Abstract
Purpose :
While dacryoadenectomy is a commonly employed method to establish animal dry eye disease model, there is limited research in systematically monitoring its development longitudinally. In vivo confocal microscopy (IVCM) is a powerful tool to examine the cornea in vivo. Here we applied the Heidelberg Retina Tomograph III with Rostock Cornea Module (HRT III-RCM) to a murine double dacryoadenectomy model to examine the effect of dry eye disease on the cornea.
Methods :
Five (5) Sprague-Dawley rats (aged 8-9 weeks, male) underwent double dacryoadenectomy to remove the intraorbital and extraorbital lacrimal glands. Male rats were chosen in this study due to a lesser influence of hormone cycle. A modified Schirmer’s tear test, blink tests and IVCM images were acquired pre-surgery and at 1, 2 and 4 weeks post-surgery. Location and depth of up to three nerves per eye were randomly selected in the sub-basal nerve plexus (SNP). Same areas were identified by locating them in SNP layer and re-imaged as volume acquisition in subsequent weeks. Data were presented as Mean+SEM, and p values were calculated by Student’s t test.
Results :
After double dacryoadenectomy, aqueous tear production measured by Schirmer’s test were reduced by 45% (1.03 ± .04 vs. 1.88 ± .19 mm/5 min, *p=0.024) and blink rate increased to 237% (24.9 ± 3.5 vs. 10.5 ± 2.2 blinks/5 min, **p<0.001) compared to pre-surgery value. We observed distinct differences between pre- and post-surgery corneal morphologies using IVCM. Starting from 1 week after surgery, massive inflammatory cell infiltration was observed throughout the SNP which peaked at week 1 and subsided at week 2. Nerve branches swelled and showed noticeable nerve sprouting. These trends were also seen in nerve trunks located in the stroma. Furthermore, in the stroma, we noticed that activated keratocytes were present through week 4. Blood vessels and fibrous elements were also more prominent in post-surgery than pre-surgery corneas.
Conclusions :
Here we demonstrated that the HRT III-RCM could be employed to non-invasively monitor pathophysiological changes of dry eye disease. It revealed that differential changes in corneal nerves as well as corneal epithelia and stroma.
This is a 2021 ARVO Annual Meeting abstract.