Abstract
Abstract: :
Purpose: The rabbit is commonly used preclinically to evaluate the effects of drugs on wound healing following full thickness filtration surgery. Intraocular pressure (IOP) measurements have been used as a major parameter to determine surgical success in this model. However, we have found IOP measurements highly variable in New Zealand white rabbits (NZW). Therefore, as part of an ongoing effort in model development, this study was designed to compare intraocular pressure characteristics pre and post unguarded sclerectomy in Dutch belted (DB) and NZW rabbits, as well as to compare the surgical anatomy between the two strains. Methods: 24 eyes of 12 rabbits were studied. IOPs of 12 normal eyes in 3 DB and 3 NZW rabbits were measured using a TonoPen tonometer in a 27-day period without surgery. IOPs in another 12 eyes were measured in 3 DB and 3 NZW rabbits before unguarded sclerectomy and for up to 10 weeks after surgery using a TonoPen tonometer. Results: 1) Average baseline IOP was higher in DB than in NZW rabbits (27.0 vs. 19.0 mmHg; p< 0.0001). 2) IOP significantly dropped after surgery in both strains. In DB rabbits IOP dropped from a pre-surgery average of 23.9 ± 6.2 to 15.3 ± 6.0 mm Hg (p<0.05) one day after surgery. In NZW rabbits IOP dropped from a pre-surgery average of 18.4 ± 7.7 to 10.3 ± 2.7 mm Hg (p<0.01) one day after surgery. 3) DB rabbits had a higher average post-surgery IOP than NZW rabbits (17.5 vs. 11.6 mmHg; p< 0.0001). 4) Post surgery IOP remained low in DB rabbits within the first 6 weeks post surgery and started to increase thereafter. 5) While performing surgery on DB rabbits, we noted that the anatomic structure of the limbus is more clearly defined in DB than in NZW rabbits, making the surgical procedure easier to perform. We are currently assessing the utility of the TonoPen tonometer vs. pneumotonometer for the IOP measurements, as well as different sclerectomy punch sizes in this model. Conclusion: Our results have shown that the DB rabbit possesses a clearer surgical anatomy, which facilitates surgical procedure. Furthermore, the DB rabbit maintains higher IOPs pre and post surgery, and fails surgery (indicated by increasing IOP) sooner than the NZW, which may provide more defined outcome measures. The DB rabbit may be a better choice to study wound healing modulation following filtration surgery than the NZW rabbit.
Keywords: 316 animal model • 444 intraocular pressure • 315 anatomy