Moxifloxacin-based fluorescence microscopy for evaluating in vivo conjunctival goblet cells in a dry eye rabbit model and its safety in human conjunctival epithelial cells

Abstract

Purpose : To evaluate conjunctival goblet cells (GCs) in a dry eye rabbit model by using moxifloxacin-based fluorescence microscopy (MBFM) and the safety of MBFM by using cultured human conjunctival epithelial cells (HCECs).

Methods : Nine New Zealand white rabbits were used. MBFM imaging was performed both immediately and 15 min after topical instillation of moxifloxacin 0.5% ophthalmic solution (Vigamox^®; Alcon) to evaluate how long moxifloxacin staining was maintained in two rabbits. Seven rabbits were used for the desiccating stress–induced dry eye model. In the first 2 weeks, the right eye was blinked once per min for 30 min every two days. In the next 2 weeks, the same procedure was repeated with an airflow of 2.5 m/s. Corneal fluorescein staining, tear film break-up time (TBUT) were evaluated every 2 weeks together with MBFM imaging of the superior bulbar conjunctiva at 5 mm from the limbus. For the safety study, HCECs were exposed to the maximum energy light (405 nm, 0.1415 W/cm²) used in MBFM for various time durations of 1, 3, 5, and 10 s with moxifloxacin instilled, and MTT and BrdU assays were performed after 2 and 24 h.

Results : In vivo GC imaging was possible with light exposures of less than 2 s and up to 15 min after a single moxifloxacin instillation without significant signal reduction. The density of GCs (GCs/mm²) from MBFM in the right eyes of the dry eye rabbit model was 1515±314 in the baseline, 1450±355 in 2 weeks, and 928±331 in 4 weeks, and the density in the control left eyes was unchanged. The corneal staining score and TBUT were significantly worsened in 2 weeks (7.7±1.0 s, 5.8±0.8 s, respectively) and 4 weeks (7.6±1.5 s, 6.6±0.5 s, respectively), compared to the baseline (3.0±1.3 s, 11.5.8±2.1 s, respectively). Apoptotic and proliferative capacity of HCECs were unaffected by the maximum excitation energy up to 10 s.

Conclusions : MBFM GC imaging was possible within 15 min after a single instillation of moxifloxacin. MBFM imaging showed the decrease of GC density in dry eye rabbit models in consistent with other clinical evaluations. MBFM imaging was safe and MBFM would be a valuable GC imaging device in the clinical setting.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.