The Feasibility of Spectral-Domain Optical Coherence Tomography Grading of Anterior Chamber Inflammation in a Rabbit Model of Anterior Uveitis

To determine the feasibility and accuracy of spectral-domain optical coherence tomography (SD-OCT) based grading of anterior chamber cell, using aqueous sampling as a standard, in a rabbit model of anterior uveitis. Adult Dutch-belted rabbits were preimmunized with M. tuberculosis (Tb) H37RA antigen, 1 week prior to induction of anterior uveitis with an intracameral injection of Tb antigen. The anterior chamber was imaged with SD-OCT, followed by a slit lamp examination. Two independent, trained graders recorded their estimate of anterior chamber cell count using the Standardization of Uveitis Nomenclature (SUN) scores for each eye prior to performing an anterior chamber tap to determine the aqueous cell density using a hemocytometer. Using the aqueous cell density as a standard, correlation with SD-OCT counts were compared to those with SUN scores. Overall, SD-OCT correlated well with the hemocytometer counts (Spearman coefficient = 0.53, P < 0.001) compared with SUN grading and hemocytometer counts (Spearman coefficient = 0.02, P = 0.88). The correlation improved to 0.65 (P < 0.001) when we excluded eyes with corneal thickness ≥ 470 μm. Eyes with corneal thickness ≥ 470 μm exhibited the greatest degree of ocular inflammation and corneal opacity. In our rabbit model, SD-OCT grading of anterior chamber cell correlated significantly better with aqueous cell counts, compared to traditional slit lamp grading. Spectral-domain optical coherence tomography grading of anterior chamber cell may be a good alternative to SUN grading. Although SUN grading remains the clinical gold standard, alternative quantitative methods to assess ocular inflammation could provide insight into disease mechanism and aid in measuring treatment response.