Ocular thermography measurements can predict discomfort in soft contact lens wearers
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Key takeaways:
- Noninvasive tear breakup time and thermal cooling rate were identified as significant predictors of contact lens-induced dry eye.
- Cooling rate was consistently higher in the symptomatic group.
Thermal cooling rate and noninvasive tear breakup time significantly predicted contact lens-induced dry eye, according to a study published in Optometry and Vision Science.
These findings suggest that ocular thermography may be an effective tool for measuring contact lens discomfort in patients, according to researchers.
“Contact lens discomfort, particularly toward the end of the day, affects up to half of contact lens wearers with variable frequency and magnitude. This issue represents the primary cause of discontinuation from contact lens wear,” Maryam Moghadas, PhD, data scientist and R&D engineer at the Menicon R&D Innovation Center, and colleagues wrote.
However, clinical tests to assess ocular discomfort can be “invasive or subjective,” they wrote. Ocular thermography presents a noninvasive and objective method to perform this assessment.
Moghadas and colleagues sought to investigate the associations between contact lens-induced dry eye symptoms and ocular thermography clinical measurements in habitual symptomatic and asymptomatic soft contact lens wearers.
The prospective, exploratory single-center study included 40 habitual contact lens wearers (women, n = 27) from the optometry department of University of Applied Sciences in Olten, Switzerland. They were split into two groups (n = 20 per group), which were matched by age and gender, based on their responses to the eight-item Contact Lens Discomfort Questionnaire: an asymptomatic group (score 8; mean age, 28.6 ± 8.5 years) and a symptomatic group (score 14; mean age, 27.2 ± 6.4 years).
Moghadas and colleagues measured Ocular Surface Disease Index questionnaire score, noninvasive TBUT, bulbar conjunctival hyperemia, corneal staining and thermal cooling rate at visit 1 (contacts in and after removal) and at baseline/visit 2 after a 2-week washout period with no contact lens wear. They calculated the thermal cooling rate in the central and lower cornea during natural blinking (30 seconds) and sustained eye opening (10 seconds).
Results showed the OSDI score was significantly higher in the symptomatic group while they were wearing contacts (P < .001) and at baseline (P = .001).
The cooling rate also was consistently significantly higher in the symptomatic group, in both the lower cornea during sustained eye opening with contact lenses in (P = .013) and in the central cornea during natural blinking immediately after contact lens removal (P = .045).
At baseline, dry eye symptoms (30 sec: r = 0.5, P = .03; 10 sec: r = 0.63, P = .005) and noninvasive TBUT (30 sec: r = 0.6, P =.005; 10 sec: r = 0.55, P = .018) significantly correlated with cooling rate in the central corneal region in the symptomatic group.
Finally, the researchers identified cooling rate in the cornea for a 10-second duration and noninvasive TBUT (P < .0001 for both) as significant predictor variables for dry eye symptoms, based on OSDI score, at baseline.
“The automated, noninvasive, noncontact and quantitative nature of ocular thermography may suggest it as a viable method to indirectly measure evaporation rate, assisting screening for the diagnosis of dry eye symptoms and, consequently, discomfort in contact lens wear,” Moghadas and colleagues wrote.
Future research should include a comprehensive model that analyzes the entire cooling process between blinks and investigate the relationship between blink frequency and thermal cooling rate, they added.
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