Among tests used to evaluate ocular status and diagnose dry eye disease (DED), impression cytology is considered practical and minimally invasive. However, it is used less often than mainstays like Schirmer strips, fluorescein staining and tear break-up time.

Determined to learn more, a team of researchers from Saudi Arabia conducted a study to characterize ocular surface symptoms typical of DED, study the pattern of DED in various systemic diseases, assess whether impression cytology samples can be used to define conjunctival surface changes, describe changes in conjunctival cells and compare the sensitivity of impression cytology with other diagnostic tests.

This cross-sectional study evaluated 100 participants with symptoms of DED. The team obtained patient history—including systemic disease, occupation and drug intake—and performed Schirmer’s testing, tear break-up time testing, lissamine green staining and conjunctival impression cytology.

When performed individually, the researchers found that clinical tests have limited diagnostic value. Impression cytology, however, showed the highest sensitivity, they note.

The study concludes that impression cytology is an “ideal method of investigating ocular surface disorders when diagnosis is not clinically obvious or when clinical diagnosis needs substantiation.” The team recommends major ophthalmic centers develop and introduce this technique into routine clinical practice.

Al Wadani FA, Wahhab KMA, Nambiar R, et al. Reliability and utility of impression cytology in the diagnosis of dry eye. Niger J Ophthalmol. December 13, 2016. [Epub ahead of print].