Related Experiment Video
Updated: Apr 30, 2026
Impression Cytology of the Lid Wiper Area
Published on: August 9, 2016
[Evaluation of conjunctival epithelium of filtering blebs by impression cytology]
M J Muniesa1, S González2, P Buetas2
1Departamento de Oftalmología, Hospital Universitari Arnau de Vilanova, Lérida, España; Institut de Recerca Biomèdica de Lleida (IRB Lleida), Lérida, España.
Purpose:
To study the ocular surface in filtering blebs using impression cytology, comparing the bleb side and areas outside the bleb edges.
Methods:
Twelve filtering blebs of 8 patients were included: 4 cases of trabeculectomy without mitomycin C (MMC), 6 cases of trabeculectomy with MMC, and 2 cases of non-penetrating glaucoma surgery. Impression cytology specimens were taken from filtering blebs as well as outside the bleb area. A classification scale from 0 to 3 was used to describe the distribution of epithelial cells and the density of goblet cells. Grade 0 indicated cohesive epithelial cells and abundant goblet cells; and the grade 3 indicated loss of epithelial cohesion and absence of goblet cells.
Results:
The mean grade of cytology in filtering blebs was 2.4 ± 0.9, and in the outside bleb area of 0.8 ± 0.3 (P<.001). These differences were independent of the use of MMC (P=.48). The large majority (83%) of filtering blebs showed a decrease in epithelial cohesion and absence of goblet cells. Outside the bleb area, 100% of the cases had cohesive epithelial cells with different grades of goblet cells.
Conclusion:
The conjunctival epithelium overlying the filtering blebs showed significant changes that consisted of increased intercellular spaces and loss of goblet cells. These increased intercellular spaces could explain the trans-epithelial pathway of aqueous humor. The least amount of mucin due to loss of goblet cells could contribute to increase the risk of infection in filtering blebs.
