Reliability and Utility of Impression Cytology in the Diagnosis of Dry Eye
Introduction: Dry eye disease is a multifactorial disease of the tears and ocular surface that can result in ocular discomfort and visual impairment. There are numerous tests to evaluate the ocular status in dry eye disease. Among the different tests for diagnosing dry eyes, Impression Cytology is considered a practical and minimally invasive investigation. Objective: The aim of this study was to characterize ocular surface symptoms typical of dry eyes, study pattern of dry eye in various systemic diseases, assess whether impression cytology samples could be used to define conjunctival surface changes and describe changes in conjunctival cells. We also aimed to compare the sensitivity of impression cytology with other diagnostic tests. Methods: A cross sectional study was conducted among 100 patients with symptoms of dry eye. After eliciting a complete history which included any systemic disease, occupation and drug intake these patients were subjected to various tests like Schirmers test, Tear Break Up Time (TBUT), Lissamine green staining and Conjunctival impression cytology. Results: All clinical tests have limited diagnostic value if performed individually, but impression cytology showed the highest sensitivity. Conclusion: It is recommended that impression cytology is an ideal method of investigating ocular surface disorders when diagnosis is not clinically obvious or when clinical diagnosis needs substantiation. It is recommended that major ophthalmic centers should develop and introduce this technique into routine clinical practice.
Key words: Dry eye, impression cytology, lissamine green, tear break up time