Conjunctival impression cytology: feasibility of a field trial to detect subclinical vitamin A deficiency.

Two hundred and thirty-six Guatemalan children aged 2-14 y were examined for subclinical vitamin A deficiency by use of conjunctival impression cytology (CIC). The feasibility of the technique and quality of a modified touch procedure were assessed. Neither lid speculum nor physical restraint in the form of a papoose board was used. The CIC technique was easily performed on children aged greater than 3 y but was more difficult among those less than or equal to 3 y. Laboratory processing of specimens is uncomplicated but interpretation may be problematic and requires clearly defined criteria of normal and abnormal cytology as well as careful standardization of readers.