Purpose:
To correlate visual function with high-resolution structural imaging in patients with Acute Macular Neuroretinitis (AMN).
Methods:
Best-corrected visual acuity (VA), Goldmann kinetic and automated perimetry and fundus-guided microperimetry, full-field and multifocal electroretinography (ffERG and mfERG), spectral domain optical coherence tomography (SDOCT) and Adaptive Optics Scanning Laser Ophthalmoscopy (AOSLO) imaging were used to correlate retinal structure and function in 2 patients with bilateral AMN. Structural properties of the cones were imaged in both subjects using AOSLO and compared with 27 normal eyes.
Results:
Two female patients, A and B, aged 22 and 40, respectively, presented with acute focal loss of central visual acuity, photopsia, minimal funduscopic changes, and electroretinographic abnormalities 1 and 4 years prior to imaging. Both individuals reported sudden onset of symptoms in one eye after a prodromal systemic illness with some initial progression of scotomata and photopsias. After an interval of several weeks or months, the second eye became involved but with less severity. MfERG response densities were decreased with delayed timing in the affected areas, although ffERG amplitudes showed no significant interocular asymmetry. SDOCT showed loss of the outer nuclear layer and discrete disruption in the inner segment-outer segment junction at the fovea in both patients. Patient A showed structural changes in the optical components of the photoreceptors, with discrete regions in which the cones were not visualized and SDOCT showed discrete loss of the inner and outer retinal layers corresponding to visual field defects and mfERG abnormalities. In patient B, the severe loss of VA, dense central scotoma and reduced mfERG responses were observed extending beyond the central abnormalities in cone structure as defined by the AOSLO and represented significant dysfunction in regions with relatively preserved cone structure.
Conclusions:
AOSLO imaging, SDOCT and fundus-guided microperimetry demonstrated anatomical heterogeneity among patients with the clinical diagnosis of AMN. In both patients abnormalities in retinal structure corresponded to reduced visual function, but in patient B, the functional abnormalities extended into regions where photoreceptor structure was relatively preserved. These differences may reflect different forms of or etiologies for AMN and may be relevant to future prospects for visual recovery or ongoing vision loss.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • retina: distal (photoreceptors, horizontal cells, bipolar cells)