Abstract
Purpose: :
To observe changes in corneal thickness with Optical Coherence Tomography (OCT) in the rat model of Keratoconjunctivis Sicca (KCS) and Neurotrophic Keratitis (NK) involving Trigeminal Nerve Denervation.
Methods: :
The conditions of NK and KCS were induced in the left eye of the rat by ablating the V1-V2 junction of the left trigeminal nerve using radio frequency ablation. The left eye was the experimental, while the right eye served as a control. OCT imaging of the corneas was performed at 1.5 and 2.5 weeks post trigeminal nerve ablation, where images of apex of the cornea were obtained. The images were analyzed using ImageJ software where a Median filter was first applied to reduce light noise in the images. The thickness of the cornea was determined by obtaining a pixel intensity profile from the anterior to the posterior of the apex of the cornea. A quantitative value of the corneal thickness was determined by calculating the pixel distance between the first and last high intensity distribution on the intensity profile.
Results: :
At 1.5 weeks after trigeminal nerve ablation, the average corneal thickness was measured to be 267 pixels (left eye) and 78.8 pixels (right eye). The pixel distance calculated from the OCT images at 2.5 weeks after trigeminal nerve ablation showed a slight increase in the right eye by 6.80% and a decrease in the left eye by 20.04%. However the average corneal thickness in the left eye was still significantly greater than the right eye. A T-test of Statistical Significance was performed comparing both eyes at 1.5 and 2.5 weeks, with a p-value of 0.0013 and 0.0022, respectively.
Conclusions: :
The condition of NK is characterized by an increase in corneal thickness and melting of the corneal stroma. The results obtained from the OCT Imaging indicated the presence of NK by the increase in corneal thickness on the experimental eye as compared to the control eye 1.5 and 2.5 weeks after trigeminal nerve ablation. The results from OCT imaging correlated with previous research in increase of inflammatory proteins, decrease in tear production and corneal sensitivity in the left eye, indicating the condition of KCS together with NK. The use of OCT imaging to monitor corneal thickness has shown that a long term animal model of NK and KCS can be obtained by the trigeminal nerve ablation.
Keywords: cornea: stroma and keratocytes • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)