Traditional clinical tests such as uncorrected and corrected visual acuities and manifest refraction are commonly used to obtain benchmarks for safety, efficacy, and the overall success of refractive surgery. Although these are the primary considerations in standardized reporting of outcomes, clinicians and researchers alike have acknowledged the importance of supplementing these tests with patient-reported outcomes to render a complete assessment of the treatment performed.1–3 Tools for patient-reported outcomes such as quality of life questionnaires may be able to capture and monitor visual performance following surgery, which may not show up in conventional clinical tests, such as difficulties while performing common activities such as reading and driving.
For those in the military, the impact of refractive surgery may also be reflected in their perceived ability to perform occupation-specific tasks. In fact, the U.S military adopted the Warfighter Refractive Eye Surgery Program for eligible active duty service members because it recognized the potential benefits of refractive surgery in enhancing the readiness and effectiveness of individual service members and their military units. Although the safety and efficacy of refractive surgery have been widely demonstrated through standard clinical assessments in military and civilian population reports, studies on occupation-specific quality of life, satisfaction, and performance4–8 are relatively limited. Military service members are most likely to be subjected to unique visual demands, especially during military operations occurring in varying low light conditions, adverse environmental conditions, or even in critical situations calling for instantaneous life and death decisions. Therefore, additional evaluation could provide further insight into the effect of refractive surgery on their subjective visual function and performance. In this study, we assessed the perception of active duty U.S. military service members undergoing refractive surgery on their vision-related quality of life and military readiness and capabilities.
Patients and Methods
The study was conducted at the Warfigher Refractive Eye Surgery Program and Research Center (WRESPRC), Fort Belvoir Community Hospital, Fort Belvoir, Virginia. The protocol was reviewed and approved by the institutional review board at Walter Reed National Military Medical Center, Bethesda, Maryland, prior to study initiation. Active duty U.S. military service members who were at least 21 years old, with either myopia or hyperopia, with or without astigmatism, undergoing primary refractive surgery at WRESP-RC were included in the study. A key exclusionary criterion was a previous intraocular or corneal surgery in either eye. Written informed consent was obtained from each participant before any study procedure was administered.
Enrolled participants were asked to complete a questionnaire adapted from the U.S. Army Refractive Surgery questionnaire8 preoperatively and at 6 months postoperatively. On a 5-point scale (1 = very bad, 5 = very good), the participants were asked how they felt their vision affected their military readiness and capabilities. One additional item in the postoperative questionnaire was to rate their satisfaction with the refractive surgery (Table 1). An initial assessment of the validity and reliability of the military questionnaire was performed on the first 100 of 360 enrolled participants. To evaluate test–retest reliability, the questionnaire was administered twice preoperatively and then twice at 6 months postoperatively. The time interval for the first and second completion of the questionnaire ranged from 7 to 30 days.
Items in the Military Performance Questionnaire Assessed on a 5-Point Scale
In addition to the military performance questionnaire, the National Eye Institute Refractive Error Quality of Life Instrument (NEI RQL-42)9,10 was administered to the remaining 260 of the 360 participants preoperatively and at 6 months postoperatively.
At the time of the study, the refractive surgery procedures available at the study site included photorefractive keratectomy (PRK), LASIK, and phakic intraocular lens (IOL) implantation. In PRK, corneal epithelial debridement was performed using the Amoils brush scrubber (Innovative Excimer Solutions, Inc., Toronto, Ontario, Canada). Prophylactic mitomycin C was applied according to individual parameters set by the surgeons. In LASIK, a superior-hinged corneal flap was created using the iFS Intra-Lase femtosecond laser (Johnson & Johnson Vision, Jacksonville, FL). All photoablative procedures were performed using the WaveLight Allegretto Wave Eye-Q excimer laser (Alcon Laboratories, Inc., Fort Worth, TX). A posterior chamber Visian Implantable Collamer Lens (ICL; STAAR Surgical, Monrovia, CA) was used in phakic IOL surgery.
The statistical analysis was performed using SPSS software (version 21; IBM Corporation, Armonk, NY). The internal consistency of the military performance questionnaire items was measured by Cronbach's alpha. The test–retest reliability was assessed by estimating the intraclass correlation coefficient for the overall score. Criterion validity was evaluated by calculating the Pearson correlation coefficients between each questionnaire item and clinical variables including manifest spherical equivalent (MSE) and corrected distance visual acuity (CDVA) of the better eye. The NEI RQL-42 responses were recoded as scores ranging from 0% to 100%, with higher scores indicating better quality of life.11 The averages for items within each scale were calculated to determine the scores for the 13 scales of the NEI RQL-42: clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limitations, glare, symptoms, dependence on correction, worry, suboptimal correction, appearance, and satisfaction with correction. The Wilcoxon signed-ranked test was used to compare preoperative to postoperative individual military performance item scores and overall mean scores, as well as the scores for each NEI RQL-42 scale. A P value of less than .05 was considered statistically significant.
Refractive surgery offers potential operational benefits over corrective lenses for service members with refractive error. Optical correction with eyeglasses in a combat environment has significant disadvantages because dust, sweat, and other substances may accumulate on lenses. Eyeglasses can also interfere with protective masks, specialized headgear, and vision augmentation devices, whereas optical inserts for ballistic eyewear can also become fogged, scratched, broken, or lost. Contact lenses could eliminate concerns inherent to eyeglasses; however, contact lenses are prohibited during deployments due to issues associated with lens overwear, poor hygienic conditions, and increased risk of infections. For these reasons, refractive surgery has been made available to eligible active duty military service members as a readiness option for vision enhancement.
In this study, the responses among service members were overwhelmingly positive. Based on the results, the respondents felt that there was a significant improvement in their overall individual readiness and ability to contribute to their unit's mission postoperatively. In terms of specific visual tasks or requirements, the participants also thought that they performed or met the requirements better after undergoing refractive surgery. Weapon sighting ability, ability to use night vision goggles, nuclear, biological, and chemical equipment, and personal mask were improved postoperatively, which could be attributed to elimination of visual impediments associated with eyeglasses or optical inserts. Furthermore, their ability to meet optical support requirements were better postoperatively because the need to order, replace, or repair prescription eyeglasses and inserts were most likely reduced. Their ability to function at night and weather extreme environmental conditions (sand, fog, smoke, rain, etc.) also significantly improved postoperatively. This may be owed in part to the use of an advanced excimer laser platform for PRK and LASIK, both of which collectively comprised the majority of surgeries in the study. Advanced treatment platforms attempt to limit induction of higher order aberrations, thereby reducing the degradation of contrast sensitivity and night vision symptoms such as glare and halo.12–14
The general perception among service members on their capabilities and readiness after receiving refractive surgery seems to be consistent with previous findings. The current findings were similar to the results of a survey performed on soldiers returning from deployment in Afghanistan, Iraq, or Kuwait after the first few years (2000–2003) of implementing the U.S. Army Warfighter Refractive Eye Surgery Program. Hammond et al.8 reported that among 175 soldiers who completed a post-deployment questionnaire, 93.1% felt the surgery enhanced their ability to contribute to their unit's mission and 93.7% felt their overall individual readiness was better or much better after surgery. Likewise, in a study by Tanzer et al.7 on naval aviators undergoing LASIK, 292 of 305 (95.8%) participants felt that LASIK had helped their effectiveness as naval aviators.
The perceived gains from refractive surgery could be further demonstrated in this study by the responses of service members regarding vision-related quality of life. Quality of life was significantly improved postoperatively based on a higher average of overall NEI RQL-42 scores postoperatively. Clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limitations, glare, dependence on correction, worry, suboptimal correction, and appearance were also better postoperatively. Symptoms that assessed discomfort, dryness, tearing, itching, or soreness, if experienced at all, did not show a significant change from preoperative baseline. Although our study was not limited to LASIK, the results of the NEI RQL-42 reinforced earlier findings of the U.S. Food and Drug Administration-initiated Patient-Reported Outcomes With LASIK (PROWL) studies.1 In both the PROWL-1 and PROWL-2 studies, which comprised active duty U.S. Navy personnel and civilians, respectively, the investigators found only a few participants developed dry eye symptoms based on their Ocular Surface Disease Index scores. In terms of visual symptoms such as double images, glare, halos, and starbursts, the PROWL studies also found that the overall prevalence of visual symptoms decreased. Although the investigators found that there was a large percentage of participants without visual symptoms preoperatively who developed visual symptoms postoperatively, only a few participants reported a substantial impact from the symptoms and that less than 1% of PROWL-1 participants had difficulty performing usual activities due to visual symptoms.
The U.S. military refractive surgery program has been remarkably successful since inception, performing approximately 35,000 procedures in 2015 alone.15 Indeed, the current study also revealed an extremely high satisfaction rate among participants. Almost 99% of the study participants (167 of 169) indicated willingness to undergo surgery if they had to do it again. Of the 2 participants who replied “no,” one underwent PRK and one underwent LASIK. Furthermore, satisfaction with correction was significantly higher postoperatively among those who completed the NEI RQL-42 questionnaire. Similarly, Tanzer et al.7 reported 301 (99.6%) of 305 participants would recommend LASIK to naval aviators, with 300 participants (98.2%) stating they would definitely recommend LASIK to a fellow naval aviator. More recently, the PROWL-1 study also observed high mean satisfaction scores and low rate of dissatisfaction with surgery at 1% at 3 months and 2% at 6 months postoperatively.1
It may be argued that the high satisfaction rate could be driven by the fact that the surgery has no monetary cost to military personnel, so they might be less critical compared to a civilian patient who would be spending several thousand dollars for surgery. Although it would seem that meeting financial expectations may be more relevant when referring to the satisfaction of paying patients, it should be pointed out that refractive surgery for military personnel is not cost-free. Under the WRESP, refractive surgery is considered a military readiness enhancement rather than a cosmetic procedure. For example, in the Army, combat arms and deploying soldiers regardless of specialty are given highest priority. As Pasquali et al.5 suggested, satisfaction is multidimensional and is also dependent on whether the physical and emotional expectations are met. For example, physicians who may tend to be more skeptical of and objective about refractive surgery also responded positively, with a 95.8% total satisfaction rate.5 Furthermore, McGhee et al.16 found improved unaided vision ranked highest for motivation for refractive surgery but offered that although patients may be satisfied with the surgery overall, they may not necessarily be satisfied with subcomponents of outcomes.
In our study, we demonstrated that there are physical and emotional advantages of refractive surgery from the military personnel standpoint as seen in the improved scores postoperatively, especially when asked about a specific visual task or requirement (Figure 1). However, it is also worth noting that there was a cohort of respondents whose scores were unchanged postoperatively when asked about their overall individual readiness and ability to contribute to their unit's mission. On further assessment, of the 70 respondents whose scores were unchanged when asked about overall individual readiness postoperatively, 62 (88.6%) had already given their preoperative readiness a score of 5 (very good) and the remaining 8 (11.4%) had given a score of 4 (good). Similarly, of those whose scores were unchanged when asked about ability to contribute to unit's mission, 87 (94.6%) had ranked their preoperative ability as 5 (very good) and the remaining 5 (5.4%) respondents ranked their readiness as 4 (good). We also found a small percentage had worse scores: 1.8% for overall individual readiness, 4.1% for contribute to unit's mission, 0% for use of night vision goggles, 7.2% for function at night, 0.8% for weapons sighting ability, 0.9% for employment of nuclear, biological, and chemical equipment, 3.9% for weather extreme environmental conditions, and 6.3% for optical support in theater. Among 24 participants who had worse scores in at least one of these specific tasks or requirements, 16 had PRK and 8 had LASIK. They did not appear to be procedure dependent because these numbers represented 15% and 13.1% of total respondents after PRK and LASIK, respectively. All participants, except for one who had LASIK, would undergo surgery if asked to do it over.
The current study was limited primarily by a low follow-up response rate. All of our participants completed the questionnaires at baseline and, despite appropriate efforts including allotting a ±1 month follow-up period, slightly more than half (52.7%) of them were unable to accomplish the questionnaire at their 6-month postoperative timeframe. The drawback was most likely due to the study participants' “nature of work.” Although participants were offered options to complete the questionnaires off-site, different job requirements such as deployments and training exercises might have precluded them from doing so on time. Miller and Aharoni17 also identified other factors for nonresponse in military surveys, including technological and situational barriers such as computer access issues, junk-mail settings, perceptions of privacy and anonymity, and motivational factors such as perceived lack of time, incentive, feedback, interest on topic, survey length, and survey fatigue.17 Considering active duty service members are generally deployable at least 90 days following refractive surgery, the study was still able to obtain a sizeable number of responses at 6 months postoperatively.
Assessing for potential nonresponse bias, the study did not find a significant difference in refractive error or PRK/LASIK proportion between postoperative respondents versus nonrespondents. However, the study did find that the participants who were unable to complete the follow-up questionnaires tended to be younger compared to those who did. This observation is not uncommon in surveys involving U.S. military personnel. For example, in a 2012 survey performed on U.S. Air Force military personnel on the role of information and communications technologies on airmen's social and psychological well-being, airmen in the youngest age group (18 to 24 years) were the least likely to respond.17 Although disproportionate responses among age groups could be a cause for concern to some degree because the younger age group may be underrepresented, Miller and Aharoni explained that nonresponse bias would be present only when respondents and nonrespondents would have answered differently and that the difference in characteristics would be relevant to the study.17 In the current study, we did not find significant differences in the score for military readiness and capabilities between respondents and nonrespondents in either the younger (< 30 years) or older (30 and older) study population. Moreover, in both respondents and nonrespondents, we did not find significant differences in the scores for the same outcome measures between the younger and older subgroups.
Participants were also enrolled consecutively irrespective of the surgery planned. Because PRK and LASIK were the predominant procedures, a further limitation of the study was that no data could be derived to determine whether there were any variations in outcomes following laser refractive surgery procedures compared to outcomes following phakic IOL implantation. If not eligible for refractive surgery otherwise, phakic IOL implantation is a generally accepted alternative among military refractive surgeons, although there are service-specific restrictions. Exploratory analysis revealed no significant differences in the postoperative military readiness and capabilities scores of those who had PRK compared to those who had LASIK (P > .092).
The findings of this study offer additional insight into the effect of refractive surgery on visual function and performance. The perceived enhanced capabilities and readiness, as well as improved quality of life, seem to further substantiate the safety and efficacy of refractive surgery, particularly for individuals in the armed forces. For this patient population, it is not unreasonable to think that the gains from spectacle independence through refractive surgery are not only confidence and morale boosters but also a significant operational and, more importantly, survival advantage. The benefits associated with refractive surgery might be applicable to other patient cohorts such as law enforcement and firefighters, whose occupations may also be associated with various visually demanding tasks.