Diagnostic impression cytology: a simple technique for the diagnosis of external eye disease

Abstract

The technique of impression cytology was used for cytologic examination of conjunctival samples from 128 patients with a variety of external eye diseases. The method of sample collection and the staining procedure are described. Microscopic examination showed 62 cases with allergic conjunctivitis, 23 with bacterial or viral infection, 26 cases with changes typical of dry eye and 17 cases with non-specific chronic inflammation. The cytologic features and numerous applications of impression cytology are discussed.

Objective assessment of conjunctival squamous metaplasia by measures of cell and nucleus dimensions

“…Some of the reports on CIC from dry eye patients also illustrate elongated cells or even spindle shaped cells 13, 18, 21, 32, 40, 53, 60. In contrast, other images of cells assigned grade 3 (as with the present studies) simply illustrate these cells to be apparently enlarged in overall size without any substantial elongation 9, 15, 17, 18, 22, 23, 27, 33, 48, 49, 61, 62. Part of the goal of the present studies was to objectively assess even slightly enlarged cells to see if a statistically significant change in cell shape could be found.…”

“…These may be different according to the etiology of the ocular surface disease (and why almost no pyknotic nuclei have been seen in the samples analyzed in the present study). However, there are also other published images that, assuming the final magnifications were at least similar, indicate that few if any of the conjunctival cells assigned a grade 3 for squamous metaplasia have pyknotic nuclei and that nuclei in these enlarged cells can be the same size or even slightly larger than normal 9, 11–14, 17, 21, 25, 28, 34, 44, 49, 56–59. Such metaplastic cells have been reported for a wide range of clinical conditions, but it needs to be established whether this presumed end stage of cell alteration is actually any different for different ocular surface diseases.…”

“…Cytological changes associated with squamous neoplasia have some features similar to squamous metaplasia 7, 8. CIC has been widely considered as a possible means of assessing the general health of the conjunctival surface as well as providing a possible means to detect pathological changes 5–10…”

Assessment of agreement for assignment of a normal grade to human conjunctival impression cytology samples

“…Figure 1a). 3–5 The present analyses indicate that more quantitative studies are needed to define a normal cell, as well as those given abnormal grades.…”

“…Conjunctival impression cytology (CIC) allows for sampling of cells of the bulbar conjunctiva without the need for surgical intervention, to assess the general health of the conjunctival surface. [1][2][3][4][5] A small piece of a filter membrane is pressed onto the bulbar conjunctival surface to remove a layer or multiple layers of cells that can then be fixed and stained. 1 This provides an unambiguous coronal (or en face) perspective of the cells as arranged in situ.…”