EyeWorld Asia-Pacific March 2020 Issue

REFRACTIVE EWAP MARCH 2020 35 Contact information Cason: john.b.cason.mil This article originally appeared in the November 2019 issue of EyeWorld . It has been slightly modified and appears here with permission from the ASCRS Ophthalmic Services Corp. by Maxine Lipner EyeWorld Senior Contributing Writer I nvestigators in a recent study evaluated how military personnel who had PRK or LASIK fared in the long term, finding that nearly half continued to enjoy 20/20 vision for a mean of 8.2 years after refractive surgery. 1 The study was a retrospective look at the many refractive surgery cases the military handles. “In the Department of Defense, we do about 40,000 patients per year, and in the Navy, it’s just shy of 10,000 cases per year,” said John Cason, MD. “We’re doing all of this refractive surgery and have been since 1993 when Dr. [Steven] Schallhorn first started doing the procedures here in San Diego.” Operational importance Unlike civilian patients who may have personal reasons for undergoing refractive procedures, in the military it is done primarily for operational reasons, Dr. Cason said. “For us, it’s a medical readiness issue so we can deploy to austere environments,” he said, adding that even when it comes to flying an airplane, a contact lens is not good enough since this could fall out. Likewise, wearing spectacles may interfere with protective equipment, such as the seal of a gas mask. In short, the military perceives refractive surgery as a very noble cause, Dr. Cason stressed. “In general, we view our uncorrected vision as a means to be able to see the enemy before the enemy sees us,” he said. It is incumbent on the military to make sure that the results are not only safe and effective in the short term but also the long term. While short-term studies indicate that 97–98% of patients enjoy 20/20 acuity, there are not many refractive studies in general that examine the long-term effects, with most going out 2–3 years, Dr. Cason said. One exception is a study 2 by Rosman et al. that examined 10-year data on PRK, Dr Cason noted, adding that it showed similar results to the recent study and thus indicates that the cornea was very stable after refractive surgery. Military long view The recent study by Dr. Cason and co-investigators included 160 eyes followed up for a period as long as 17 years. “The average drift was about 1/10th Examining long-term refractive results in the military Dr. Cason performing refractive surgery on a member of the military. Source: John Cason, MD