Microangiopathic Features of Central Retinal Vein Occlusion Imaged Using Fluorescence Adaptive Optics Scanning Light Ophthalmoscopy

Abstract

 

Purpose

 

Central retinal vein occlusion (CRVO) remains a common cause of vision loss in retinal vascular disease, second only to diabetic retinopathy. Fluorescein angiography (FA) has remained the gold standard for confirming its diagnosis and assessing the degree of retinal nonperfusion, macroangiopathic change and macroscopic response to treatment. The high transverse resolution of adaptive optics scanning light ophthalmoscopy (AOSLO) has allowed for in vivo study of retinal micropathology, but has been limited in its capability to image retinal microvasculature. Here, we demonstrate the use of fluorescence AOSLO (FAOSLO) for imaging microscopic angiopathic features of CRVO.

 

Methods

 

Reflectance AOSLO (RAOSLO) images (790nm; 1° field of view) were collected in five adult CRVO patients to identify microvascular points of interest. Patients then ingested 1g fluorescein dye. Simultaneous RAOSLO and FAOSLO images were then collected between 15 and 60 minutes post-ingestion. The fluorescence channel used a 488nm light for excitation; and, an emission filter centered at 525nm with a 45nm bandwidth. For comparison with conventional imaging techniques, Topcon fundus imaging with and without IV fluorescein was performed.

 

Results

 

The combination of RAOSLO and FAOSLO enabled us to visualize CRVO microangiopathic features in vivo in the finest capillaries of the retinal inner nuclear layer. Among the features visualized were vessel wall thickening, microaneurysms, neovascularization and hemorrhage. FAOSLO showed the full extent and detail of microangiopathy, as opposed to RAOSLO and conventional fundus photography.

 

Conclusions

 

We believe that the clinical role of FAOSLO has significant potential. Comparison with motion contrast-based techniques remains to be evaluated. We believe that coupled with RAOSLO and a method to analyze microangiopathic features quantitatively, FAOSLO will lead to a better understanding of CRVO pathophysiology, disease progression and a more comprehensive method in monitoring tissue response to different treatment modalities.

 

 

Fig 1. Fine capillary microaneurysms were seen (C, D) that were not appreciated on either conventional imaging (A, B) or RAOSLO.

 

 

Fig 2. RAOSLO was better at visualizing hemorrhage (B) and vessel wall thickening (D), whereas FAOSLO was better at outlining the intravascular space and visualizing capillaries of finest caliber (C, E).

 

Keywords: 688 retina • 749 vascular occlusion/vascular occlusive disease • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)