Abstract
Purpose :
We have previously published data in a rat model of suture induced corneal neovascularisation. However, the small size of the rat eye creates challenges in evaluation of the results and limits the dose volume that can be administered, precluding the dosing of clinically relevant or active doses. The rabbit eye is large enough to avoid these issues, thus facilitating the evaluation of the results. The purpose of this study was to provide background data on neovascular growth parameters in the New Zealand White rabbit following placement of a single silk suture within the cornea and to confirm suitability for use as a screening model.
Methods :
Under anesthesia, a single 9.0 silk suture was placed in one cornea/animal approx. 1-2 mm from the limbus, extending toward the center. One group of 6 rabbits received a subconjunctival injection of 0.9% saline and a second group of 6 rabbits received a subconjunctival injection of bevacizumab (5 mg) on Days 1 and 7. Dose volume was 200 μL. Analgesia was provided as necessary. Blue reflectance images were obtained using a cSLO on Days 7 and 14. The length of the vessel incursion was measured from the limbus to the distal end of the encroaching CNV using a digital micrometer (in millimeters). Qualitative assessments included the percentage estimate of involved corneal circumference and the extent of vessel branching.
Results :
Mean vessel length for the saline-treated eyes was 1.1±0.5 mm on Day 7 and 2.7±0.75 mm on Day 14, compared to 0 mm and 0.4±0.8 for the bevacizumab eyes on Days 7 and 14, respectively. Circumferential vascularised area was 30±8% and 20±5% on Days 7 and 14, respectively for the saline eyes. Area in bevacizumab treated eyes was 0% on Day 7 and 13±5% on Day 14. The amount of vessel branching increased from slight to moderate in saline eyes over 14 days, while only very slight branching was observed in bevacizumab eyes on Day 14.
Conclusions :
A single silk suture placed in the rabbit cornea resulted in generation of neovessels in the cornea that continued to grow over a 2 week period in saline treated eyes. In our laboratory, the model was sensitive to the anti-VEGF antibody bevacizumab, which was consistent with previously published data in other laboratories using this rabbit model and demonstrated the model may be of use for screening anti-VEGF compounds.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.