Abstract
Purpose: :
Fluorophotometry is a well validated method for assessing corneal permeability in human subjects. However, its use in animals has not been well evaluated. The purpose of this study was to evaluate corneal epithelial permeability after desiccating stress using a murine-modified Fluorometer.
Methods: :
Corneal permeability was evaluated prior to and after subjecting 6-8 week old C57BL/6 mice to experimental dry eye (EDE) for 2 and 5 days (n=10/time point). Untreated mice served as controls. Fifteen microliters of 0.001% sodium fluorescein (NaF) were instilled topically into each mouse’s left eye to create an eye bath, and left to permeate for 3 minutes. The eye bath was followed by a generous wash with Buffered Saline Solution (BSS) and alignment with the Fluorometer. Seven corneal scans using the Fluorotron Master were performed during 15 minutes (1st post-wash scans), followed by a second wash using BSS and another set of five corneal scans ( 2nd post-wash scans) during the next 15 minutes. Corneal permeability was calculated using Fluorometer software.
Results: :
There was no statistical difference in the corneal fluorescein permeability of the 1st post- wash scans after 2 days or 5 days of EDE compared to untreated mice (1115.64±118.94, 1160.21±108.26 vs. 1000.47±75.56 ng/mL, P>0.05 for both, respectively). However, the 2nd post-wash scans demonstrated that EDE caused a significant NaF retention at both 2 and 5 days of EDE compared to baseline, untreated controls (1017.92±116.25, 1015.40±120.68 vs. 528.22±127.85 ng/mL, P<0.05 for both, respectively).
Conclusions: :
Desiccating stress increases permeability of the corneal epithelium to NaF, and increases NaF retention in the corneal stroma. A Fluorometer modified to accomodate mice can be a useful and sensitive tool to evaluate corneal permeability in murine dry eye.
Keywords: cornea: tears/tear film/dry eye