Objective Quantification of Posterior Segment Inflammation: Measuring Vitreous Cells and Haze Using Optical Coherence Tomography

PURPOSE: To objectively grade posterior segment in-flammation by measuring vitreous cells and haze on opti-cal coherence tomography (OCT) scans and to compare OCT-based results with clinical grading. center dot DESIGN: Evaluation of a diagnostic test.METHODS: OCT scans of patients with uveitis were collected at 3 timepoints: with active (T0), clinically im-proving (T1), and resolved (T2) inflammation. At each visit, visual acuity and clinical grading of the vitreous haze (National Eye Institute [NEI] scale) were assessed. The density of vitreous cells was calculated on each OCT scan manually and automatically through a bespoke algo-rithm. Vitreous haze was indirectly measured on OCT scans by calculating the vitreous/retinal pigmented ep-ithelium (VIT/RPE)-relative intensity manually and au-tomatically. The variation of OCT-derived measurements over time was assessed. OCT-derived measurements were compared with clinical grading.RESULTS: A total of 222 scans from 74 eyes were an-alyzed. Both vitreous cell density and VIT/RPE-relative intensity significantly decreased over time. Cell density correlated with the clinical grading with a significant increase at each grade of the NEI scale. By contrast, the VIT/RPE-relative intensity was positively correlated with the clinical grade overall but there was no significant difference when comparing contiguous grades of the NEI scale. Infectious uveitis had a higher cell density. The in-traclass correlation coefficient between manual and auto-matic assessment was 0.83 for cell density and 0.423 for the VIT/RPE-relative intensity. CONCLUSIONS: Posterior segment inflammation could be objectively graded through OCT scans. Vitreous cell density was assessed manually and automatically with good agreement and correlated better with NEI clini-cal grading compared with VIT/RPE-relative intensity.

Automated summary

Posterior segment inflammation can be objectively graded through OCT scans. The density of vitreous cells and the VIT/RPE-relative intensity decrease significantly over time. Cell density is correlated with clinical grading, showing a significant increase at each grade of the NEI scale. On the other hand, VIT/RPE-relative intensity is positively correlated with the overall clinical grade, but there is no significant difference when comparing contiguous grades of the NEI scale. Infectious uveitis has a higher cell density. The interclass correlation coefficient between manual and automatic assessment is 0.83 for cell density and 0.423 for the VIT/RPE-relative intensity.