Dry eye disease is a multifactorial disorder of the ocular surface characterized by loss of tear-film homeostasis and accompanied by ocular symptoms; tear-film instability, hyperosmolarity, inflammation, ocular-surface damage, and neurosensory abnormalities may have etiologic roles [1][2].

Dry eye disease is common, and its reported prevalence varies substantially with the population studied, diagnostic criteria, and study design [3].

Estimates from population-based and selected clinical or occupational samples vary widely across Western and Asian settings [3]-[10]. Hospital-based African studies also indicate a substantial burden [11]-[14].

Studies from the Democratic Republic of the Congo have described dry-eye presentations in hospital populations and among patients with glaucoma [11][14], but evidence concerning cosmetic eyelash procedures remains limited.

Eyelash extensions place synthetic fibers, adhesives, removal agents, and fixation materials close to the eyelid margin and ocular surface. A retrospective Japanese series of 107 symptomatic users described predominantly keratoconjunctivitis and allergic blepharitis associated with extension procedures [15]. More recently, a prospective study of 32 participants documented acute symptoms and corneal staining after application, followed by a short-term reduction in noninvasive tear-film break-up time [16]. Neither study directly established chronic aqueous tear deficiency, and comparable evidence from African populations is scarce.

This study therefore compared Schirmer I values, fluorescein TFBUT, and ocular-surface symptoms between women wearing eyelash extensions and women not wearing them in Kinshasa.

As reported in Table 1, the distributions of age, education, marital status, and occupation were identical between groups (all p = 1.000). Consequently, no statistically significant difference was observed regarding these sociodemographic characteristics.

Table 1. Sociodemographic characteristics by eyelash-extension status.

Compared with controls, women wearing eyelash extensions had a shorter mean TFBUT (10.6 ± 2.8 vs 12.1 ± 2.3 s), a higher mean Schirmer I value (21.3 ± 5.1 vs 17.5 ± 4.5 mm), and a higher mean OSDI score (15.7 ± 2.3 vs 8.1 ± 1.9) (Table 2).

Table 2. Tear-function measurements and OSDI scores by eyelash-extension status.

The reported distribution of OSDI severity categories differed between groups (Table 3).

Table 3. Reported OSDI severity categories by eyelash-extension status.

Severe symptoms were reported for 205 of 350 women (58.6%) in the eyelash-extension group and 42 of 350 (12.0%) in controls. A normal category was reported for 15 women (4.3%) in the eyelash-extension group and 240 (68.6%) in controls; mild and moderate categories accounted for 22.0% and 15.1% of the extension group and 8.0% and 11.4% of controls, respectively.

In this comparative cross-sectional study of 700 women in Kinshasa, women wearing eyelash extensions had a shorter mean TFBUT and a higher mean OSDI score than women without extensions. Based on the values reported in Table 2, the extension group also had a higher mean Schirmer I value.

The differences were statistically significant, but their clinical importance cannot be determined from group means alone, and the study did not apply a prespecified diagnostic algorithm for dry eye disease.

The higher Schirmer I value may reflect reflex tearing in response to ocular-surface irritation rather than superior baseline lacrimal function. When performed without topical anesthesia, Schirmer I testing captures both basal and reflex secretion and has substantial biological and measurement variability [19].

Because the timing of extension application, adhesive and removal products, and concurrent ocular irritation were not characterized, the mechanism underlying the Schirmer result remains speculative.

The shorter TFBUT is consistent with the prospective observations of Han et al., who found a transient reduction in noninvasive tear-film break-up time after eyelash-extension application [16]. However, their study also showed time-dependent changes in tear meniscus height, indicating that the interval since application may materially influence tear measurements.

Previous evidence indicates that ocular effects are heterogeneous. Amano et al. described mainly chemical or allergic complications among symptomatic clinic attendees [15], whereas Han et al. observed acute symptoms and corneal staining followed by short-term tear-film instability [16]. Neither selected sample permits estimation of population incidence or establishes chronic aqueous tear deficiency.

The higher mean OSDI score suggests a greater symptom burden among women wearing extensions. Nevertheless, symptom scores and tear-film signs are not interchangeable, and these results should not be interpreted as the prevalence of clinically diagnosed dry eye disease.

The observed differences may reflect extension-related exposure, but they may also reflect selection, unmeasured confounding, or other differences between the recruitment settings.

Accordingly, the cross-sectional associations reported here do not establish causation.

Portable anterior-segment video may also support more standardized ocular-surface assessment where access to ophthalmologists is limited. An SEC-based artificial intelligence model has estimated fluorescein tear-film break-up from video and supported dry-eye classification [20]. More recently, artificial intelligence has been explored for estimating tear meniscus height from paired SEC videos and anterior-segment optical coherence tomography, although the reported error indicates that further refinement is required before routine clinical use [21]. Image-processing studies also show that enhancement must be optimized for each endpoint because stronger processing can reduce reliability for some ocular-surface findings [22]. Collectively, these studies support technical feasibility but not clinical equivalence or cross-population generalizability.

Store-and-forward SEC workflows have been reported for remote assessment of an ocular chemical injury and for anterior-segment screening on a remote island [23][24], while a rural cataract case illustrates continuing access gaps in resource-limited settings [25]. Consistent with a recent narrative review, smartphone-based slit-lamp systems should currently be viewed as adjuncts to, rather than replacements for, comprehensive in-person examination [26]. Future studies in Kinshasa should combine standardized symptoms and tear-function measures with masked remote video grading and prespecified artificial-intelligence endpoints. Participant-level data partitioning, a conventional slit-lamp reference standard, calibration, and external validation in Central African populations will be essential before clinical deployment.

This study’s strengths include its large sample and its focus on a Central African population that has been underrepresented in ocular-surface research. Several limitations should, however, be considered.

First, the cross-sectional design precludes temporal inference. Participants with extensions were recruited from salons, whereas controls were hospital attendees, creating a substantial risk of selection bias. Matching was not described, and the analysis did not adjust for potential confounders.

Second, duration and frequency of extension wear, time since application, adhesive and removal products, contact-lens use, other cosmetics, systemic conditions such as diabetes [27], ocular conditions, medications, and environmental exposures were not reported. These factors could influence symptoms and tear measurements. Measurement details, examiner masking, and the participant or eye as the unit of analysis also require complete reporting. Finally, the single-city setting limits generalizability.

In this cross-sectional study, women wearing eyelash extensions had higher Schirmer I values and OSDI scores and shorter TFBUT than controls. These associations do not establish causation or confirm a diagnosis of dry eye disease.

Clinicians evaluating ocular-surface symptoms should ask about eyelash-extension use and counsel users about possible ocular-surface associations and warning symptoms that warrant examination. These findings do not establish that eyelash extensions cause dry eye disease.

The authors thank all women who participated in the study.

Conceptualization and methodology: David Kayembe Lubeji and Léon Muamba Nkashama; investigation and data curation: Léon Muamba Nkashama; formal analysis: Léon Muamba Nkashama; writing—original draft: Léon Muamba Nkashama; writing—review and editing: Shintaro Nakayama, Eisuke Shimizu, and Ryota Yokoiwa.