOR.2015.09.01.17.
• Eydelman M, et al. JAMA Ophthalmol. 2016;doi:10.1001/jamaophthalmol.2016.4587.
• Fernandez J, et al. J Refract Surg. 2016;doi:10.3928/1081597X-20160816-02.
• Igras E, et al. J Refract Surg. 2016;doi:10.3928/1081597X-20160317-01.
• Lee J, et al. Clin Exp Ophthalmol. 2016;doi:10.1111/ceo.12691.
• O’Brart. J Optom. 2014;doi:10.1016/j.optom.2013.12.001.
• Parkhurst GD. Clin Ophthalmol. 2016;doi:10.2147/OPTH.S106120.
• Parkhurst GD, et al. J Refract Surg. 2015;doi:10.3928/1081597X-20150224-05.
• Whitman J, et al. J Refract Surg. 2016;doi:10.1016/j.jcrs.2016.04.024.

• For more information:
• Daniel S. Durrie, MD, can be reached at Durrie Vision, 5520 College Blvd., Suite 201, Overland Park, KS 66211; email: ddurrie@durrievision.com.
• Gregory D. Parkhurst, MD, can be reached at Parkhurst NuVision, 9725 Datapoint Drive, Suite 200, San Antonio, TX 78229; email: gregory.parkhurst@gmail.com.
• R. Luke Rebenitsch, MD, can be reached at ClearSight Center, 7101 NW Expressway, Suite 335, Oklahoma City, OK 73132; email: lrebenitsch@gmail.com.
• Jason E. Stahl, MD, can be reached at Durrie Vision, 5520 College Blvd., Suite 201, Overland Park, KS 66211; email: jstahl@durrievision.com.
• William B. Trattler, MD, can be reached at Baptist Medical Arts Building, 8940 N. Kendall Drive, Suite 400-E, Miami, FL 33176; email: wtrattler@gmail.com.

Disclosures: All sources in this article are members of the Refractive Surgery Alliance. Durrie reports he is a consultant to Abbott Medical Optics and a co-investigator for Alcon. Parkhurst reports he is a consultant to STAAR Surgical, Carl Zeiss AG, Abbott Medical Optics and Alcon. Rebenitsch reports he has received speaking honoraria from STAAR Surgical, AcuFocus and Ziemer, and is a trainer and participates in clinical trials for AcuFocus. Stahl reports no relevant financial disclosures. Trattler reports he has a financial interest in the company CXLO and is a consultant to Abbott Medical Optics and Alcon.

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