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

PURPOSE

To objectively grade posterior segment inflammation by measuring vitreous cells and haze on optical coherence tomography (OCT) scans and to compare OCT-based results with clinical grading.

DESIGN

Evaluation of a diagnostic test.

METHODS

OCT scans of patients with uveitis were collected at 3 timepoints: with active (T0), clinically improving (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 algorithm. Vitreous haze was indirectly measured on OCT scans by calculating the vitreous/retinal pigmented epithelium (VIT/RPE)-relative intensity manually and automatically. 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 analyzed. 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 intraclass correlation coefficient between manual and automatic 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 clinical grading compared with VIT/RPE-relative intensity.