A Clear View
THE LATEST TECHNOLOGIES AND PROCEDURES HELP SHARPEN WARFIGHTERS’ VISION.
The U.S. Department of Defense understands the importance of a warfighter’s eyesight. Even with the proliferation of C4ISR sensors and other technologies on the 21st-century battlefield, eyesight remains the instrument that may ultimately allow the marksman, pilot, mariner and other combatants to dominate the battlespace.
Recognizing the importance of the service men and women’s vision, the services conduct surgical procedures to reduce the dependence of its airmen, sailors, soldiers and Marines on spectacles and contact lenses. These successful surgeries have enabled the servicemember to be more effective on the job and enjoy an improved quality of life off-duty.
TYPES OF SURGERIES
Corneal refractive surgery (CRS) is a procedure designed to reduce an individual’s dependence on eye glasses and/or contact lenses. CRS uses a laser to remove (ablate) a thin layer of the clear tissue on the front of the eye, the cornea. The amount of tissue ablated is precisely controlled. The result is a reshaping of the cornea and thereby a change in a patient’s refractive correction. The Food and Drug Administration (FDA)-approved CRS procedures used by the Services fall under two broad areas, advanced surface ablation and intra-stromal ablation.
“Advanced surface ablation uses an excimer laser to reshape the cornea to correct vision,” explained Lieutenant Colonel Charles Reilly, consultant to the U.S. Air Force Surgeon General for Refractive Surgery. Photorefractive Keratectomy (PRK), Epi-LASIK (Laser-in-Situ-Keratomileusis) and Laser Epithelial Keratomileusis (LASEK) are examples of advanced surface ablation.
These procedures should not be confused with LASIK surgery, the subject of a proliferation of commercials throughout the electronic and print media. “LASIK differs from advanced surface ablation in that a flap is created in the cornea and the flap lifted; then the excimer laser energy is applied to reshape the cornea to correct the vision and the flap replaced,” added Reilly. One data point on the increasing demand for these procedures can be gleaned from the Navy, which reports that more than 15,000 procedures are performed annually at its seven refractive surgery (RS) centers.
For its part, the Air Force states that refractive surgery is the most successful elective-surgery procedure ever conducted, with over 48,000 surgical procedures having been performed. The Air Force’s five RSs report that over 93 percent of patients have 20/20 vision, or better, without any glasses after their surgery. While the effectiveness of these procedures is bolstered by the technologies described later, at the end of the day, the success of these procedures resides with the patient.
“The physical constraint that adds variability to the surgery results, is the individual’s healing property,” pointed out Commander David J. Tanzer, Navy Bureau of Medicine and Surgery, Refractive Surgery Program Manager.
ELIGIBILITY
Advanced surface ablation and intrastromal ablation procedures are authorized for all USAF personnel.
All active component Navy and Marine Corps personnel with 12 months of obligated time on their present enlistment or remaining commissioned service are eligible for a screening consultation for CRS and LASIK surgery. Similarly, reserve component personnel from the two services must have 12 months of obligated service remaining on their current recallto- active duty orders to be screen eligible.
The U.S. Army Warfighter Refractive Eye Surgery Program (WRESP) is a mission-readiness program open to all active duty Army personnel, “with at least 18 months of duty remaining at the time of surgery” according to Walter Reed Army Medical Center’s Center for Refractive Surgery. Title 10 National Guard and reserve components are also eligible for surgery under the WRESP. However, other National Guard and reserve components are not eligible at this time.
The services’ application and screening processes for CRS and LASIK surgery follow common procedures.
Generally, the prospective service man or woman for surgery who has his or her commanding officer’s approval is initially evaluated by an optometrist with an expertise in identifying good candidates for a surgery process. The candidate’s consultation request is then screened at the closest RS facility.
As CRS and LASIK surgery are warfighter’s programs, the services have additional processing steps for warfare community members. The Navy, for example, has a four-tier priority system. Aviators, divers and special warfare community members have the highest priority (Group 1).
Given the demand for these surgical procedures, even a priority-screened candidate will typically be placed on a waiting list. Walter Reed CRS notes that for one of its service’s priority-screened patients, “The current waiting time [for refractive surgery] is approximately 12 months from the time your application is accepted.” The servicemembers who are eligible for these procedures benefit from an expanding array of technologies.
TECHNOLOGIES
“I feel that I am privileged to be practicing surgery at this day and age. The technology available to me as a surgeon is amazing,” reflected the Navy’s Tanzer. “I have an extremely high level of confidence in the technology that we can offer to our prospective patients. I need to have that level of confidence because of the unique population that we care for in the military. All patients that we care for are important. But when we consider the highrisk patients that the military has spent millions of dollars training for a certain mission, the care of their eyes when we conduct the surgery is paramount,” he added.
One technology found in the Navy’s RS clinics is an excimer laser, which helps the surgeon reshape the cornea. The laser is made by Visx, an Advanced Medical Optics (AMO)-owned company.
“We have entered a new era of surgery where the majority of our patients receive treatments that are controlled with a wavefront pattern—this is akin to a fingerprint of the eye,” said Tanzer. “So, now we have the ability to measure and map all of the optical aberrations and distortions in the individual system. Those aberrations and distortions can be linked, or transferred, to the laser and corrected for using the wave-front guided laser approach,” he added.
The technology supporting LASIK surgery has advanced from using a mechanical micro-keratome (a precision instrument with an oscillating blade) that would create a partial flap in the process, to a laser keratome.
“Based on studies we performed here at Naval Medical Center San Diego, that provides not only a safer way to pursue LASIK, but better visual outcomes, better functional vision and better quality vision,” he remarked.
Laser keratomes used by the Navy are made by IntraLase. In March of this year, the company announced its approval of a merger with AMO, the new majority shareholder.
A second service insight on the latest technology available in RS centers was provided by the Air Force’s Reilly. “Our current technology is truly amazing; we have a 3-D eyetracker that can track the eye 1,000 times faster than you can move your eye; we have iris-recognition software that identifies the correct treatment on the correct eye to ensure the wrong treatment can’t be performed on the patient. We have wave-scan technology that can identify optical aberrations of your eye that glasses can’t even correct and we use our lasers to correct those aberrations,” he said.
For its part, industry provides cutting- edge technologies to support surgical options available to the military community. In one case, AMO’s Advanced CustomVue laser vision correction technology is combined with its IntraLase Method, and is a procedure available for airmen, sailors, soldiers and Marines.
“The Advanced CustomVue laser vision correction procedure stands in a class of its own with the broadest range of FDAapproved indications,” opined information from an AMO spokesperson. The information also stated, “When combined with the power and precision of the IntraLase Method, the Advanced CustomVue procedure represents the most advanced LASIK procedure available to patients today. The IntraLase FS laser, the first technology for a blade-free LASIK procedure, replaces the handheld microkeratome blade historically used in creating LASIK corneal flaps—the first step of the procedure—with a computer guided, ultra-fast femtosecond laser.”
A femtosecond laser uses an infrared wavelength and has a short burst (1-quadrillionth of a second). The laser requires less energy to produce photodistruption compared to longer-pulse lasers. A femtosecond laser creates plasma inside transparent tissues, such as a cornea, while leaving the surrounding material (surface tissue) cool.
“The IntraLase laser virtually eliminates the majority of the most severe sight-threatening LASIK complications related to use of the microkeratome and, by creating an optimal corneal surface below the flap, provides for better visual outcomes,” pointed out the information from an AMO spokesperson.
The military-industry team is also focused on improving the vision of those servicemembers who do not qualify for the previously described procedures.
ALTERNATIVE PROCEDURE
Servicemembers who are not good candidates for two CRS procedures, PRK or LASEK, based on their pre-operative examinations, may be better-suited to obtain an implantable collamer lens (ICL), better known as a phakic intraocular lens.
“This is an intraocular procedure, where we insert a lens inside the eye, like we would do during cataract surgery, except we leave the natural lens alone,” pointed out the Navy’s Tanzer.
The benefit of this procedure is that it preserves the patient’s ability to focus and the surgery does not disrupt the natural state— the curvature—of the cornea.
“We have been fortunate enough to have been part of those clinical trials of that technology here at Naval Medical Center San Diego for several years. The results of this technology are just fantastic. This is a very viable and feasible alternative to corneal refractive surgery for patients who would not be candidates for that type of surgery [corneal-based refractive surgery],” concluded Tanzer.
At press time, the procedure to insert ICLs was FDA-approved, and ICLs had been implanted in several sailors and Marines. ♦