Non-invasive evaluation of microscopic retinal pathology in macular telangiectasia type 2

Abstract

 

Purpose

 

To characterize photoreceptor, retinal pigment epithelium (RPE) and vascular changes in macular telangiectasia (MacTel) type 2.

 

Methods

 

Seven subjects, average age 63 years, diagnosed with MacTel type 2 at various stages were imaged in one eye using confocal adaptive optics scanning light ophthalmoscopy (AOSLO) and spectral domain optical coherence tomography (SD-OCT). In addition, split-detection AOSLO was used in four subjects to visualize the photoreceptor inner segments, vasculature, and inner retina, while dark-field AOSLO was used to image the RPE mosaic. Vascular perfusion maps were generated as the standard deviation of split-detection AOSLO image sequences. The area of ellipsoid zone (EZ) lesion was measured with en face SD-OCT.

 

Results

 

SD-OCT revealed disruptions of the EZ in 6 of 7 eyes (average 0.074mm²), with corresponding dark-regions of reduced or complete loss of photoreceptor reflectivity in confocal AOSLO imaging. RPE cells were seen with dark-field AOSLO in the center of two of the EZ lesions, where the photoreceptors appear to have degenerated. Split-detection revealed swollen cone inner segments on the edges of these lesions in 3 of 4 imaged patients, as well as microcysts ranging in size from 2 to 100 µm in all subjects, which were not always visible in SD-OCT. Fibrotic-like structures on the inner retinal surface as well as sharply demarcated cavitations were present in all subjects. Vascular perfusion maps revealed abnormally enlarged and tortuous vessels in all subjects and microaneurysms in two out of four subjects over the central 3° around fixation.

 

Conclusions

 

The combination of multiple AOSLO imaging techniques with SD-OCT is useful for non-invasive study of the micro-pathology in MacTel. Specifically, dark-field AOSLO disambiguates the reflectivity inside and surrounding EZ lesions identifying reflective structures as RPE cell granules, while split-detection AOSLO reveals photoreceptor swelling and microaneurysms, which could be useful as biomarkers of disease activity and progression.

 

 

Multimodal in vivo imaging on the border of a MacTel lesion: A) Confocal AOSLO; B) Split-detector AOSLO; C) Dark-field AOSLO; and D) en face SD-OCT of the EZ defect (*). This imaging shows cone photoreceptor swelling at the edge of the EZ defect (B) and illustrates how bright spots in confocal AOSLO images could be misinterpreted as cones (A versus C). Scale bar 50 µm.

 

Keywords: 688 retina • 494 degenerations/dystrophies • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)