Friday's "Hot Off the Press" session at the 2024 annual meeting of the American Academy of Ophthalmology showcased innovations in refractive surgery including robotics, small-aperature IOLs, treatment of irregular corneas and the benefits of corneal mapping.

Robert K. Maloney, MD: Robots Come to Ophthalmic Surgery

By now we’ve all heard that robots will soon take over some tasks that have always been performed by humans … but did you know that ophthalmic surgery is one of them? Robert K. Maloney, MD, MA, explained in his presentation on robotic eye surgery for the “Hot off the Press” session that “Ophthalmic surgery can be done by robots in two ways: robot-assisted surgery, in which the surgeon controls the robot using a handpiece or a console; and surgeon-supervised autonomous surgery, in which the robot does part or all of the surgery under AI control, with human oversight.” 

Four companies are currently developing robots for ophthalmic surgery: Aucsurgical, Forsight Robotics, Horizon Surgical Systems and Zeiss Exchange Robotics. These systems are focused on either retina surgery or cataract surgery, which, because it is repetitive and reproducible from patient to patient, is easier to automate than other types of surgery.

Robotic surgery offers a number of advantages over surgery performed by humans, Dr. Maloney said, including:

• Large movements of the surgeon’s hand are demagnified into much smaller movements of the robotic arms. This allows very delicate movements to be done more safely, such as peeling an epiretinal membrane or administering a subretinal injection.
• “No fly zones” of safety can be virtually created around the vital structures in the eye. For example, a robot assisting a cataract surgeon can prevent the surgeon from moving the phaco tip against the endothelium or posterior capsule.
• The robot has a faster reaction time than humans and can pull the instruments out of the eye faster if the patient moves.
• Robots are easier to train than humans.
• One surgeon can guide three robots in three ORs simultaneously, thereby significantly increasing efficiency.

However, Dr. Maloney noted, robotic surgery has disadvantages to work out, including the longer surgical times robots log, the high price tag of robots, and the possible difficulty in training robots to deal with rare events.

Still, “Robots are safer and more precise than human hands for some applications,” said Dr. Maloney. “By the end of the decade, I expect that robots will be performing AI-guided cataract surgery under the supervision of a surgeon.

Elizabeth Yeu, MD: Refractive Surgery and Small-aperture IOLs

While on-label to be utilized as monovision in the nondominant eye for more than a year, we understand that small aperture “can absolutely extend depth of field and depth of focus,” Dr. Yeau said. She added that there’s a smoother, more continuous, seamless broad range of vision, she said, compared with IOLs that may have a single point of light or different multifocal points of light. 

The pivotal trial study design compared groups with a small-aperture IOL in the nondominant eye and monofocal or monofocal toric in the dominant eye with a monofocal IOL group. All subjects had less than or equal to 1.5 D of preoperative corneal astigmatism. One-year follow up showed the small-aperture IOL delivered approximately 2 diopters EDOF over the monofocal IOL and excellent overall quality range of vision. The small-aperture IOL patients achieved equivalent binocular distance and superior intermediate and near vision to patient with bilateral monofocal IOLs. Bilateral contrast sensitivity was non-inferior to the monofocal control group.

“Most importantly, looking at the severity of visual symptoms, the small-aperture IOL patients rated the severity of the symptoms to be very low, or comparable to control lens, with only approximately 3-4% of patients in that small-aperture group reporting experiences of severe glare, haloes or starbursts.

Special considerations in small-aperture IOLs: Pilocarpine 1% can be used in preoperative testing, as it helps simulate range of vision; ray-tracing simulation of small-aperture can be done with different technologies over a 1-2 mm entrance pupil (she generally does a 2-mm pupil); will mask up to 1.5 D of astigmatism in the pivotal clinical trial, and mitigate more; improves peripheral higher-order aberrations to improve quality of vision; however, the pupil must be dilated to at least 6-6.5 mm.

“Where this lens really shines is in these irregular corneas,” Dr. Yeu said. She noted the improvements to vision demonstrated in Nicole Fram, MD’s, work showing that those with irregular corneal astigmatism who start with poor uncorrected distance and near vision “can improve particularly for the distance, with 7 lines of uncorrected distance visual improvement to 20/30+ or so and uncorrected near.”

Eric D. Donnenfeld, MD: Treatment of the Irregular Cornea: Turning Footballs Into Basketballs

Dr. Donnenfeld said that anytime he removes tissue in a patient with ectasia, he likes to start with crosslinking no matter how old the patient is. He likes to do crosslinking first in patients who are having topographic ablations because in pivotal FDA trials he participated in, “We showed that a lot of patients had significant changes in their refractive indexes after surgery, so why treat the patient and then have the patient’s cornea change afterwards?”

He explained that there are basically two schools of thought on crosslinking and excimer laser ablation: Simultaneous and consecutive. But his experience with simultaneous treatment  — meaning one treatment day for more rapid visual rehabilitation, in which the surgeon ablates the tissue first and then crosslinks the deeper tissue — is that it almost always results in more healing problems, more risk of scarring.

Dr. Donnenfeld prefers to perform the treatments consecutively; he nearly always performs crosslinking first, then waits 3 months to perform topographic ablations. The result, he finds, is less likelihood of epithelial healing issues, less risk of corneal haze and scarring, and more accurate topographic ablation.

For mildly irregular corneas, he said the options are topographic or wavefront excimer ablation. Newer wavefront aberrometers that have a lot more data points allow the physician to treat irregular corneas much more effectively, treating not only anterior cornea, but posterior cornea as well.

With a great majority of keratoconic patients, though, he said the physician may not be able to obtain a good aberrometry. “Here topographic ablation is extraordinarily helpful, changing lives. I think we’ve prevented hundreds of corneal transplants, we’ve moved patients from gas permeable lenses to soft lenses,” he said.

Baseline for topographical ablation is a successful image capture. Without it, he explained, you can’t do the treatment.

Regarding patient education, Dr. Donnenfeld stressed that the surgeon should never promise patients that you will eliminate their glasses. Instead, tell them you will improve their visual acuity, as refractive results can be unpredictable.

He also offered guidance for dealing with patients when you cannot obtain a good topographic image and for patients who cannot have a topographic ablation.

“For those of us who do refractive surgery, a lot of times it’s considered cosmetic. This is anything but cosmetic,” he said. “This is visually rehabilitating for some of the most difficult patients we have in our practice. In summary, we crosslink, improve the ocular surface, obtain treatable topographic images, evaluate the treatment pattern and make sure it compares it to the topography. Then adjust treatment diameter and refractive error based on pachymetry, give the patient informed consent on visual goals.”

Vance Thompson, MD: Corneal Epithelial Mapping

In his presentation on “Corneal epithelial mapping in refractive surgery,” Vance Thompson, MD, made the case that it is an invaluable tool to refractive and cataract surgeons, likening it to sonar, showing what “lies beneath the waves” before surgery.

It is thanks to the work of Dan Reinstein, MD, and colleagues, he noted, that we know what a normal cornea map looks like —5.7 µm thicker inferiorly than superiorly and 1.2 µm thicker nasally than temporally with a mean central thickness of 53.4 µm, as measured with very high frequency digital ultrasound. Reinstein et al’s 2008 study gave ophthalmologists a baseline. Dr. Thompson pointed out that we also know that the corneal epithelium accounts for 10% of total corneal thickness and that, importantly, it is capable of remodeling to account for focal change in curvature or stromal irregularity — that it can compensate to stromal changes, he said, masking irregularities. 

Epithelial thickness mapping was approved by FDA in 2017, and continuing innovation has enabled even more accurate mapping with the development of anterior segment OCT, Dr. Thompson said. Clinical applications, he noted, include:

• Keratoconus detection, where epithelial mapping can confirm that subtle topographic changes really are abnormal.
• Refractive surgery — where it helps with screening, decision-making and postsurgical analysis;
• Subclinical anterior basement membrane dystrophy, and;
• Cataract surgery, both pre-and post-care.

Additionally, Dr. Thompson detailed “distinctly different enhancement situations where epithelial mapping can help you make the right decision”: Pre or post cataract surgery with an advanced implant (the patient’s cornea never had surgery) where the epithelium may be the source of reduced image quality; and post corneal refractive surgery seeking enhancement.

“Much like sonar can help an ocean ship navigate potentially dangerous water that looks smooth on the surface but is covering rocky elevations, epithelial mapping can help the refractive and cataract surgeon see potentially dangerous corneal stromal elevations where epithelium has thinned and depressions where epithelium has thickened and uncover what a normal topography could not,” Dr. Thompson said.