RNA Collection From Human Conjunctival Epithelial Cells Obtained With a New Device for Impression Cytology

To assess the ability of a new device (Eyeprim; Opia Technologies) designed for impression cytology (IC) to harvest RNA from conjunctival cells as compared with the conventional technique.

Cell collection was performed in both eyes using both techniques (conventional and Eyeprim) in different eyes randomized to each technique to avoid bias. The collection order was also randomized. Subjective discomfort assessment was performed using the Symptom Assessment in Dry Eye questionnaire. RNA was quantified in a spectrophotometer. RNA yield and discomfort using each technique were evaluated. A P value ≤0.05 was considered significant.

Twenty healthy subjects (8 men and 12 women) aged 24.7 ± 5.8 years were recruited. The mean corneal fluorescein staining scores were 0.10 ± 0.30 for both eyes (P = 1.0), and the mean phenol red thread tear scores were 28.6 ± 1.9 mm for the Eyeprim and 28.7 ± 2.5 mm for the conventional IC eye group (P = 0.64). No significant (P ≥ 0.45) differences were observed in the mean RNA yield between the Eyeprim and the conventional IC, neither in the total amount (0.32 ± 0.28 μg and 0.26 ± 0.28 μg, respectively) nor in the amount normalized to the membrane area (0.0046 ± 0.0040 μg/mm and 0.0040 ± 0.0043 μg/mm, respectively). No significant differences were observed during (P ≥ 0.17) and after sample collection (P ≥ 0.36) in the frequency or intensity of discomfort (Symptom Assessment in Dry Eye scores).

This pilot study shows that the Eyeprim provides similar RNA yield as the conventional harvesting conjunctival IC technique. It provides enough quantities of material useful for molecular analysis producing comparable levels of discomfort without using anesthesia.