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Maria J. Tort, Richard Ornberg, Bruno Lay, Ronan Danno, Fiona Soong, Natasha Camuso, Anne Marie Salapatek; Development of an Objective Assessment of Conjunctival Hyperemia Elicited via Conjunctival Allergen Provocation Testing (CAPT) and Environmental Exposure Chamber (EEC) Testing. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4017.
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Conjunctival hyperemia is an important endpoint in ophthalmic clinical research. Most methods for assessing hyperemia are highly subjective and variable across sites. This study describes an imaging method and software system that objectively and automatically quantifies conjunctival hyperemia elicited by ocular allergen exposure.
Thirteen subjects with a history of allergic conjunctivitis were exposed to ragweed allergen via conjunctival allergen provocation testing (CAPT) and environmental exposure chamber (EEC) testing. Itching was assessed on diary cards by subjects. Hyperemia was assessed by clinicians, using standardized 9-point scales from 0 (none) to 4 (extremely severe). Slit-lamp images of conjunctiva were captured. The Imaging System for Ocular Surface (ISOS; Novartis) was developed as a software suite for automated image analysis of conjunctival blood vessel morphology.
With CAPT, hyperemia transiently rose with a peak at 30 minutes post exposure. With EEC, hyperemia increased gradually, with a maximum at the last time point (180 minutes). Itching scores paralleled the hyperemia scores. Automated image measurements by ISOS provided a variety of vessel morphological measures that were not evident to a clinical observer, including, vessel diameter, total vessel length, vessel density (vessel area/total area, VD), tortuosity and bifurcation points. Vessel density closely correlated with manual grading captured by trained clinicians for hyperemia assessment. After CAPT instillation, mean VD transiently rose in the initial time points (5, 10 and 20 minutes after exposure) and decreased after 30 min. With EEC, the mean VD increase was gradual, appearing to still be high at the end of the observation period.
Results from this pilot study indicated that the ISOS imaging method and image analysis suite may objectively measure parameters of conjunctival hyperemia resulting from either CAPT or EEC testing.
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