Abstract
Purpose:
To compare rifle marksmanship performance after WFG vs. WFO refractive surgeries.
Methods:
In this prospective study, 55 myopic U.S. military service members with mean age 30.0 ±6.7 years and mean manifest refractive spherical equivalent -3.77 ±1.43 diopters undergoing either PRK or LASIK were randomized to receive either WFG (VISX CustomVue STAR S4 IR) or WFO (Wavelight Allegretto Wave EyeQ excimer laser systems) treatment. Marksmanship performance was evaluated preoperatively and at 6 weeks (W) and 6 months (M) postoperatively. Participants were asked to fire an M16-A4 rifle under three conditions: iron sight under low light (approximately 1 cd/m2); night vision goggle (NVG); and forward-looking infrared (FLIR) thermal sight under “starlight” (approximately 0.001 cd/m2). Pre- and postoperative firing range scores were compared between treatment groups at each time point. Four groups (WFG PRK, n=13; WFG LASIK, n=14; WFO PRK, n=14; and WFO LASIK, n=14) were compared using the Kruskal-Wallis test. For multiple comparison, a Bonferroni adjusted p-value<0.02 was considered statistically significant.
Results:
There was no significant difference in firing scores among the treatment groups preoperatively except when using FLIR thermal sight (P=0.01). Post-hoc analysis revealed firing scores when using FLIR thermal sight in WFG PRK group was significantly higher than that in WFG LASIK group (P=0.017), preoperatively. At 6W postoperatively, there was a significant difference in firing scores using iron sight among the groups (P<0.01) but not in firing scores using NVG and FLIR thermal sight. Further analysis revealed firing scores using iron sight in WFG PRK and WFO PRK groups were significantly higher than that in WFG LASIK group (P=0.018 and P=0.015, respectively) 6W postoperatively. The firing scores using iron sight, NVG and FLIR were comparable for all groups at 6M postoperatively.
Conclusions:
WFG and WFO PRK may offer a short-term advantage over WFG LASIK in low light firing performance. Overall, using WFG or WFO treatment in either PRK or LASIK results in comparable rifle marksmanship performance in U.S. soldiers after surgery. Vision enhancers, like NVG and FLIR thermal sight, in rifle marksmanship performance are not hampered by refractive surgery.