ORIGINAL ARTICLE
Year : 2002 | Volume
: 50 | Issue : 4 | Page : 301--306
Conjunctival impression cytology in contact lens wearers.
P Simon, Saramma G Jaison, Sudesh K Chopra, S Jacob
Department of Ophthalmology, Christian Medical College and Hospital, Ludhiana 141 008, Punjab, India
Correspondence Address:
P Simon
Department of Ophthalmology, Christian Medical College and Hospital, Ludhiana 141 008, Punjab
India
Abstract
PURPOSE: To evaluate the cytological changes in conjunctiva following regular contact lens wear and to determine the correlation, if any, between severity of cytological alteration and symptoms related to contact lens wear. METHODS: One hundred eyes (50 normal asymptomatic subjects) who served as a control group were studied by conjunctival impression cytology (CIC). These subjects were fitted with rigid gas permeable (RGP) or soft contact lenses and were followed up at the end of 3 and 6 months. At each follow-up visit the CIC was repeated. A filter paper with the impression specimen was stained with periodic acid schiff (PAS) and haematoxylin stain to study goblet cell loss. Papanicolaou stain was done to study squamous metaplasia. The cytological changes were graded using the system described by Natadisastra et al. RESULTS: Severity of cytological changes increased with the duration of contact lens wear (P = 0.00001). At the end of 6 months, 60% of symptomatic eyes wearing soft contact lens and RGP lens showed abnormal CIC changes. None of the asymptomatic RGP contact lens wearing eyes showed abnormal CIC changes whereas 33.4% of the asymptomatic soft contact lens wearing eyes showed abnormal CIC changes (P = 0.033). Epithelial changes occurred within 3-6 months of contact lens fitting. CONCLUSION: Severity of cytological changes increased with duration of lens wear (P = 0.00001). Prevalence and severity of cytological alteration is more in symptomatic contact lens wearers. Soft contact lens wearers although asymptomatic showed severe CIC changes.
How to cite this article:
Simon P, Jaison SG, Chopra SK, Jacob S. Conjunctival impression cytology in contact lens wearers. Indian J Ophthalmol 2002;50:301-306
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How to cite this URL:
Simon P, Jaison SG, Chopra SK, Jacob S. Conjunctival impression cytology in contact lens wearers. Indian J Ophthalmol [serial online] 2002 [cited 2023 Nov 28 ];50:301-306
Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?2002/50/4/301/14762 |
Full Text
The human tear film is rather unstable, but it is regenerated by frequent blinking. When a contact lens is placed on the eye, the lens alters the structure of the tear film and rate of evaporation. These changes affect the ocular surface as well as the contact lens itself.[1] Conjunctival epithelial changes have been reported in both symptomatic and asymptomatic lens wearers. The main changes are squamous metaplasia, decrease in goblet cell density and presence of abnormal chromatin material in epithelial cell nuclei.[2][3][4][5][6] Egbert et al introduced conjunctival impression cytology (CIC), a simple non-surgical technique to study the cytologic response of conjunctiva. It is a non-invasive and painless technique.[7] It can be used safely in contact lens wearers and does not necessitate any cessation of lens wear unlike in excision biopsy.[2]
The purpose of this study was to evaluate the conjunctival surface changes in contact lens wearers using CIC and to find any correlation between the severity of cytological alteration and symptoms related to contact lens wear.
Materials and Methods
One hundred normal asymptomatic eyes of 50 participants were studied by CIC before contact lens fitting. A baseline conjunctival surface evaluation was done by CIC before contact lens fitting. This was taken as control. Participants were then fitted with rigid gas permeable (RGP) or soft contact lenses on a daily wear basis. Subjects with any past history of ocular surface disorders, ocular surgery, ocular trauma, longterm use of topical medication and those with evidence of ocular surface disorder on slitlamp examination were excluded from the study.
Participants were requested to return for follow-up at the end of 3 and 6 months. One week before the follow-up date they were contacted by mail or by telephone. Fallout of participants was due to several reasons including contact lens intolerance, non-compliance, non-availability during the study period, and occasional use. Participants on follow-up were divided into symptomatic and asymptomatic groups based on presence/absence of symptoms like pain, discharge, foreign body sensation, itching, and redness.
Sixty-four eyes of 32 participants - 38 RGP and 26 soft lens-wearing eyes-were studied at the end of 3 months. Fifty-six eyes of 28 participants - 34 RGP and 22 soft lens-wearing eyes-were studied at the end of 6 months.
Technique
Cellulose acetate paper (HAWP 01300) was cut into small squares of 5 x 5 mm. The conjunctiva was anaesthetised by topical 4% xylocaine and the filter paper was applied to the superior bulbar conjunctiva 2 mm away from the limbus, using forceps. Gentle pressure was applied with the blunt end of the forceps for 3-5 seconds and then the filter paper was removed with a peeling motion. Two such samples were taken, one from the 11 o'clock and the other from the 1 o'clock position. One filter paper was then fixed in a solution of 70% ethyl alcohol, 37% formaldehyde and glacial acetic acid in a recommended standard volume ratio 20:1:1 for 10 minutes and the other filter paper in 95% ethyl alcohol. The filter paper fixed in 95% ethyl alcohol was stained with Papanicolaou stain and the other with PAS and haematoxylin stain. Both filter papers were then cleared in xylene, mounted and viewed under the light microscope. Morphologic changes in epithelial cells, characteristics of nuclear chromatin and goblet cell loss were noted. The examiners were masked to the nature of these slides and the entire slide was examined to determine the nature of the cytological changes.
Staging of conjunctival squamous metaplasia was done according to the systems described by Natadisastra et al[8] as given below. CIC was considered normal if any area of the specimen demonstrated a substantial proportion of normal epithelium with evidence of goblet cells, i.e., stage 0 and 1.
Stage 0 - Abundant goblet cell and mucin spots, small epithelial cells; Stage 1 - Fewer goblet cells and mucin spots, small epithelial cells; Stage 2 - Loss of goblet cells and mucin spots, enlarging epithelial cells; Stage 3 - Enlarging or separating epithelial cells; Stage 4 - Large separate epithelial cells with scattered keratinisation, pyknotic nuclei; Stage 5 - Large keratinised epithelial cells with pyknotic nuclei or loss of nuclei.
Statistical analysis was done with Epi Info 6 software (WHO, Geneva, Switzerland). The proportions were compared using the chi-square test and Odds Ratio was used to compare the prevalence of CIC changes in different groups.
Results
The mean age of the control group was 21.8 years and that of the contact lens group was 20.8 years (12-30 years). The specimens from the control group generally revealed numerous plump, oval, deeply pink PAS positive goblet cells amidst a cohesive sheet of small round PAS negative epithelial cells [Figure:1]. Ninety-two (92%) of 100 eyes in the control group were cytologically normal. Eight (8%) eyes were grade 1; and PAS-stained slides showed a reduced number of goblet cells [Figure:2]. Over time, the specimens from contact lens wearing eyes revealed an increase in epithelial cell size and decrease in nuclear/ cytoplasmic (N/C) ratio and loss of goblet cells.
At the end of 3 months there was no significant difference in the appearance of symptoms amongst RGP and soft contact lens wearing eyes [Figure:3]. Severity of cytological alteration was greater in symptomatic than in asymptomatic contact lens-wearing eyes at the end of 6 months. At the end of 6 months, 2 of 30 (6.7%) symptomatic contact lens wearing-eyes were grade 0; 10 (33.3 %) were grade 1; 8 (26.7%) were grade 2 and PAS stained slides showed absence of goblet cells [Figure:4]; 6 (20%) were grade 3 and PAP stained slides showed enlarging and separating epithelial cells [Figure:5]; 2 (6.7%) were grade 4 and PAP stained slides showed enlarged and separated out epithelial cells some, of which were keratinised with orangish cytoplasm [Figure:6]; and 2 (6.7%) were grade 5 and PAP stained slides showed enlarged keratinised epithelial cells with pyknotic nuclei and occasional cells were anucleate [Figure:7]. In the asymptomatic group out of 26 eyes, 12 (46.2%) were grade 0, 10 (38.5%) were grade 1, 2 (7.7%) were grade 2 and 2 (7.7%) were grade 4. No inflammatory component was noticed in any of the slides.
At the end of 6 months, a significantly higher proportion (60.0%) of symptomatic patients showed abnormal CIC changes (grade 2 and above) than asymptomatic patients (15.4%) (Odds Ratio 8.25 (2.00 - 39.75) 95% confidence interval; P = 0.00065) [Table:1].
At the end of 6 months, 60% of symptomatic soft contact lens wearing eyes and 60% of RGP contact lens wearing eyes showed abnormal CIC changes (odds ratio: 1.00 (0.15 - 5.97); 95 % confidence interval; P = 0.649).
At the end of 6 months, none of the asymptomatic RGP contact lens wearing eyes showed abnormal CIC changes whereas 33.4% of the asymptomatic soft contact lens wearing eyes showed abnormal CIC changes (odd ratio: 0.00 (0.00 - 1.14); 95% confidence interval; P = 0.033) [Table:2].
Prevalence of abnormal CIC changes, (grade 2 and above) increases with duration of contact lens wear. A significantly higher proportion (39.3%) of contact lens wearing eyes showed CIC changes after 6 months of continuous contact lens wear compared to those at 3 months (6.3%) P = 0.00001. The odds ratio of developing CIC changes at 6 months compared to that at 3 months was 9.7 (2.8 - 41.2) (95% confidence interval; P = 0.00001) [Table:3].
However no statistically significant difference was observed between the RGP and soft contact lens wearing eyes at 3 months and 6 months [Table:4].
Discussion
The exfoliative and exudative cytologic response of conjunctiva has interested investigators for many years because of the clues it offers to the diagnosis and study of the pathogenesis of many types of conjunctival disorders.[9] Impression cytology has been used to study conjunctival epithelium in several diseases of the ocular surface[4,10] including those induced by contact lenses.[5]
In these studies squamous metaplasia and other morphological alterations of epithelium were demonstrated.[4] Squamous metaplasia is a reversible change in which one adult cell type is replaced by another cell type. The spectrum of morphological changes in squamous metaplasia of conjunctival epithelium includes loss of goblet cells, increase in epithelial cell size, decrease in N/C ratio and keratinisation.
We observed both squamous metaplasia and goblet cell loss in contact lens-wearing eyes. These findings were similar to that of Saini et al,[2] Knop and Brewitt,[5],[6]
Adar et al,[3] and Aragona et al.[4] Snake-like chromatin was not observed in our study. Cytological alteration was seen to occur within 3-6 months of contact lens fitting similar to the observation made by Knop and Brewitt.[6] Prevalence and severity of cytological alteration was significantly greater in symptomatic than asymptomatic contact lens wearers and was seen to increase significantly with increasing duration of lens wear. Our observations are in accordance with the findings of Saini et al.[2] Mechanical irritation by contact lenses may be the cause of squamous metaplasia and goblet cell loss resulting in dry eye, thus leading to symptoms. Whether these symptoms will plateau with time or continue to show changes may be proved only by longterm studies.
Contact lens wear is known to induce tissue inflammation[11] and tear film instability.[12] Contemporary contact lens materials and fitting methodology, when considered in perspective, are remarkably effective. The challenge, however, appears to be the relationship of longterm continuous contact lens wear to the tear film, which in turn affects the ocular surface and the contact lens itself, resulting in alteration in tear fluid composition and reduction in tear production, causing dry eyes. Use of tear film additives (artificial tears) may alleviate the symptoms of contact lens intolerance.
In this prospective study of 6 months there were no significant differences in severity of cytological alteration in RGP and soft lens wearing eyes. However further longterm prospective studies in a larger number of contact lens wearing eyes are recommended in order to assess the effect of various types of contact lenses on the ocular surface.
CIC is a simple and non-surgical technique which allows quantitative assessment of the number of goblet cells in the conjunctiva and provides a better understanding of any pathological behaviour. It not only helps in identifying those at imminent risk of developing symptoms but also helps in assessing the severity of cytological alteration of symptomatic contact lens wearers. In our prospective study, soft contact lens wearers developed abnormal CIC changes [Table:2] at the end of 6 months through they remained asymptomatic. Hence CIC should be recommended in all contact lens wearers whether symptomatic or not, so that patients with CIC changes can be identified at the early stage and followed up regularly. This information could be used for advice for continuation or discontinuation of lens wear.
Acknowledgement
The authors wish to acknowledge the contribution of Dr. R. Chawla, MSc, PhD, for statistical assistance.
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