Changes in Outer Retinal Structure Following Closed Globe Blunt Ocular Trauma

Abstract

 

Purpose

 

Imaging with adaptive optics scanning light ophthalmoscopy (AOSLO) has shown persistent photoreceptor mosaic disruption following ocular trauma, though only a single time point was examined. Here, we assess changes in photoreceptor structure over time following closed globe blunt ocular trauma and employ a novel AOSLO imaging modality to better delineate the extent of photoreceptor disruption in these patients.

 

Methods

 

Two subjects with histories of visual complaints following ocular trauma were initially imaged between 4 and 6 months post trauma. To assess changes in outer retinal structure, imaging was repeated 4 to 15 months later. SD-OCT was used to acquire high-density volume scans through the fovea for assessment of retinal architecture. Confocal and split-detector AOSLO were used to visualize the waveguided and non-waveguided photoreceptor signals, respectively.

 

Results

 

In one subject the area of the ellipsoid zone (EZ) disruption decreased between 6 and 21 months post trauma from 0.070 to 0.017mm² on SD-OCT and from 0.075 to 0.029mm² on confocal AOSLO. Confocal AOSLO imaging on a second subject revealed diffuse photoreceptor disruption that remained grossly unchanged between 4 and 8 months post trauma. In both subjects, visualization of the inner segments by split-detector AOSLO allowed for more definitive assessment of residual cone structure. In one subject, confocal AOSLO overestimated the focal lesion size by over 300% with respect to split-detector AOSLO (Figure). Split-detector imaging also revealed the presence of enlarged cones bordering the focal photoreceptor mosaic disruption (Figure), and microcysts in areas of parafoveal photoreceptor mosaic disruption visualized by confocal AOSLO.

 

Conclusions

 

Assessment of the degree of residual cone structure following trauma is challenging when relying solely on confocal AOSLO imaging and/or en face SD-OCT. Split-detector imaging was able to disambiguate reflective signals derived from remaining cones from those originating from other retinal structures, and this technique may be useful as a prognostic indicator of expected recovery in these patients.

 

 

Logarithmic grayscale confocal AOSLO (left) overestimates the area of focal photoreceptor disruption by 322%, as compared to split-detector AOSLO (right). Scale bar= 100µm.

 

Keywords: 550 imaging/image analysis: clinical • 648 photoreceptors • 742 trauma