Indian Journal of Ophthalmology

: 1991  |  Volume : 39  |  Issue : 1  |  Page : 22--24

Conjunctival impression cytology in dry eye states

Madhavati Reddy, P Ranga Reddy, SC Reddy 
 Sarojini Devi Eye Hospital, Hyderabad-500 028, India

Correspondence Address:
S C Reddy
Sarojini Devi Eye Hospital, Hyderabad-500 028


Impression cytology technique was used to study the cytological changes of in 30 patients with various diseases (Xerophthalmia, Steven-Johnson«SQ»s syndrome, trachoma, alkali burns, kerato conjunctivitis sicca) resulting in dry eye syndrome. The main features of impression cytology were squamous metaplasia of epithelial cells and altered goblet cell density. The comparison between conjunctival biopsy findings and impression cytology confirm that impression cytology provides the same information as that of biopsy. Hence, the authors advocate that this non-invasive simple technique can replace conjunctival biopsy in confirmation of diagnosis in dry eye syndrome.

How to cite this article:
Reddy M, Reddy P R, Reddy S C. Conjunctival impression cytology in dry eye states.Indian J Ophthalmol 1991;39:22-24

How to cite this URL:
Reddy M, Reddy P R, Reddy S C. Conjunctival impression cytology in dry eye states. Indian J Ophthalmol [serial online] 1991 [cited 2022 Dec 6 ];39:22-24
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Alteration in any component of the tear film will result in its dysfunction, giving rise to typical symptoms and signs of dry eye syndrome. The clinical diagnosis of dry eye is based on slit lamp examination, Schirmer's test, tear film break up time and Rose Bengal staining. The his­topathological features are conventionally studied by conjunctival biopsy. This procedure being invasive is not done routinely. Recently a filter paper technique utilising millipore cellulose acetate paper has been developed, to obtain the conjunctival impressions and study the cellular morphology [1]. Several studies [2],[3] have been con­ducted to study the epithelial changes occurring in ocular surface disorders. The technique has also been used to detect subclinical deficiency of vitamin A [4],[5] and was found to be more effective than the existing methods of diagnosis.

In the present study, this non-invasive simple technique has been used to examine the conjunctival changes in dry eye syndrome. An attempt was made to correlate the impression cytology findings with that of biopsy features.


A total of thirty patients with symptoms of dry eye were selected from the out-patient department. The patients included 15 males and 15 females, ranging from 5 to 45 years age. Ten normal subjects in the same age group served as controls.

After obtaining a complete history, a thorough slit lamp examination of the tear film conjunctiva and cornea was performed. In addition. Schirmer test, tear film break up time and Rose Bengal staining were done. Schirmer test was done using Whatman No. 41. filter paper strips (5 x 35 mm) after anaesthetizing the conjunctival sac with 4% xylocaine. Tear film break up time was assessed using freshly prepared 1 % fluorescein solution. Rose Bengal staining was done using 1 % solution and the pattern of staining noted.

Conjunctival impressions were obtained using millipore cellulose acetate paper strips (3 x 10 mm size with a diagonal edge). The eyes were topically anaesthetized with 4% xylocaine drops. A speculum was inserted and the lacrimal lake at the inner canthus was dried with a swab. A blunt smooth edged forceps was used to grasp the filter paper strip at one end and the paper was applied on the temporal bulbar conjunctiva. A smooth glass rod held in the other hand was used to press the paper gently. The paper strip was then removed with a peeling motion after 2-3 seconds. The strips were dropped into a bottle containing the fixative solution, (ethyl alcohol, formaldehyde and glacial acetic acid in 20:1:1 volume ratio). The strips were transferred to the laboratory for staining. The staining procedure followed is given in [Table 1]. The slides were examined under the light microscope.

Conjunctival biopsies were taken in the same patients from the inferotemporal bulbar conjunctiva and specimens processed for histopathological examination using haematoxylin and eosin stains.

Impression cytology specimens were graded as normal or abnormal based on epithelial cell morphology and goblet cell density. Normal impressions from the con­trols showed sheets of polygonal epithelial cells, inter­spersed with plenty of goblet cells [Figure 1].

The abnormal impressions showed squamous metaplasia of the epithelial ce1's and altered goblet cell densities [Figure 2]. They were graded into 3 stages based on the following criteria : morphological changes of the epithelial cells, cohesion of cells, nucleus/cytoplasmic ratio and keratinization.


(i) Mild metaplasia: The cells are slightly enlarged, polygonal in shape and are separated from each other. Nucleus/cytoplasmic ratio ranged from 1:2 to 1:4. There is no keratinization.

(ii) Moderate metaplasia: The cells are enlarged, flat­tened and the nucleus/cytoplasmic ratio is 1:6. There is mild to moderate keratinization.

(iii) Marked metaplasia: The cells are thin and flat with edges folding in. The nucleus is small and pyknotic. The nucleus/cytoplasmic ratio is 1:8. There is ad­vanced keratinization. Goblet cells were described as being normal, decreased in number or totally absent.

Conjunctival biopsies were examined under the light microscope to assess the degree of squamous metaplasia of the epithelium and goblet cell density.


The ocular disorders resulting in dry eye syndrome, the Schirmer test values and the tear film break up times are shown in [Table 2]. In alkali burns the 2 acute cases had values of 10 and 25 mm. Rest of the cases showed low values. Tear film break up time was found to be abnor­mal in all the cases.

The impression cytology specimens were graded and classified according to our staging method. The findings in various dry eye status are given in [Table 3].

Tseng [2] classified squamous metaplasia into 6 stages using Gill's modified Papanicoloau's stain. This clas­sification is based on goblet cell density, morphological changes in the nucleus, nucleus/cytoplasm ratio and meta chromic changes of cytoplasmic color. We could not follow this staging because certain dry eye cases showed advanced squamous metaplasia of the epithelium in the presence of goblet cells. This was observed in the late stages of alkali burns, kerato con­junctivitis sicca and congenital lid coloboma. Further studies are needed covering larger groups to confirm these observations and elucidate the exact relationship between the epithelial metaplasia and goblet cell den­sity.

The conjunctival biopsy findings correlated very well with impression cytology features both in normal sub­jects and dry eye states. Maskin et a1 [6] examined impres­sion acquired cells by electron microscopy and the results were found to be similar to those from excision acquired cells.

The impression cytology technique has also been used as a prognostic indicator in evaluating efficacy of therapeutic measures in different dry eye syndromes [7] [8].Topical retinoids were used and reversal of cytological changes were demonstrated by impression cytology. This technique has also been used for the debridement of herpes simplex dendritic keratitis [9].

The technique is simple, non-invasive and can be repeated a number of times in an individual. Thus it can serve as a diagnostic as well as prognostic parameter in assessing a dry eye state.


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