Visual performance of U.S military servicemembers (USM) in identification of infrared targets after wavefront-guided (WFG) and wavefront-optimized (WFO) photorefractive keratectomy (PRK) and LASIK

Abstract

Purpose : To assess the probability of identification (PID) of combat vehicles in infrared images by USM before and after undergoing WFG and WFO PRK and LASIK.

Methods : In this prospective study, USM (mean age 29.9 ±5.5 years) with myopia or myopic astigmatism electing to undergo PRK or LASIK (mean manifest refractive spherical equivalent -3.78 ±1.44 diopters ) were randomized to receive either WFG (VISX CustomVue STAR S4 IR, Abbott Medical Optics) or WFO surgery (Wavelight Allegretto Wave EyeQ, Alcon Surgical). Pre- and postop clinical exams included visual acuity tests, refraction, and slit lamp exam. USM also underwent computer based experiments, preop with optical correction and at 6 weeks (W) and 6 months (M) postop without correction, to assess PID: 1) with infrared imagery captured in multiple wavebands and digitally fused using an image-averaging algorithm; and 2) with varying target contrasts. The PID for each experiment and among the treatment groups were compared using a repeated measures analysis of variance. Association of PID with the postop visual acuity, residual refractive error and surgery was analyzed using linear regression. A p-value <0.05 considered statistically significant.

Results : Of the 53 participants, 14 underwent WFG PRK, 12 WFG LASIK, 13 WFO PRK and 14 WFO LASIK. At 6M postop, all eyes achieved uncorrected distance visual acuity (UDVA) of 20/20 or better except for one eye treated with WFO PRK. There was no loss of more than one line of corrected distance visual acuity. In identifying combat vehicles, there was no significant difference among the treatment groups in PID over time whether the targets in different wavebands were fused (p=0.92) or the target mean, background mean, and standard deviation of the target signatures were altered (p=0.59). There were no significant associations between the 6M UDVA, MSE as well as the type of surgery and the PID for combat vehicles in fused wavebands (p=0.72) or in varying contrasts (p=0.72).

Conclusions : The application of WFG and WFO technologies for PRK and LASIK results in excellent refractive outcomes. In the context of military operations, these techniques are effective in reducing soldiers' dependence on corrective lenses while maintaining their ability to perform military relevant tasks, such as infrared target identification.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.