Evaluation of allergic conjunctivitis by thermography

To evaluate ocular surface temperature in assessing the efficacy of anti-allergic eye drops.

Thirteen asymptomatic patients (24.7 ± 2.8 years) with proven seasonal allergic conjunctivitis due to cedar pollen were studied. A 0.025% levocabastine ophthalmic suspension was instilled in one eye (levocabastine eye) and artificial tears in the other eye (artificial tear eye) in a masked fashion 10 min prior to a conjunctival allergen challenge (CAC). Then, a drop of cedar pollen solution was dropped into the conjunctival sac to induce the allergic reaction. The surface temperature of the inferior bulbar conjunctiva was measured before and 30 min after the CAC with a newly developed non-contact ocular surface thermographer (OST). The degree of conjunctival injection and chemosis was also determined by slit-lamp biomicroscopy. The changes in the symptoms were evaluated by a questionnaire.

After the CAC, the temperature increased by 0.67 ± 0.10°C in the artificial tear eyes but by only 0.21 ± 0.06°C in the levocabastine eyes (p < 0.05). The score for conjunctival injection was 1.38 ± 0.24 and the chemosis score was 0.85 ± 0.25 for the artificial tear eyes and 0.62 ± 0.27 and 0.08 ± 0.08 in the levocabastine eyes (p < 0.01). The temperature increase was significantly correlated with the conjunctival injection scores (r = 0.63; p < 0.001).

The significant correlation of the conjunctival surface temperature with the severity of the conjunctival allergic reaction indicates that the temperature measured by the OST can be used to objectively evaluate the efficacy of topical anti-allergic agents.