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Updated: Jun 13, 2026
Impression Cytology of the Lid Wiper Area
Published on: August 9, 2016
Polycarbonate membrane impression cytology: evidence for fluorescein staining in normal and dry eye corneas
Sumeer Thinda1, Puneeta K Sikh, Lawrence M Hopp
1Jules Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
Background/Aims:
Corneal impression cytology is usually performed with mixed cellulose ester membranes and a limited array of stains. A method using polycarbonate membrane air-dried preparations led to the discovery of fluorescein staining in cells from patients with and without dry eye disease and a membrane-induced defect that was not due to cell removal.
Methods:
Impressions after fluorescein installation were performed using polycarbonate and mixed cellulose ester membranes with rapid staining protocols for Diff-Quick as well as haematoxylin and eosin stains. Prior to staining the air-dried material was examined for fluorescence.
Results:
Epithelia of both normal and dry eye corneas retained fluorescence from clinical instillation of fluorescein. Corneal defects created by the polycarbonate membrane could not be explained by membrane-induced cell removal. After rapid staining, polycarbonate membranes revealed less background, dissolved easily prior to coverslip application, but showed lower cellular yield compared with the mixed cellulose membranes.
Conclusion:
Polycarbonate membrane impression cytology enables immediate assessment with rapid stains. Topically applied fluorescein penetrates corneal epithelial cells in both normal and dry eye patients. Cells fluoresce on the cytology membranes. The impression-induced defect on the cornea is not due to cell stripping and may represent removal of mucins.
Insights
Polycarbonate membrane impression cytology reveals fluorescein staining in corneal cells of patients with and without dry eye disease. This method offers rapid assessment and identifies a novel corneal defect not caused by cell removal.
Area of Science:
- Ophthalmology
- Cell Biology
- Medical Diagnostics
Background:
- Corneal impression cytology traditionally uses mixed cellulose ester membranes and limited stains.
- A novel method employing polycarbonate membranes and air-dried preparations was investigated.
Observation:
- Fluorescein staining was observed in corneal cells from both dry eye and normal patients.
- A membrane-induced corneal defect was noted, distinct from cell removal.
Findings:
- Polycarbonate membranes allow for immediate assessment with rapid stains like Diff-Quick and hematoxylin and eosin.
- Corneal epithelial cells retain fluorescein after topical application, fluorescing on cytology membranes.
- The observed corneal defect is not due to cell stripping but may involve mucin removal.
Implications:
- This technique facilitates rapid, in-situ analysis of corneal epithelial cells.
- Topical fluorescein penetration into corneal cells is confirmed in both healthy and dry eye conditions.
- The findings suggest a new understanding of corneal surface interactions during cytological sampling.
