Novel Imaging Biomarker Discovered for Posterior Uveitis

Maximilian W. M. Wintergerst

A recent study introduced a novel biomarker for posterior uveitis which postulates previously undetected sources of green and red emission fluorescent components (GEFC/REFC). The condition, classified as an rare disease, is a heterogeneous group of diseases that are not fully understood.

According to investigators, clinical discrimination and management of these conditions constitute an ongoing challenge. The team sought to determine novel diagnostic methods in order to increase comprehension and differentiate between disease categories.

Maximilian W. M. Wintergerst, Department of Ophthalmology, University Hospital Bonn, Venusberg-Campus 1, and investigators conducted a retrospective study evaluating patients from various outpatient clinics who were diagnosed with posterior uveitis.

The Evaluation

The study included patients (from October 2017-March 2021) with one of the following diagnoses: acute posterior multifocal placoid pigment epitheliopathy (APMPPE); ocular sarcoidosis mimicking birdshot chorioretinopathy in terms of non-pigmented bright lesions; punctate inner choroidopathy (PIC); birdshot chorioretinopathy; toxoplasmosis chorioretinitis; multifocal choroiditis and panuveitis (MCP); presumed ocular histoplasmosis syndrome (POHS); or serpiginous choroiditis.

Pupil dilation was performed on participating patients with 0.5% tropicamide and 2.5% phenylephrine before they underwent examination by an ophthalmologist and were then imaged by color-fundus photography (CFP, 440–650 nm), fundus autofluorescence (FAF) with blue excitation light and infrared reflectance as well as enhanced depth spectral-domain optical coherence tomography.

Exclusion criteria consisted of idiopathic forms of posterior uveitis, reduced image quality, significant vitreous opacities, advanced cataract, inability to perform the examination, or presence of other retinal disease aside from the stigmata of posterior uveitis.

Novel Imaging Biomarkers for Posterior Uveitis

Results revealed a total 76 eyes of 45 patients were included and the presence of 845 lesions observed. Extrapolated data from the evaluation demonstrated involvement of both short and long-wavelength emitting fluorophores in retinal and choroidal lesions, as well as significantly different green and red emission fluorescent component ratios in lesions across various posterior uveitis entities.

“The GEFC/REFC ratio of retinal and choroidal lesions was significantly different between distinct subgroups," investigators wrote. "Hence, this novel imaging biomarker could aid diagnosis and differentiation of posterior uveitis entities.”

No relevant lens opacities were identified among the included phakic eyes. Clinically active inflammation at image presentation was observed in 3 out of 13 eyes with ocular sarcoidosis (22 lesions), 2 out of 9 eyes with birdshot chorioretinopathy (23 lesions), 2 out of 22 eyes with APMPPE (29 lesions), 1 out of 12 eyes with PIC (11 lesions), 2 out of 8 eyes with toxoplasmosis (2 lesions), and 4 out of 5 eyes with serpiginous choroiditis (10 lesions).

Included eyes with multifocal choroiditis and panuveitis and presumed ocular histoplasmosis syndrome didn’t contain any active lesions.

“Our study introduced GEFC/REFC ratios as a novel imaging biomarker for posterior uveitis using spectrally resolved fundus autofluorescence and provides means for differentiation of posterior uveitis entities, which can be difficult to distinguish otherwise," investigators wrote.

"Furthermore, we found previously unknown sources of REFC and GEFC. Longitudinal studies are warranted to evaluate the use of spectrally resolved FAF for diagnosis and monitoring of posterior uveitis," they concluded.

The study, "Spectrally resolved autofluorescence imaging in posterior uveitis" was published in Scientific Reports.