Quantitative analysis of vitreous inflammation using optical coherence tomography in patients receiving sub-Tenon's triamcinolone acetonide for uveitic cystoid macular oedema

Background/aims To evaluate the vitreous signals obtained on spectral domain optical coherence tomography (SD-OCT) in patients with uveitic cystoid macular oedema (CMO) and compare these signals before and after sub-Tenon's triamcinolone acetonide injection. Methods Retrospective study with standardised longitudinal imaging preintervention and postintervention. The study cohort comprises 22 patients (22 eyes) with uveitic CMO receiving a sub-Tenon's triamcinolone acetonide (STTA) injection. Post hoc analysis of SD-OCT images using custom software provided an 'absolute' measurement of vitreous signal intensity, which was expressed as a ratio to the retinal pigment epithelium intensity ('VIT/RPE-relative intensity') in arbitrary units. Main outcome measure Difference in VIT/RPE-relative intensity before and after treatment. Results Treatment with STTA resulted in a significant reduction in VIT/RPE-relative intensity, which was associated with both a reduction in central retinal thickness (CRT) and improvement in visual acuity. Mean (SD) VIT/RPE-relative intensity pretreatment was 0.139 (0.074) versus 0.053 (0.028) post-treatment (p=3x10(-5)). Mean (SD) CRT was 581 mu m (119 mu m) pretreatment versus 333 mu m (95 mu m) post-treatment (p=2x10(-8)); the mean reduction in CRT was 248 (95% Cl 189 to 306). The correlation coefficient between VIT/RPE-relative intensity and CRT was 0.534 (p=0.011) and between VIT/RPE-relative intensity and visual acuity was 0.702 (p=0.0001). Conclusions This study provides evidence that the OCT-derived VIT/RPE-relative intensity may be useful as a quantitative and objective marker of disease activity and treatment response in uveitis complicated by CMO. This first longitudinal study of this novel OCT parameter is an encouraging step in the development of sensitive objective OCT-based endpoints for trials of efficacy in uveitis.