Ocular thermography and clinical measurements in symptomatic and asymptomatic soft contact lens wearers

SIGNIFICANCE:Symptoms of dryness and discomfort are the main reasons for contact lens dropout. Clinical tests for this purpose are invasive or subjective. Ocular thermography may help to assess the ocular discomfort and dryness in a noninvasive and objective manner. PURPOSE: This study aimed to investigate the relationship of ocular thermography with clinical measurements in habitual symptomatic and asymptomatic soft contact lens wearers. METHODS: Forty habitual contact lens wearers were evaluated in two age- and gender-matched asymptomatic and symptomatic groups (Contact Lens Discomfort Questionnaire scores <= 8 and >= 14, respectively). Clinical measurements took place during visit 1 (with contact lens in situ and after contact lens removal) and at baseline after a 2-week washout period (visit 2). The Ocular Surface Disease Index (OSDI) questionnaire, noninvasive tear breakup time, bulbar conjunctival hyperemia, and corneal staining were assessed. Thermal cooling rate was computed in the central and lower cornea during natural blinking (30 s) and sustained eye opening (10 s). RESULTS: Dry eye symptoms (OSDI score) were significantly higher in the symptomatic group during contact lens wear (p<0.001) and at baseline (p = 0.001). Thermal cooling rate was significantly higher in the symptomatic group in the lower cornea (10 s, p=0.013) with the contact lens in situ and in the central cornea (30 s, p=0.045) after contact lens removal. At baseline, dry eye symptoms (OSDI score) significantly correlated with cooling rate in the central cornea region for the symptomatic group (30 s: r = -0.5, p=0.03; 10 s: r = -0.63, p=0.005). Noninvasive tear breakup time correlated with cooling rate in the central cornea region at baseline in the symptomatic group (30 s, r = 0.6, p=0.005; 10 s, r = 0.55, p=0.018). Cooling rate in the central cornea region (10-s duration, p<0.0001) and noninvasive tear breakup time (p<0.0001) were identified as significant predictor variables for dry eye symptoms at baseline. CONCLUSIONS: Noninvasive tear breakup time and thermal cooling rate were identified as significant predictor variables for contact lens-induced dry eye. These findings may suggest the potential for the additional application of ocular thermography in the evaluation of contact lens discomfort.