Corneal surface temperature dynamics with lipid vs non-lipid artificial tears during sustained eye opening: a crossover study.

PURPOSE: To evaluate the impact of lipid-containing versus lipid-deficient artificial tears on dynamic corneal surface temperature (CST) decline during sustained eye opening.

METHODS

Fifteen healthy volunteers aged 20-40 years were examined under standardized room conditions (22-24 °C, 45-50 % humidity). Two hyaluronic acid (HA)-based tear supplements-Thealoz Duo (TD; 3 % trehalose, 0.15 % HA) and Artelac Advanced (AA; 0.2 % HA)-and their lipid-containing counterparts-Thealipid (TL) and Artelac Complete (AC)-were instilled in right eyes on four separate visits after an initial 5-minute acclimatization. Following eyedrop instillation, subjects underwent a second round of 5-minute acclimatization period, after which they were instructed to maintain sustained eye opening for 15 s during thermal image acquisition. CST was recorded within the 3 mm central cornea using a high-sensitivity infrared camera (FLIR A8200sc). Changes were compared with contralateral control eyes using analysis of covariance, with Schirmer and tear break-up time (TBUT) included as covariates.

RESULTS

Lipid-deficient formulations accelerated CST decline, with slope differences of -0.06 °C/15 s for AA and -0.12 °C/15 s for TD (both p < 0.001). In contrast, lipid-containing formulations better preserved CST, with minimal changes (0.05 °C/15 s for TL; -0.03 °C/15 s for AC, both p < 0.001). Time-segmented analyses showed the steepest CST drop occurred within the first 5 s post-blink, particularly with AA and TD (p < 0.001), whereas TL maintained stable CST relative to controls. Neither Schirmer nor TBUT influenced CST dynamics.

CONCLUSION

Lipid-containing artificial tears maintained CST stability better than lipid-deficient formulations. The decline in CST during interblink periods may be more pronounced in dry eye disease, particularly with meibomian gland dysfunction, and during prolonged screen use where evaporation is increased.