Abstract
Purpose :
The cornea alkali burn model is an established method of replicating ocular surface damage in animal subjects. Here, we report the dynamic changes captured by in vivo confocal microscope (IVCM) imaging in an alkali-burned rat cornea model and investigate the application of qualitative IVCM assessment to monitor pathological changes in the cornea.
Methods :
Alkali burns were induced in Sprague-Dawley rat corneas by applying 0.5N NaOH for 90 seconds. IVCM images were acquired at D2, D5, D10, and D21 after injury. Three regions were randomly selected on each rat cornea and continuous volume acquisitions were taken from corneal surface to endothelium at each region. Images of superficial epithelium, basal layer, anterior and posterior stroma, and endothelium were analyzed at various time points. Corneal basal cell size, corneal thickness, and epithelial thickness were assessed longitudinally as well.
Results :
Ocular surface integration was disrupted two days after injury by the spotted loss of superficial epithelium, with epithelial repair becoming evident at D5-D10. At 21 days, there was no apparent difference between superficial epithelia in injured and control corneas. The basal layer of the epithelium showed damage at D2, but integration was restored by D5. The anterior stroma was hyperreflective at D2 and became persistently hyperreflective at D10-D21 with indiscernible cellular structure. Additionally, the posterior stroma showed loss of structural detail at D2 but recovered gradually at D10-D21. Significant inflammatory cell infiltration was noted in the endothelium and anterior chamber at D2-D5. Quantitatively, average basal layer cell counts were 2709±254/mm2 at D5 compared to 3954±297/mm2 (control) with gradual return to 3831±410/mm2 at D21 (D5 vs CTRL: p<0.0001, D5 vs D21: p<0.0001, Student’s t-test). Corneal thickness (measured from superficial epithelium to endothelium) increased from 225±27 µm to 274±11 µm at D2, 271±13 µm at D5, 208±11 µm at D10, and 240±8 µm at D21 (p<0.001, ANOVA). Epithelium thickness remained at 29µm throughout the measured duration.
Conclusions :
In a rat cornea alkali burn model, IVCM imaging indicated that recovery of epithelium, endothelium, and posterior stroma could be expected by D21, with damage to the anterior stroma being shown to persist past D21. These findings demonstrate the potential for qualitative IVCM image analysis as a useful tool for monitoring cornea repair.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.