Abstract
Purpose:
To evaluate chronic allergic inflammation of the eye at the cellular level following the standard micro-Conjunctival Allergen Challenge (micro-CAC) using confocal imaging.
Methods:
Sixteen (16) subjects allergic to dust mites were enrolled in a 3 visit study. Subjects were titrated to their sensitivity of dust mite allergen at Visit 1. At Visit 2 the subjects received two sessions of micro-CAC 8 hours apart. Assessments included conjunctival injections, chemosis, ocular itching, eyelid swelling, as well as leukocyte infiltration of the vasculature. The Ora Calibra scale of confocal microscopy grades on the density, adherence and extravasation of leukocytes in conjunctiva vessels. Subjects were assessed at Visit 3 (16 hours post Visit 2) to explore the level of inflammation that persisted. This was followed by another challenge again at Visit 3B (19 hours post V2) to examine the effects of an allergic challenge on a system already in a state of inflammation.
Results:
Following the first two micro-CAC challenge sessions, injection increased to 2.5 (p<0.001), chemosis increased to 1.3 (p<0.001), itching increased to 2.9 (p<0.001), eyelid swelling increased to 1.4 (p<0.001) and confocal infiltration of cells increased to 3.1 (p<0.001). At visit 3A, injection was 1.7 (p<0.001), chemosis was 0.69 (p<0.001), itching was 0.25 (p<0.018), eyelid swelling was 0.5 (p<0.012), and confocal infiltration of cells was 2.13 (p<0.001). Following the third session of micro-CAC at Visit 3B, chemosis increased to 1.64 (p<0.037), injection to 2.8 (p<0.001), and itching to 3.24 (p<0.060) from Visit 2B.
Conclusions:
The level of inflammation created with this model produced chronic lingering effects on signs and symptoms of allergic conjunctivitis at16 hours post CAC. The increase in infiltration of leukocytes at the vasculature level is not only clear following the micro-CAC challenges but is also present at 16 hour post challenge (Visit 3A). Furthermore, the induced state of chronic inflammation following another micro-CAC (Visit 3B) causes an increase in reaction compared to the acute challenge. Confocal imaging and grading of leukocytes in real time allows us to track and the course of chronic inflammation while correlating to signs and symptoms. Currently the anti-inflammatory effect at the cellular level of a topical corticosteroid is being investigated.
Keywords: 550 imaging/image analysis: clinical •
557 inflammation •
475 conjunctivitis