- New refractive topics in 2023
- Basics of refractive surgery
- New ideas in glaucoma
- How clinical trials have shaped refractive surgical experience
New refractive topics in 2023
Farhad Hafezi, MD, PhD, presented on an option for doing crosslinking at the slit lamp. Shifting to this approach, he said, is moving to an infrastructure that is much less heavy in terms of what is necessary to do crosslinking. It can prove beneficial because in many areas of the world, there is not steady access to operating rooms. So it’s important to find a way to perform crosslinking in a safe way for large populations. This option, he said, could help democratize access to crosslinking. It also could potentially reduce costs in all areas, as doing office-based procedures would heavily reduce costs.
Dr. Hafezi described the C-eye device, which can be mounted on the slit lamp, to allow for this procedure to be as versatile as possible.
He described the process of how to do crosslinking with this approach. First, apply anesthesia. Then, mount the machine, and Dr. Hafezi noted that it fits all major slit lamps. Use a speculum and perform the debridement and removal of the epithelium. The patient is seated in a reclining chair to do ultrasound to check the stromal thickness and for riboflavin application, then goes back to the slit lamp for ultraviolet irradiation.
In his presentation, Francesco Carones, MD, discussed a new presbyopia IOL, the Tecnis PureSee (Johnson & Johnson Vision), which he described as a purely refractive EDOF IOL. However, he noted that it’s not approved yet. This IOL is based on proprietary refractive technology that enables continuous changes in power; it distributes the light from far to near with a monofocal-like dysphotopsia profile.
The anterior optic has an identical aspheric surface, designed to compensate for the spherical aberrations of the cornea, which Dr. Carones said is equivalent to any Tecnis IOL (Johnson & Johnson Vision). The posterior optic has a posterior refractive surface with a modified refractive design that maintains a dysphotopsia profile comparable to a monofocal IOL, enables a consistent depth of focus extension from distance to near, and maintains excellent distance vision (not only at best focus but also increases tolerance to refractive errors).
Patients have been so far pleased with results, he said. Preliminary results have shown a broad range of vision with the appearance and quality of vision comparable to a monofocal, Dr. Carones again stressed. Results have also shown spectacle independence with limited/neglectable compromises, with consistent and predictable outcomes.
Editors’ note: Dr. Hafezi has financial interests with several ophthalmic companies. Dr. Carones has financial interests with Johnson & Johnson Vision.
Basics of refractive surgery
A refractive session highlighted various procedures and technologies. Julie Schallhorn, MD, shared information about trifocal IOLs and different options available. To understand differences in trifocal IOLs, you first have to understand how they work, she said. These work with diffraction, the bending of a wave around an object into a region of geometric shadow. Trifocal lenses use a blazed grating, which is a circular pattern of triangles etched under the surface of the IOL. She added that trifocal IOLs are actually quadrifocal, with two distance focal points, one intermediate and one near.
Dr. Schallhorn went on to discuss pupil diameter and light distribution. We can make different light distributions depending on different pupillary diameters, she said. For example, the FineVision trifocal (Bausch + Lomb) devotes more light to distance focal points as the pupil gets bigger, and as the pupil gets smaller, more light goes to intermediate and near points. The Zeiss AT Elana has similar distribution to all ranges, while the Alcon PanOptix has constant light distribution with lower pupil diameters, but once you get higher diameters, there is more light to distance points. Ring spacing also affects light distribution.
Is apodized or non-apodized better? Dr. Schallhorn said it’s tough to know because pupil response may not always match vision demands. Intermediate and near distance depend on lens design in these lenses.
She also highlighted photic phenomena that may occur with trifocal lenses, like diffractive streaking. However, she noted that there currently is no data to compare photic phenomena among different trifocal lenses. There is, however, an effort to develop a questionnaire that would be able to address this. Dr. Schallhorn said that there is evidence that compared to monofocals, trifocal IOLs induce more photic phenomena.
In summary, she said that trifocal IOLs use a diffractive kinoform to achieve multifocality. Light distribution is a property of lens design and can influence acuity. Near and intermediate distances are determined by lens design, and photic phenomena are increased relative to monofocal IOLs for all trifocals.
Editors’ note: Dr. Schallhorn has financial interests with Zeiss.
New ideas in glaucoma
During a session covering new ideas in the glaucoma field, Don Hood, PhD, spoke about whether OCT can predict field loss and when the central field should be tested.
He first discussed when to perform a 10-2 visual field test. The common answer is for eyes with advanced glaucoma. But Dr. Hood said this should be done if you think a glaucoma patient needs a 24-2/30-2 field. They should have a 10-2 as well or instead because the 24-2 or 30-2 test pattern can miss and/or underestimate central/macular damage.
When do you perform an OCT scan of the macula? Dr. Hood again noted the “old answer,” which was only getting OCT scans of the disc. But he said all glaucoma patients should have a scan that includes the macula because central/macular damage is very common, and an OCT disc scan (as typically performed) can miss and/or underestimate damage seen on a cube scan of the macula.
Addressing whether OCT can predict field loss, Dr. Hood said it can. He added that there is agreement between visual fields and OCT as long as you compare local visual field loss to local loss of GCL and/or RNFL.
Also in the session, Sally Baxter, MD, discussed why to participate in glaucoma registries. There are a variety of benefits, she said, including understanding real-world practice patterns and outcomes, increasing sample sizes/statistical power (enhanced rigor and enables study of rare diseases), combining multiple data types, and enhancing diverse representations (for both patients and researchers). She spoke about several available registries, including local/institutional data warehouses, the IRIS Registry, and the All of Us registry. There are several registries that work on a nationwide scope.
Editors’ note: Dr. Hood and Dr. Baxter have financial interests with several ophthalmic companies.
How clinical trials have shaped refractive surgical experience
Vance Thompson, MD, gave a keynote lecture about how clinical trials have shaped his refractive surgical experience. Quality research, when executed properly, can help shape the future of eyecare, he said.
Dr. Thompson’s refractive surgery journey began with his fellowship. His first assignment in 1990 was to travel to San Diego, California, to film one of the early PRK procedures being performed. There was excitement but also a lot to learn. “I had no idea how that trip and fellowship would open up a world of research for me that influenced my career,” he said.
He worked on a clinical trial for PRK, working on legally blind eyes, and he noted that they didn’t even use bandage contact lenses. It was the beginning of an amazing procedure that also included PTK, he said. Later, Dr. Thompson was involved as a principal investigator for LASIK, femto, and SMILE.
One interesting thing Dr. Thompson addressed in refractive surgery was the business side and why people don’t have refractive surgery at the rate physicians might think they should be having it. He mentioned both price and fear as potential factors.
He advised to let the process and well-structured clinical trials play a central role in your thinking versus a gut feeling. It’s important to able to critically appraise the latest research and apply this to current patient care.
Dr. Thompson then shared instances where his gut feeling was wrong, and the research saved him. In 1994, he had the mindset that PRK was king, and LASIK was for high corrections. But later, he saw powerful data on ways that LASIK could be applied.
He also was initially hesitant to get involved as a phakic IOL investigator because he thought refractive surgery was in the cornea. But he became a phakic investigator after being approached by George Waring III, MD, who asked him to reconsider.
Dr. Thompson also mentioned the importance of patient reported outcomes (PROs) and wanting to see more of this. Studies focus on objective measures to evaluate success, he said, but PROs can complement this.
In conclusion, Dr. Thompson said he has learned that research guides evidence-based medicine. It can help advance the profession, and when done right, can be a practice and a career enhancer, he said.
Editors’ note: Dr. Thompson has financial interests with several ophthalmic companies.
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