Distribution of Gold Nanorods Monitored With Spectral-Domain Optical Coherence Tomography (SD-OCT) After Intravitreal Injection

Abstract

 

Purpose:

 

Gold nanorods (GNRs) have the potential to be useful for contrast enhancement within optical coherence tomography images. However, the distribution of GNRs in the eye after intravitreal injection has not been documented. The goal of this study was to monitor the location of GNRs using SD-OCT and confirm the location with transmission electron microscopy (TEM).

 

Methods:

 

GNRs were prepared using a well established seed-mediated, surfactant directed synthesis. An aspect ratio of ~4.5 was chosen such that the surface plasmon resonant response matched the center wavelength used in our SD-OCT system (_spr = 840 nm). An intravitreal injection of 2 µl of the GNR solution was administered in one eye of eight healthy adult male C57Bl/6 mice; a sham intravitreal injection of 2 µl of phosphate buffered saline (PBS) was administered to four additional mice. Raster 3D SD-OCT images of the retina, lens and vitreous were acquired before and after injection using identical scanning protocols (1.5x1.5x2 mm scan, 250x250x1024 pixels; Bioptigen, Inc, Durham, NC). Six mice (2 sham, 4 GNR) were imaged for 8 days following injection and then sacrificed. The remaining mice were followed for 30 days. TEM was performed on the retinas of six mice and lenses of three mice.

 

Results:

 

An increase in intensity was seen in the vitreous and posterior lens in eyes injected with GNRs, and this was not observed in the eyes that received a sham injection (Figure, a). GNRs were seen by TEM in the vitreous, decorating the hyaloid canal, adherent to the lens, within the lens and in microglia within the retina (Figure, b).

 

Conclusions:

 

GNRs injected into the vitreous stay in the vitreous for at least 30 days after injection, but are also present in the lens and retina. A change in backscattered intensity could be detected within SD-OCT images while the GNRs were present.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • vitreous • microscopy: electron microscopy