Abstract
Purpose: :
To develop a novel model of ocular inflammation, using the application of Selective Laser Trabeculoplasty (SLT) laser to the iris and then to test the response of inflammation thus created with topical steroids.
Methods: :
Adult male Dutch belted rabbits underwent baseline slit lamp biomicroscopy and baseline flare measurements. In phase one of the study, escalating doses of SLT laser were applied to the iris surface in one eye to determine the optimum power required to generate measurable flare of a few days duration. In phase two one eye of 10 rabbits underwent laser application, with the fellow eye serving as a control. Starting one day prior to SLT, 5 of 10 animals were administered one drop of 20 µl dexamethasone 1%, 4 times daily to the laser treatment eye for five days. The remaining 5 animals were treated with artificial tears to the laser treatment eye as a control. Measurement of IOP and grading of cells and flare were done pre-operatively and daily thereafter, until all values returned to baseline. At the end of the experiments iris sections with or without SLT spots were examined histologically.
Results: :
Application of 200 spots at 2mJ produced repeatable flare of approximately 5 days duration. Compared to controls, dexamethasone significantly suppressed flare on post-SLT day 2 (43.7 ± 21.2 vs.19.1 ± 4.8, p=0.03) and day 3 (33.4 ± 11.0 vs. 16.1 ± 8.7, p=0.03). The difference in clinically observed cells and flare between the steroid and control eyes was not statistically significant. Laser treated eyes showed pitting and pigment clumping in the anterior iris stroma that was not seen in control eyes.
Conclusions: :
SLT laser can be used to generate self-limiting anterior chamber inflammation in rabbit eyes with minimal tissue damage. The steroid responsive nature of the model has potential for use in the evaluation of anti-inflammatory therapies.
Keywords: uveitis-clinical/animal model • inflammation