Parafoveal cone abnormalities and recovery on adaptive optics in posterior uveitis

Label-Free Imaging of Inflammation at the Level of Single Cells in the Living Human Eye

Purpose

Putative microglia were recently detected using adaptive optics ophthalmoscopy in healthy eyes. Here we evaluate the use of nonconfocal adaptive optics scanning light ophthalmoscopy (AOSLO) for quantifying the morphology and motility of presumed microglia and other immune cells in eyes with retinal inflammation from uveitis and healthy eyes.

Design

Observational exploratory study.

Participants

Twelve participants were imaged, including 8 healthy participants and 4 posterior uveitis patients recruited from the clinic of 1 of the authors (M.H.E.).

Methods

The Pittsburgh AOSLO imaging system was used with a custom-designed 7-fiber optical fiber bundle for simultaneous confocal and nonconfocal multioffset detection. The inner retina was imaged at several locations at multiple timepoints in healthy participants and uveitis patients to generate time-lapse images.

Main Outcome Measures

Microglia and macrophages were manually segmented from nonconfocal AOSLO images, and their morphological characteristics quantified (including soma size, diameter, and circularity). Cell soma motion was quantified across time for periods of up to 30 minutes and their speeds were calculated by measuring their displacement over time.

Results

A spectrum of cell morphologies was detected in healthy eyes from circular amoeboid cells to elongated cells with visible processes, resembling activated and ramified microglia, respectively. Average soma diameter was 16.1 ± 0.9 μm. Cell movement was slow in healthy eyes (0.02 μm/sec on average), but macrophage-like cells moved rapidly in some uveitis patients (up to 3 μm/sec). In an eye with infectious uveitis, many macrophage-like cells were detected; during treatment their quantity and motility decreased as vision improved.

Conclusions

In vivo adaptive optics ophthalmoscopy offers promise as a potentially powerful tool for detecting and monitoring inflammation and response to treatment at a cellular level in the living eye.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

MULTIMODAL IMAGING OF POSTERIOR POLAR ANNULAR CHOROIDAL DYSTROPHY

BACKGROUND

Posterior polar annular choroidal dystrophy (PPACD) is a rare disease. Patients with PPACD show loss of retinal pigment epithelium and choriocapillaries surrounding the vascular arcades and optic nerve.

METHODS

Two patients with PPACD were evaluated with multimodal imaging, including fundus autofluorescence (FAF) and adaptive optics (AO).

REPORT OF CASES

One patient (32 year old, one eye) with PPACD was followed up for 3 years. Best-corrected visual acuity (BCVA) was stable at 20/40, whereas a slight enlargement of paravascular atrophy of pigment epithelium was observed at fundus autofluorescence (FAF). Adaptive optics obtained at last examination showed reduced density of foveal cone photoreceptors. The second patient (30 year old, two eyes) with PPACD showed bilateral normal BCVA, associated with reduction in the density of foveal cone photoreceptors.

CONCLUSION

At FAF, longitudinal follow-up of PPACD showed progression of the paravascular atrophy of the pigment epithelium. Foveal cone photoreceptors can be reduced even in the presence of preserved visual acuity.