- New concepts in refractive surgery
- MIGS overview
- Global perspectives and pearls for refractive surgery
- LASIK flap complications
- Incidence of ectasia after SMILE from a high-volume refractive surgery center in India
New concepts in refractive surgery
Program co-chair of the 2022 AAO Annual Meeting Refractive Surgery Subspecialty Day, Deepinder Dhaliwal, MD, said, that the new age of refractive surgery is upon us. The first session of the day covered everything from virtual consults to understanding optics to treating complex corneas and more.
Neda Shamie, MD, said that the pandemic necessitated virtual consults to maintain patient care, but as things began to normalize, her practice explored how to expand upon virtual consults. She mentioned a study that found patients who had a positive response to telehealth were younger, had minimal medical problems, were highly educated, of a higher socioeconomic class, and more often at the executive/professional level. This is the subclass that represents many refractive surgery patients, Dr. Shamie said.
She went on to detail how her practice has begun performing their initial refractive consult virtually. This consult usually is a meet and greet to establish patient rapport, educate on the different refractive options, and begin discussion of options for the patient based on their submitted refractive history. On average, these virtual consults take 10 minutes and have 55% conversion to surgery rate, compared to 30+ minutes in person and conversion to surgery at 75%. Her practice does about 107 virtual consults per month and is transitioning to technicians performing the entire initial consult.
Julie Schallhorn, MD, presented on matching optics to available technologies. She said that there are a lot of optical strategies that can increase depth of focus. The mainstay strategy, at present, is diffractive optics. She said these options work well, giving both near and distance vision, but they come with some side effects (halo and reduced contrast sensitivity).
Pinhole optics, which has been around for centuries, has an amazing tolerance to positive and negative defocus, Dr. Schallhorn said. The IC-8 Apthera (AcuFocus) is the only IOL with a pinhole optic approved by the FDA. Dr. Schallhorn said pinhole optics are less sensitive to corneal irregularities and increase depth of focus, but because you’re only letting parfocal rays through, you do have a decrease in contrast sensitivity.
Aspheric defocus, as available with the AcrySof Vivity IOL (Alcon), functions by focusing peripheral rays for distance and central rays are focused more tightly for near. There is decreased contrast sensitivity with this technique, Dr. Schallhorn said, as with all IOLs that have spherical aberrations.
“Knowing the behavior of the optical solutions that we have … their tolerance and what they need to work well is critical for giving your patients the best outcome,” Dr. Schallhorn said.
Many patients seeking refractive surgery call the practice asking specifically for LASIK, Gregory Parkhurst, MD, said, and this is where he thinks patient education should begin.
“Is LASIK what the patient really wants in the first place?” he asked, adding later that he’s learned patient aren’t seeking specific, branded procedures. “They just want to wake up and see, and they want the doctor to tell them how to do that.”
There are eight different refractive surgery procedures, and Dr. Parkhurst said it’s important to understand where lens-based refractive surgery fits in that spectrum. If a patient is a good candidate for a lens-based procedure when they’re seeking refractive surgery, Dr. Parkhurst said he floats the concept and waits for the patient’s response. Often, a lens-based procedure is a new concept to the patient, and some need time to consider it.
Saama Sabeti, MD, gave her five pearls for SMILE, learned from her early experience with the procedure.
Pearl 1: Use lenticule anatomy to your benefit. Dr. Sabeti said it’s important for the surgeon to know that certain parameters are adjustable, and others are fixed by the laser platform. Know what is adjustable and use that to your benefit, she said, noting that you can increase the minimal lenticule thickness for lower myopic treatments, which otherwise might be difficult to dissect.
Pearl 2: Don’t forget about cylinder and centration. Dr. Sabeti said the current laser platform does not have cyclotorsion control (though a newer version will). Centration, she continued, needs to be addressed by surgeon and patient effort.
Pearl 3: Mentally prepare your patient. Before entering the OR, Dr. Sabeti advised sitting with the patient and explaining what they should expect, how they need to lay still and keep looking at the green light and continuing to fixate in that direction even when the light goes blurry or disappears.
Pearl 4: Mind your planes, and always check your lenticule. Dr. Sabeti said to dissect the anterior plane before the posterior plane.
Pearl 5: Respect your incision. Dr. Sabeti said to start with a larger incision in your early cases and to use it as a fulcrum for spatula movement.
Extra pearl: Try to take a course with a wet lab component for practice.
Editors’ note: Dr. Parkhurst has financial interests with STAAR Surgical. Dr. Shamie, Dr. Schallhorn, and Dr. Sabeti have no financial interests related to their comments.
MIGS overview
It wouldn’t be Glaucoma Subspecialty Day without a section on MIGS. Thomas Samuelson, MD, led the session, giving a brief history.
He said he felt privileged that his career “spanned this transformation that has radically changed our field.” Dr. Samuelson described how he performed extracaps while in residency and fellowship and transitioned to phaco when he entered practice. He also experienced what he called the “golden era of trabeculectomy;” the procedure, he said, was the darling of the glaucoma community in the 90s. Several things from there “changed and affected everything,” Dr. Samuelson said.
These things were phaco going clear corneal, latanoprost being approved, spurring a pharmaceutical renaissance in glaucoma, and more awareness of the hazards of filtration surgery. Glaucoma procedures morphed into non-penetrating, which then became MIGS, Dr. Samuelson said, while drugs and laser options improved as well.
Overall, Dr. Samuelson said no matter what we do, there is risk. “If we undertreat disease … we let disease risk increase. If we’re too aggressive, we subject patients to unnecessary surgical risk,” he said, adding that it is essential to recognize bad disease when you see it.
Brian Flowers, MD, gave an overview of stenting options for Schlemm’s canal, including iStent inject W (Glaukos) and Hydrus Microstent (Ivantis), which are approved in combination with cataract surgery, and iStent infinite (Glaukos), which is approved as a standalone procedure as of August 2022.
There are some universal pearls for these devices, Dr. Flowers said, such as safety first—the patient should have the equivalent experience to cataract surgery alone, he said. It should have maximum efficacy with the proper techniques being used to achieve the results that mirror the clinical trials. Positioning in an en face view with proper microscope and patient tilt, and the proper magnification and a clear corneal incision should be used. Hydrus requires an incision, separate from the cataract incision, 3–4 hours from the intended implantation site.
Ze Zhang, MD, spoke about trabeculotomy and goniotomy procedures. These work best for patients with targets around the mid-teens, she said. For success, angle landmarks should be identified with gonioscopy preop, the patient should have the ability to remain still for the procedure, and they should have the appropriate expectations set for hyphema and visual recovery. Intraoperatively, patient position should be ideal with visualization under the proper illumination and magnification and with cohesive viscoelastic and trypan blue (or a reflux of blood) for identifying landmarks. Dr. Zhang said to avoid limbal vessels during wound construction.
Vikas Chopra, MD, described subconjunctival MIGS, which are standalone procedures and typically have more robust IOP reduction than non-bleb-forming MIGS. PreserFlo Microshunt (Santen) is not available in the U.S., while the XEN Gel Stent (Allergan) is. The XEN, in a metanalysis was found to reduce pressure about 35% from baseline, on average. Dr. Chopra also explained how XEN has gone through an evolution in terms of the procedure, from ab interno closed technique to ab interno open conjunctiva to ab externo open conjunctiva (off label) and ab externo closed conjunctiva.
Editors’ note: Dr. Samuelson and Dr. Flowers have financial interests with various ophthalmic companies. Dr. Zhang has financial interest with Aerie Pharmaceuticals. Dr. Chopra has no financial interests related to his comments.
Global perspectives and pearls for refractive surgery
This session brought together international speakers to offer their pearls for refractive surgery.
Shizuka Koh, MD, gave her tips on refractive surgery screening. Fourier analysis of corneal power, for example, can quantify irregular corneal astigmatism, and anterior segment OCT showing asymmetry from the posterior corneal surface is useful to discriminate abnormal keratoconus eyes from normal eyes, she said. Dr. Koh said she uses corneal biomechanical assessments because these changes can occur before corneal curvature changes. In addition, she noted the utility of objective, multimodal imaging as helpful in borderline cases, and said a family history of keratoconus should not be ignored.
Ashiyana Nariani, MD, provided her top pearls for LASIK. 1) Utilize LASIK to address the global burden of refractive error. She said that glasses are not permanent, and refractive surgery is being considered a tool to cure refractive error-related blindness and visual impairment. 2) Improve outcomes using technology to your advantage. Artificial intelligence, for example, can help determine the ideal procedure choice for a patient. 3) Optimize the ocular surface prior to LASIK. Dr. Nariani said that it’s well known OSD impacts visual acuity, refraction, topography, and patient comfort after LASIK. 4) Don’t wet the bed too much. Avoid tools that can risk over irrigation, which can cause the LASIK flap to swell or underswell asymmetrically. 5) LASIK surgery ends at the slit lamp. Dr. Nariani said to build in time at the slight lamp right after the procedure to identify and iron out microfolds, detect corneal foreign bodies in the flap interface, and confirm flap centration.
Additional pearls for advanced surface ablation were presented by Marcelo Netto, MD, PhD. Dr. Netto first reiterated the importance of ocular surface analysis and optimization, especially because it affects corneal wound healing for surface ablation. Next, he said to be cautious about offering PRK to a patient when they are not a candidate for LASIK. Intraoperatively, Dr. Netto said to know the concentrations and application times for using MMC to prevent corneal haze. He also discussed minimizing corneal toxicity and postop care.
As a final pearl offered in a short panel discussion, Marguerite McDonald, MD, pointed out that the ablation rate changes very quickly once the epithelium comes off.
“Once the epithelium is off, you’ve got to move if you want really good outcomes,” Dr. McDonald said.
Editors’ note: Dr. Koh has financial interests related to her comments. Dr. Nariani and Dr. Netto have no financial interests related to their comments.
LASIK flap complications
During a session at Refractive Surgery Subspecialty Day, J. Bradley Randleman, MD, discussed some LASIK flap complications that can occur. He noted that these may be flap dislocations or flap disruptions.
He shared a case of a patient who had been hit in the eye, and it was managed conservatively as a corneal abrasion. The flap edge had been hit, and Dr. Randleman noted an OCT image showed that the flap was rolled upon itself.
This can be a bit of a challenging repair, he said, adding that the first thing you want to do is get the flap nicely elevated and take care not to damage the tissue.
He delicately took the tissue off, and said, when dealing with an issue like this, to make sure there are no other holes or tears in the flap. These might not be immediately evident, he said.
He needed to unfurl the flap edge to help make sure to reduce the chance of having epithelial ingrowth at the end. He noted that it can be helpful to take the epithelium off all the way at the limbus, which he said will give a head start for the flap to heal down.
There are many ways to do the work on the flap itself, Dr. Randleman said, adding that “it is a bit tedious.”
In his case, Dr. Randleman worked on getting the flap edge unfurled. He noted that, if possible, you want to try to reorient the flap anatomy as it was ahead of time. If that’s challenging, he said, you’d rather lose a bit of a flap edge rather than leave the folded flap because that could incite flap ingrowth. “If you lose a little bit of the edge, it’s not the end of the world,” he said.
Since it was this patient’s first repair, Dr. Randleman said he opted not to suture or fixate it, but this is an option, he said. The patient did well postoperatively.
Editors’ note: Dr. Randleman has no related financial interests.
Incidence of ectasia after SMILE from a high-volume refractive surgery center in India
Sheetal Brar, MD, shared data from her study, with the purpose to report the overall incidence of ectasia after SMILE from a high-volume tertiary refractive surgery center in India and to compare the incidence of ectasia in eyes undergoing SMILE and SMILE Xtra (SMILE combined with simultaneous accelerated crosslinking).
Postoperative ectasia remains one of the most significant complications of corneal refractive surgeries, Dr. Brar said. Incidence studies, she said, are needed to understand the magnitude of the problem, to assess the correlation of associated risk factors, and to take preventive actions.
The study was a retrospective study where all eyes operated for SMILE/SMILE Xtra for myopia or myopic astigmatism from November 2012–August 2019 were reviewed for topography and treatment planning and reanalyzed.
The study included 7,024 eyes operated during that period, and 10 of the eyes had ectasia (0.15%). When split further into groups of normal eyes (SMILE), borderline eyes (SMILE), and borderline eyes (SMILE Xtra), Dr. Brar said the study found 2 of 6,025 eyes in the normal eye group to have ectasia (0.03%); 8 of the 594 eyes in the borderline SMILE eyes had ectasia (1.3%); and none of the 405 eyes in the borderline SMILE Xtra group had ectasia. She added that, when looking at the individual instances of ectasia, it was found that a number of these eyes had other risk factors as well.
This was the first study reporting incidence of post-SMILE ectasia, involving 7,000 plus eyes, over a 7-year period, she said. The incidence of ectasia following SMILE (0.15%) was comparable to that reported after LASIK (0.02%–0.6%) in various studies, Dr. Brar added. She added that more data and long-term studies are required to derive the incidence, due to different practice patterns and guidelines followed.
Editors’ note: Dr. Brar has financial interests with Carl Zeiss Meditec.
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