Subjective Dry Eye Symptoms and Objective Ocular Surface Signs in a Civil Air Crew Population: A Cross-Sectional Study

Abstract

Background Aviation professionals are often exposed to conditions such as low cabin air pressure, reduced humidity, and prolonged artificial lighting, which may predispose them to dry eye disease (DED). We therefore designed a cross-sectional study with three primary objectives. Our first aim was to determine the prevalence of subjective dry eye symptoms among civil flight personnel. To achieve this, we administered the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire. Second, we performed ocular examinations to assess objective DED indicators, such as the Schirmer’s-1 (SCH-1) test and tear film break-up time (TBUT). We then correlated the results of these objective tests with the subjective symptoms reported by the participants. Last, we aimed to identify the independent risk factors for positive SCH-1 and TBUT results among aircrew personnel who did not report subjective dry eye symptoms. Methods The study sample consisted of 189 aircrew personnel (94 men and 95 women; mean age: 35.8 ± 10.4 years). They completed the SPEED questionnaire, a tool for assessing ocular surface symptoms. Participants' symptoms were classified as normal (SPEED scores 0-6), moderate (SPEED scores 7-15), or severe (SPEED scores 16-28). The objective assessment included the SCH-1 test for tear production and the TBUT test for tear film quality. Results A significant majority of participants (n = 165; 87.3%) did not report any subjective symptoms of DED. However, 12.2% (n = 23) and 0.5% (n = 1) of the study subjects experienced moderate and severe symptoms, respectively. The SCH-1 test and TBUT test were positive in 25.4% (n = 48) and 24.9% (n = 47) of the participants, respectively. Interestingly, among the aircrew personnel who did not report any subjective dry eye symptoms (SPEED scores 0-6), 18.8% (n = 31) and 17.6% (n = 29) showed abnormal results on the SCH-1 test and TBUT, respectively. Age was identified as the only independent predictor of a positive TBUT (odds ratio = 1.05, 95% confidence interval (CI) = 1.01-1.08, p = 0.01), with a borderline significant association with a positive SCH-1 test (odds ratio = 1.03, 95% CI = 0.99-1.07, p = 0.06). Conclusions The disparity between subjective symptoms and objective tests emphasizes the significance of incorporating objective measures for screening and diagnosing DED in civil flight personnel. If independently confirmed by future research, our findings could potentially lead to the routine implementation of surveillance protocols that incorporate objective DED indicators. Moreover, as age emerged as an independent predictor of positive results on objective tests, it is crucial to consider age-specific screening strategies.

Occupational Health Challenges for Aviation Workers Amid the Changing Climate: A Narrative Review

“…Although some authors were unable to detect UV-A or UV-B radiation (wavelength: 280-315 nm) in airplane cabins or cockpits [19], there is increasing evidence that pilots carry genomic signatures consistent with UV-induced DNA damage [20,21]. This observation is further strengthened by occupational health studies showing that this professional category is at increased risk of UV-related disorders, including skin cancer [22,23], nuclear cataract [24], and dry eye disease [25]. Remarkably, a meta-analysis by Sanlorenzo et al [23] revealed that pilots have approximately twice the incidence of malignant melanoma compared to the general population.…”

“…UV radiation exposure can also result in increased oxidative stress and inflammation on the ocular surface, which are underlying mechanisms in the pathogenesis of dry eye disease [26]. This condition often manifests symptomatically with feelings of irritation, grittiness, or visual disturbances but can also occur asymptomatically, including among aircrew personnel [25]. In the context of climate change, the health hazards posed by UV radiation are becoming a more pressing issue for aviation workers due to the thinning of the stratospheric ozone layer [27].…”