Retinal Imaging using the Heidelberg Spectralis High Magnification Module: A Pilot Study

Abstract

Purpose : To evaluate the utility of a high magnification module (HMM) to visualize retinal photoreceptors, nerve fiber layer (NFL) and superficial retinal vasculature in physiologic and pathologic retinal conditions.

Methods : This is an observational descriptive study. Normal and pathologic maculae were imaged in vivo using still and video HMM lens modes, with fixation and contrast adjustments to enhance visualization. HMM images were qualitatively classified based on structures identified as either good - when photoreceptors (PR) could be visualized, average - when PR were not visualized while retinal vessels and structural changes could be seen, or poor - when there were no identifiable structures. Selected eyes with retinal pathologies were also imaged with fundus photography, optical coherence tomography (OCT), OCT angiography (OCTA), indocyanine green (ICG) and fluorescein angiography (FA).

Results : From 32 eyes imaged (16 normal and 16 pathologic retinas), 12 of the normal and 11 of the pathologic retinas demonstrated at least average image quality (12 normal and 2 pathologic eyes presented good quality images, respectively). A mosaic pattern of hexagonal shapes with variable reflectivity (representing PR) was seen in 12 normal eyes, mainly in the parafovea, but could not be resolved in the majority of pathologic retinas. Mosaic patterns appeared sharpest in the parafoveal region. Difficulty in resolving the photoreceptors in the umbo, fovea, and peri-fovea was encountered. The NFL was seen as arcuate hyperreflective bundles. Flow was observed in the macular microvasculature. Poorly resolved PR and scattered hyperreflective foci were correlated with changes in RPE in the pathologic retinas (Age related macular degeneration, central serous chorioretinopathy). Macular striae were seen in eyes with ERM. Imaging artifacts that were attributed to the optics of the lens and light polarization were visualized in the majority of the images.

Conclusions : In the majority of eyes, irrespective of whether retinal pathology was present, it was challenging to obtain average or above-average image quality. In cases with good quality imaging, the parafoveal photoreceptor mosaic, vascular flow and various features of pathologic eyes could be visualized.

This is a 2020 Imaging in the Eye Conference abstract.

 

Lucent circle(arrow)is an artifact, attributed to the optics of the lens and light polarization.Ai-iii.Good quality image. Bi-iii.Average image. C. i-iii.Poor quality image.