Impression cytology detects subclinical vitamin A deficiency.

The vitamin A status of 16 children with normal eyes and liver disease was evaluated by plasma retinol concentration and by liver vitamin A concentration or iv relative-dose-response test. Conjunctival impression cytology was performed on each child. All children with normal vitamin A status had normal conjunctival impression cytology. All children with abnormal vitamin A status had abnormal conjunctival impression cytology despite their seemingly normal clinical ocular examination. These results suggest that impression cytology can identify individuals with physiologically significant, preclinical vitamin A deficiency.