To investigate the effect of time of day on tear evaporation rate (TER) and tear break-up time, and its possible relationship with the concentration of inflammatory tear molecules (cytokines) in healthy subjects. Participants with healthy ocular surfaces attended 3 visits, including the screening visit (V0), the 2nd visit (V1) and the 3rd visit (V2). There were 7-day intervals between visits. Participants with Dry Eye Disease (DED) were excluded by using appropriate clinical tests during V0. Clinical evaluation (TER and Non-Invasive Tear Break-Up Time (NITBUT)) and tear collection were performed during V1 and V2, between 9 and 10AM and 3-4PM. The relative humidity and temperature of the examination room were also measured. The tear fluid concentrations of 15 cytokines were measured by multiplex bead analysis. Seven men and 10 women (mean age ± S.D; 25.1 ± 6.63 years old) participated in the study. There were no differences in neither the TER and NITBUT outcomes, nor humidity and temperature among times or visits. Eleven out of the 15 cytokines measured were detectable in tear fluids in > 50% of the participants. In the tear levels, no significant (p > 0.05) inter- and/or intra-day differences were detected for EGF, fractalkine, IL-1RA, IL-1β and IP-10. However, significant inter-day differences were found in the tear levels of IL-10 (p = 0.027), IFN-γ (p = 0.035) and TNF-α(p = 0.04) and intra-day differences in the tear levels of IL-8/CXCL8 (p = 0.034) and MCP-1 (p = 0.002). A significant correlation between TER and IL1-β, IL-2, and Fractalkine (p = 0.03, p = 0.03 and p = 0.046, respectively) was found at V1. NITBUT and TER values had no significant variability over the course of a day (AM versus PM), or on different days in healthy participants when humidity and temperature were constant. However, some tear molecule levels did show inter- and intra-day variability, having an inconsistent and moderate correlation with TER diurnal variation.

Purpose: To study whether contact lens (CL) discomfort and some properties of soft CL materials are associated with alterations in the nerve fibers morphology and density of dendritic cells of the corneal sub-basal nerve plexus. Materials and Methods: Forty soft CL wearers and 20 non-CL wearers were included. The Contact Lens Dry Eye Questionnaire-short form was administered to divide CL wearers based on their symptoms (20 symptomatic and 20 asymptomatic CL wearers were included). The CL material properties considered were the CL material type (16 hydrogel and 24 silicone hydrogel CL wearers were included), water content, oxygen transmissibility, and modulus of elasticity. Confocal microscopy was performed, and the number and density of corneal nerves, density of nerve branches, grade of nerve tortuosity, and density of dendritic cells were analyzed. The effects of CL discomfort and CL material properties on the confocal microscopy parameters were analyzed. Results: No significant differences were found among symptomatic and asymptomatic CL wearers and non-CL wearers in any of the confocal microscopy parameters evaluated. The density of dendritic cells was higher in the hydrogel CL wearers compared to the silicone hydrogel CL wearers and non-CL wearers (p = 0.002). The density of dendritic cells tended to be higher as the oxygen transmissibility decreased (β = −0.40, p = 0.07). Conclusions: CL discomfort appears not to be associated with alterations in the corneal sub-basal nerve plexus. Hydrogel CL wear might be involved in the recruitment of dendritic cells into the cornea, being a possible origin its lower oxygen permeability compared to silicone hydrogel materials. Future studies are required to confirm these results.

Purpose: To assess the consecutive implementation of habitual contact lens discomfort (CLD) management strategies: lid hygiene, daily disposable CL (DDCL) fitting, and artificial tear (AT) supplementation. Methods: Contact lens (CL) wearers with CLD symptoms (CLDEQ-8 ≥12 points) were included in the study. Subjects with Meibomian gland dysfunction (MGD) were instructed to perform lid hygiene. All participants were fitted with a DDCL (delefilcon A) and evaluated 1 month later. After, half of them were randomly assigned to use AT (Povidone-2%) at least three times/day, and all participants were evaluated 1 month later. Tests performed were: lower tear meniscus area (LTMA), bulbar, limbal, and tarsal hyperemia, noninvasive tear break-up time (NITBUT), and corneal and conjunctival staining. Weighted combined clinical scores (CS) were created to analyze signs. Changes in symptoms (CLDEQ-8) and CS were analyzed using linear mixed models. Results: Forty-two subjects (mean age: 23.2±4.9 years) completed the study. Two CS were created, CS 1 was composed of bulbar, limbal, and tarsal hyperemia and corneal staining, and CS 2 by NITBUT, LTMA, and conjunctival staining. CLDEQ-8 was reduced after lid hygiene (mean: −2.73±2.13; P=0.012) and DDCL use (mean: −10.1±3.54; P<0.01), but not after AT use (P=0.62). CS 1 did not change after any intervention. CS-2 was higher (P=0.04) in DGM subjects after lid hygiene, it decreased (P=0.04) after DDCL use. Conclusions: Lid hygiene is effective for reducing CLD symptoms in MGD patients. Refitting subjects with delefilcon A is an effective intervention for CLD to reduce symptoms and achieve a healthier ocular surface. Simultaneous administration of AT did not further improve CLD.

Purpose: To analyze the effects of contact lens (CL) wear, time of the day, and CL discomfort (CLD) on clinical signs, tear inflammatory mediators and substance P. Methods: Thirty symptomatic and 30 asymptomatic CL wearers attended two visits (morning and afternoon) on two days (non-CL and CL wearing days). Comfort, meniscus area, noninvasive breakup time (NIBUT), tear collection, hyperemia, lid parallel conjunctival folds, fluorescein staining, and sensitivity were performed. The tear levels of 23 inflammatory mediators and substance P were measured. Results: Comfort, meniscus area, NIBUT, and MMP-9 were lower while conjunctival staining and EGF higher (p ≤ 0.015) on the CL wearing day. Comfort, IL-8/CXCL8, and VEGF were lower while EGF, IP-10/CXCL10, and MCP-1/CCL2 higher (p ≤ 0.047) in the afternoon. Comfort was lower and substance P higher (p ≤ 0.006) in symptomatic wearers. Conclusion: Substance P may be implicated in CLD etiology; its role and potential application as a biomarker should be further studied.