RESUMO
PURPOSE: To compare the effects on ocular temperature and tear film parameters following a single application of a latent heat eyelid warming device at a range of temperature settings. METHODS: Fifteen subjects were enrolled in a prospective, investigator-masked, randomised, cross-over trial. On separate days, participants were randomised to 10-minute application of a research latent heat device (Laboratoires Théa) at device temperature settings of 45⯰C, 50⯰C and 55⯰C. Outer eyelid and corneal temperatures, tear film lipid layer grade, and non-invasive tear film breakup time (NIBUT) were measured at baseline and immediately after 10â¯min of device application. RESULTS: Baseline measurements did not differ between treatment groups (all pâ¯>â¯0.05). Ocular temperatures, lipid layer grade and non-invasive tear film stability rose significantly following device application in all treatment groups (all pâ¯<â¯0.05). The 55⯰C setting effected a mean ocular surface temperature rise in the order of +4⯰C from baseline, which was 1.46 and 1.26 times greater than at the 45⯰C and 50⯰C temperature settings, respectively (all pâ¯<â¯0.05). Similarly, improvements in mean non-invasive tear film stability from baseline in the order of +7â¯s were observed, which were 2.43 and 1.66 times greater than those at the lower temperature settings of 45⯰C and 50⯰C, respectively (all pâ¯<â¯0.05). CONCLUSIONS: At all temperature settings, the latent heat device resulted in clinically and statistically significant increases in ocular temperature, lipid layer grade, and non-invasive tear film stability. However, the 55⯰C setting proved to be most effective at raising ocular temperature (in the order of +4⯰C from baseline) and improving tear film stability.