Assessment of changes in eye redness by a photographic method and the relation to sensory eye irritation

The purpose of the present study was to evaluate the relation between photographically assessed changes in eye redness and sensory eye irritation in 17 patients suffering from hayfever, provoked by increasing doses of birch pollen in the eye. Pre- and post-exposure diapositives were compared in a randomized and double blind design by a panel of five members. By evaluating the photographs we found a high reproducibility between panel members and for repeated evaluation by the individual panel member. Furthermore, we found that the photographic method was more sensitive for measurements of changes in eye redness than the observations normally performed during such conjunctival provocation tests. The correlations of the objective findings with the symptoms reported were good at high pollen doses, but at lower doses of birch pollen (about half the effective dose) a decreased eye redness was observed. We found that sensory irritation (often expressed as dryness) measured simultaneously by questionnaires, in general occurred before any increased eye redness. The study indicates that photographic measurement of eye redness is reproducible, sensitive, unbiased and therefore a useful tool in environmental studies. Furthermore we demonstrated that the relation between eye redness and eye irritation is interestingly biphasic and may need further clarification.