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Overcoming the PRK mindset: Incorporating LASIK, SMILE into the military
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The reason for undergoing refractive surgery as a member of the U.S. military is not necessarily a medical one.
For this population, wearing glasses in combat would encumber aiming systems, helmets and faceguards. In many cases, glasses and contacts are an unsafe option for soldiers deployed to harsh or combat environments, Gregory D. Parkhurst, MD, FACS, said.
“For that reason, refractive surgery is considered to be an important program for line officers and their troops, not only from the perspective of being more likely to accomplish their mission, but also in terms of their own personal safety,” Parkhurst said.
Parkhurst is president of the Refractive Surgery Alliance and served as an Army major until 2011, during which time he underwent PRK himself. He trained at Walter Reed Army Medical Center.
Image: Villarreal A
“When you’re in the military, you’re concerned with your personal safety, but also the safety of the soldiers around you. If your glasses get knocked off while you’re knocking down a door, not only are you putting yourself at risk, but potentially your compatriots as well. You have to do a specific job, so if you can’t see, you’re potentially putting your whole unit at risk in the heat of the battle.”
Within the Department of Defense, spectacle-free vision is seen as a means for preparing for battle, “not so much a medical need or medical condition,” Parkhurst said. As such, the DoD refractive surgery program is funded via a military warfighting budget that is separate from the department’s medical program, Parkhurst said.
PRK, LASIK, SMILE
The military approach to refractive surgery basically comes down to LASIK, PRK or SMILE, according to OSN Refractive Surgery Section Editor John P. Berdahl, MD. All three procedures provide visual acuity that meets DoD requirements. Parkhurst noted that phakic IOLs are also common in patients who are not candidates for laser vision correction.
PRK has a long track record of success as a vehicle for delivering spectacle-free vision for armed forces personnel who deploy into conditions where glasses or contact lenses would be a handicap. In 1995, PRK was the first vision correction surgery using a laser to be approved by the FDA; subsequently, it was also the first refractive surgery procedure allowed to be performed in members of the military when the DoD adopted laser refractive surgery in 2000.
LASIK, approved by the FDA in 1998, has been variably adopted into branches of service for specified populations since the mid to late 2000s.
Small incision lenticule extraction, or SMILE, (Carl Zeiss Meditec) is a recent addition to the military’s refractive surgery tool box. Cmdr. John B. Cason, MD, head ophthalmologist at Naval Medical Center San Diego’s Navy Refractive Surgery Center, performed the first four SMILE procedures done at a Navy medical facility in April. SMILE was approved by the FDA in September 2016.
PRK persists as preferred option
Even though LASIK and SMILE are both acceptable procedures in certain settings for members of the military, PRK persists as the predominant procedure, perhaps simply because it is embedded in military culture.
Each option presents benefits, so it is up to the ophthalmologist to discuss the advantages and drawbacks of each refractive surgery procedure to help a patient determine which is best, Cason said.
The drawback for PRK is that it results in much longer visual recovery time and greater discomfort. Regardless, members of the military often request to have PRK over other refractive surgeries because they have seen the good results in friends who have undergone the procedure, Steven C. Schallhorn, MD, said.
LASIK has long been stigmatized in military circles because of the perceived risk of flap dislocation that could occur with trauma. That stigma is difficult to get past, according to a presentation by Scott D. Barnes, MD, given at Hawaiian Eye 2017.
The development of the femtosecond laser was a game changer for LASIK, Barnes said in the presentation. The key to the procedure is the 120° inverted side cut vs. the 90° cut. It has been shown and published to have increased strength compared with a microkeratome and a temporal-based hinge, according to Barnes.
SMILE is a “nice hybrid procedure of PRK and LASIK,” Cason said, with a favorable recovery that is typically several days quicker than PRK recovery. SMILE incorporates use of a femtosecond laser to correct refractive error by creating a corneal lenticule and extracting it through a small incision without the use of an excimer laser.
But SMILE is a new procedure to the military, and Cason said that PRK is still the most popular refractive surgery procedure performed in active military members. He estimated that about 75% of refractive surgery procedures performed in DoD personnel are PRK.
LASIK
According to Schallhorn, lingering concerns about the stability of the LASIK flap when studied are “mostly unjustified.”
Schallhorn, a veteran of the Navy for more than 30 years until his retirement in 2007, is the founder of the Department of Defense refractive surgery program. He predicts PRK will slowly lose ground to both LASIK and SMILE in terms of popularity among active military members.
“LASIK and PRK are both excellent procedures. But there are significant differences in visual recovery, with LASIK being much quicker. On many levels faster visual recovery is beneficial, such as quicker return to work,” Schallhorn said.
Berdahl said that his “general tendency” when operating on military personnel is to lean toward LASIK.
“But I will reach out to a commanding officer [and the soldier] to make sure that what we’re doing is not going to preclude them from appropriate advancement in the military,” Berdahl said. “It’s not standard protocol, but I want to make sure that I’m not limiting that soldier’s progression and so I double check to make sure there are no issues.”
In a civilian setting, Berdahl said the two most common refractive surgery procedures he performs are wavefront-guided and wavefront-optimized treatments. His current approach is to use more wavefront-optimized treatments for higher corrections, such as higher myopia, hyperopia and astigmatism, and to use wavefront-guided treatments for lower myopes and younger patients.
“The reason for that is we generally don’t want to include wavefront information that may be in the lens of an older patient into the treatment of their cornea. We don’t want to punish the cornea for the sins of the lens,” he said.
In the military, however, “With such a youthful surgical population, the worries of wavefront-guided procedures do not apply,” he said.
SMILE
The SMILE procedure has even more appeal for members of the military despite the continuing popularity of PRK, according to Schallhorn.
The SMILE procedure “combines the advantages of PRK, meaning there is no flap to create or displace, and yet has visual recovery more similar to LASIK,” Schallhorn said.
Faster visual recovery translates to faster return to active duty, according to Parkhurst.
“We would put soldiers back to full-duty readiness 6 weeks after LASIK, whereas we wouldn’t allow them to be at full duty or deployable readiness for 3 months after PRK. With SMILE, I think we’re going to get the patients ready quicker again. The speed in return to visual recovery also comes with the long-term advantage of not having a flap on the cornea, which is applicable to the military population that may be exposed to facial trauma. It combines the benefits of LASIK with the benefits of PRK. I think that will become an important surgery in the military refractive surgeon’s tool box,” he said.
About 15% to 20% of military personnel contemplating refractive surgery are potential candidates for SMILE, Cason said.
“Right now it’s just for spherical myopia. I would say there’s not a large percentage of our patients who qualify, but still there are 15% to 20% of patients who are potential candidates. A lot of those people are interested in the procedure in part because it’s new, in part because you don’t have a flap like you do with LASIK, but at the same time you don’t have the extended recovery as you do with PRK. It’s a great third option. It’s a great extra procedure to have in your tool kit to meet the needs of the patient,” Cason said.
“So far, we’ve treated about 15 patients in the last month, and they’re all doing very well. We’ve treated everything from a –2 D to a –9 D, and all of them have been very happy with their vision. I’d say their postoperative day 1 visual acuity was very similar to LASIK. As a matter of fact, most patients were seeing 20/20 or better. A couple of eyes were 20/25, but that’s not very different from our typical LASIK outcomes either. By the 1 week postoperative mark, they typically pick up another line of vision as well,” Cason said.
At the 2017 American Society of Cataract and Refractive Surgery annual meeting in Los Angeles, Mark F. Torres, MD, presented the results of his study that noted SMILE has the potential for minimal disruption to the ocular surface and less energy delivered to corneal tissue, which means it may offer more benefits to the Department of Defense than the gold standard of surface ablation.
Torres noted at the meeting that SMILE preserves the nerve supply in the eye everywhere except the side cut, which may be important in minimizing dry eye symptoms. For military members who are in arid environments, any potential reduction of dry eye symptoms could be an advantage, Berdahl said.
“SMILE is a new option, and we don’t have to worry about flap dislocation. There’s a possibility you get some of the benefits of quicker recovery that come along with LASIK with no risk of flap dislocation and potentially some advantages because some folks are in arid environments where dryness may be an issue. It’s possible that SMILE may have some advantages in relation to dryness,” he said.
Military leads the way
The highly successful DoD refractive surgery program has served the members of the military very well since its establishment, Schallhorn said.
“Refractive surgery in the U.S. military is an established program that provides an enormous benefit to those that serve. Offering procedures that can safely and effectively reduce dependence on glasses or contact lenses to military members not only enhances their job performance and mission effectiveness but also improves the quality of their life. This has been made abundantly clear over the years. Everyone I know who has served in the military fully understands and appreciates the reason DoD provides refractive surgery,” Schallhorn said.
Berdahl stressed the importance of the refractive surgery program and all it does to keep active members of the military safe. The program contributes a great deal of science and research to the field of ophthalmology, so it has a further-reaching effect than just the armed forces, he noted.
“We owe a big debt of gratitude to the military, not only for the service they provide, but also for the science they provide. They do some of the best studies on refractive surgery. It removes a lot of the economics, just looking at what makes patients the most functional. We in ophthalmology all owe a big debt of gratitude on a number of fronts to our military brothers and sisters who take care of soldiers,” he said.
It is important for the refractive surgery program to continue to independently and objectively evaluate the latest technologies that can enhance a service member’s ability to conduct his or her job more safely and effectively, David J. Tanzer, MD, said.
Tanzer, who retired from the Navy in 2011, said the refractive surgery research programs have “carried out rigorous testing of various procedures for over 20 years” and have proven that modern refractive surgical techniques result in a more effective fighting force. Since its inception, the program has conducted more than 750,000 refractive procedures in the military.
“The rigorous safety and efficacy evaluation that has been undertaken by the U.S. military toward refractive surgery has direct implications on the civilian population. Whether it is a first responder, such as a paramedic, firefighter or police officer, or anyone in a potential survival situation, or even an active sports enthusiast, all will benefit in those activities and environments without a need for corrective lenses. Acknowledging that no surgical procedure is without risk, over 9,000 publications worldwide, stemming from thousands of well-conducted studies, continue to demonstrate that refractive surgery is the safest and most effective elective procedure that exists and one that generates the highest levels of patient satisfaction,” he said.
New procedures are continually being assessed, improved and developed by the research programs in the military, Tanzer said.
“As lasers continue to improve in how they ablate corneal tissue, such as wavefront guided, topography guided, optimized and various combinations thereof, and where in the cornea they have their effect, such as the surface, under a lamellar flap or lenticular extraction, rigorous safety and effectiveness evaluation will continue to be performed by the research programs in the military, ensuring that these technologies deliver on the promise that comes from industry and that these procedures are appropriate for the modern warfighter and the unique environments in which they work,” he said.
Overcoming barriers
The military’s refractive surgery program has helped overcome barriers to adoption in the civilian population. Due to rigorous testing, presenting and publishing of results, the military has been able to diminish fear of certain complications that may stem from refractive surgery procedures, Tanzer said.
NASA approved the use of refractive surgery for astronauts a decade ago based on the safety and efficacy demonstrated through independent studies by the military, “emphasizing improved functional vision in austere environments,” he said.
“With absolutely no industry-based financial incentive for such approvals, the civilian population contemplating refractive surgery can make rational decisions based on facts and data demonstrating overwhelming safety and efficacy, rather than being distracted by anecdote and hyperbole that is oftentimes propagated through social media, which seeks to denigrate the reputation of modern refractive surgery. I am honored to have been a part of the rich legacy of refractive surgery research in the U.S. military and take pride in the accomplishments of the current programs which continue the important work of independent verification and validation of the safety and efficacy of modern refractive surgery,” he said. – by Robert Linnehan
- References:
- Barnes SD. The unique difficulty of reintroducing LASIK in a surface-friendly world: Is LASIK really better than PRK? Presented at: Hawaiian Eye; Jan. 14-20, 2017; Koloa, Hawaii.
- Naval Medical Center San Diego performs first refractive surgery of its kind in the Navy. http://www.navy.mil/submit/display.asp?story_id=99779. Published April 7, 2017. Accessed May 15, 2017.
- Sia RK, et al. J Refract Surg. 2014;doi:10.3928/1081597X-20140320-04.
- Tanzer DJ. What laser vision correction means to the military. Presented at: FDA Ophthalmic Devices Panel hearing; April 2008.
- Torres MF. Update on small incision lenticule extraction (SMILE). Presented at: American Society of Cataract and Refractive Surgery annual meeting; May 5-9, 2017; Los Angeles.
- For more information:
- John P. Berdahl, MD, can be reached at Vance Thompson Vision, 3101 W. 57th St., Sioux Falls, SD 57108; email: john.berdahl@vancethompsonvision.com.
- Cmdr. John B. Cason, MD, can be reached at Naval Medical Center San Diego, 34800 Bob Wilson Drive, San Diego, CA 92134; email: john.b.cason.mil@mail.mil.
- Gregory D. Parkhurst, MD, FACS, can be reached at Parkhurst NuVision, 9725 Datapoint Drive, Suite 200, San Antonio, TX 78229; email: gparkhurst@parkhurstnuvision.com.
- Steven C. Schallhorn, MD, can be reached at Gordon Schanzlin New Vision Institute, 8910 University Center Lane, Suite 800, San Diego, CA 92122; email: scschallhorn@yahoo.com.
- David J. Tanzer, MD, can be reached at email: djtanzermd@yahoo.com.
Disclosures: Berdahl reports he is a consultant for AMO, Alcon and Carl Zeiss Meditec. Cason reports his views are his own and do not necessarily reflect the official policy or position of the Department of the Navy, the Department of Defense or the U.S. government. Parkhurst reports he is a consultant for Carl Zeiss Meditec, STAAR Surgical, Alcon and Johnson & Johnson. Schallhorn reports he is the chief medical officer of Carl Zeiss Meditec. Tanzer reports no relevant financial disclosures.
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