Cytology of the healthy canine and feline ocular surface: comparison between cytobrush and impression technique
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Updated: Mar 8, 2026
Impression Cytology of the Lid Wiper Area
Published on: August 9, 2016
Anna Perazzi1, Federico Bonsembiante2, Maria Elena Gelain2
1Department of Animal Medicine, Production and Health, University of Padua, Padua, Italy.
Insights
Impression cytology (IC) provided well-preserved ocular surface samples in dogs and cats, though detailed cellular evaluation was challenging. Cytobrush samples showed good cellularity and preservation in both species.
Area of Science:
- Veterinary ophthalmology
- Cytopathology
- Ocular surface disease
Background:
- Impression cytology (IC) is a noninvasive method for sampling the ocular epithelium using filters.
- Evaluating ocular surface health is crucial in veterinary medicine.
Purpose of the Study:
- To compare cytology specimens obtained by impression cytology (IC) and cytobrush from healthy canine and feline eyes.
- Assess the quality of cellular samples for diagnostic purposes.
Main Methods:
- Prospective sampling of healthy canine and feline eyes using polytetrafluorethylene filters (IC) and cytobrush.
- Wright-Giemsa staining and evaluation of cellularity, preservation, and morphology by two observers.
- Analysis of inter-observer agreement and the effect of topical anesthesia.
Main Results:
- IC samples in dogs and cats showed good cellularity and preservation, with superficial and basal-intermediate epithelial cells present.
- Goblet and inflammatory cells were observed in IC samples from both species.
- Cytobrush samples in both species exhibited good preservation and cellularity, with all cell types present but lacking clear separation.
Conclusions:
- Impression cytology (IC) facilitates the collection of ocular surface samples with preserved cytoarchitecture.
- Detailed evaluation of cytoplasmic and nuclear features can be challenging with IC.
- Both IC and cytobrush are viable methods for obtaining ocular cytology specimens in dogs and cats.
Background:
Impression cytology (IC) is a noninvasive technique in which filters are used to sample superficial layers of ocular epithelium.
Objectives:
The aim of this study was to compare cytology specimens obtained by IC and cytobrush from healthy canine and feline eyes.
Methods:
Dogs and cats were prospectively sampled using polytetrafluorethylene filters on the right eye, and cytobrush on the left eye. Wright-Giemsa-stained specimens were evaluated by 2 observers. Cellularity, preservation, and morphology of cells and presence of goblet and inflammatory cells were scored with a 4-grade scale. Inter-observer agreement and effects of topical anesthesia were analyzed.
Results:
In 20 canine IC samples, 10 showed good cellularity (score 2-3) and 13 good preservation. Superficial epithelial cells (SEC) were present in 13/20 of IC, while basal-intermediate cells (BIC) were seen in 14/20. In 6/20 and 7/20, goblet and inflammatory cells were noted, respectively. In 20 cats, 15 of IC showed good cellularity and 14 good preservation, and SEC were present in 16/20 of IC and BIC in 17/20. In 13/20 and 3/20 cats, goblet cells and inflammatory cells were noted, respectively. Canine cytobrush specimens appeared well preserved (9/20) and had good cellularity (8/20). In feline cytobrush specimens, good preservation and cellularity were observed in 16/20 and 14/20, respectively. In both species, all cell types were present without a clear separation. There was moderate to fair agreement about cellular morphology in IC between observers. Specimens obtained with and without anesthesia were comparable.
Conclusion:
Impression cytology allowed collection of samples with maintained cytoarchitecture, while cytoplasmatic and nuclear details were often difficult to evaluate.
