Normal retinal vasculature imaged using fluorescence adaptive optics scanning light ophthalmoscopy (FAOSLO)

Abstract

 

Purpose

 

To report high resolution images of retinal vasculature using Fluorescein Angiography (FA) with the Adaptive Optics Scanning Light Ophthalmoscope (AOSLO).

 

Methods

 

5 subjects with no retinal pathology or evidence of eye disease were identified prior to imaging. Reflectance imaging with a 790nm super luminescent diode was used to identify the vascular structures of interest. One gram of fluorescein mixed with 4oz of orange juice was administered orally. Single-photon fluorescence images were then collected at the previously identified areas using a 488nm solid state laser for excitation and an emission filter centered at 525nm with a 45nm bandwidth over a 1° field of view. Imaging was repeated at 15 minute intervals until signal extinction. 3 subjects were also imaged after IV fluorescein administration.

 

Results

 

Averaging 120 fluorescence images revealed the retinal microvasculature. Measurable fluorescence signal was observed as early as 8 minutes and as late as 2 hours after administering fluorescein orally. Although absolute fluorescence signal varied across patients, the best images were obtained between 15 and 45 minutes after administration. On the AOSLO, oral fluorescein provided comparable image quality to that of IV fluorescein. Time to signal extinction with IV fluorescein was shorter, probably due to quicker redistribution of the dye. No side effects from either oral or IV administration of fluorescein were observed.

 

Conclusions

 

Fluorescein angiography is an invaluable tool in the management of ocular disease. Coupled with AOSLO, it permits a detailed examination of the capillary bed of the inner nuclear layer when compared to conventional IV FA. Furthermore, FAOSLO with oral fluorescein is a safer alternative to IV angiography and provides a longer imaging time window. High resolution imaging of the retinal microvasculature with FAOSLO will not only help to further understand vascular micropathology but will also guide early intervention in management of vascular diseases.

 

 

Fig 1. Retinal vasculature as seen on: A.fundus photography B.with IV Fluorescein C.magnified view of a vessel (top arrow in B) D.FAOSLO image with IV fluorescein corresponding to frame C E.magnified view of a vessel (bottom arrow in B) F.FAOSLO image with oral fluorescein corresponding to frame E

 

 

Fig 2. Comparison of mean intensity over time on averaged fluorescence images

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 688 retina • 436 blood supply