Visualization of Multiple Retinal Capillary Beds using Offset Pinhole Adaptive Optics Scanning Light Ophthalmoscopy

Abstract

 

Purpose

 

To image retinal capillary beds at different retinal layers in healthy and diseased retinas using an offset pinhole adaptive optics scanning light ophthalmoscope (AOSLO).

 

Methods

 

Retinal capillary plexuses at different depths were imaged at various retinal locations in 2 healthy controls and 3 patients (PDR, HRVO, BRVO) using an offset pinhole AOSLO with an imaging wavelength centered at 790nm. Imaging locations on the healthy controls were located at 5° temporal, nasal, and superior to the fovea. Region of interests with vasculopathic structures were pre-identified on fundus pictures on the patients. Image sequences were acquired using 1° or 1.5° field of view at a frame rate of 15Hz. After sinusoidal distortion and eye motion were removed, averaged images and motion contrast perfusion maps were generated at different retinal depths.

 

Results

 

Multiple retinal capillary beds were clearly visualized in both controls and patients using offset pinhole AOSLO. Three distinct capillary beds were resolved at all retinal locations imaged in the controls. From the 3 patients with retinopathies, vasculopathic structures such as microaneurysms and tortuous blood vessels were observed at different retinal depths. Fig 1 demonstrates a fusiform microaneurysm located in the outer retina in a patient with HRVO. This technique enabled precise depth location of normal and pathologic structures with high lateral resolution that is often a limiting factor when attempting similar stratification using optical cohernece tomography

 

Conclusions

 

Offset pinhole AOSLO provides noninvasive and direct visualization of multiple retinal capillary beds at different depths, as well as the ability to isolate retinal vasculopathic structures at different retinal capillary beds. This imaging technique provides a better understanding of normal and pathological retinal vasculature development.  

 

Fig 1 demonstrates a fusiform microaneurysm located in the outer retina capillary layer in a patient with HRVO. The thru focus technique is able to distinguish the precise level of the lesion