Abstract
Purpose :
The subretinal space is a target location for the delivery of novel cell and gene based therapeutics in to the eye. Gaining access to the subretinal space via the transscleral route may offer advantages over the conventional transretinal route. However, external visualization during the transscleral approach poses a challenge as the sclera is opaque and thus direct visualization and OCT imaging are hampered. Here, we aimed to develop a common-path swept source optical coherence tomography (CP-SSOCT) fiber probe sensor coupled with a precise translation stage to guide external access to the subretinal space by providing information regarding retinal and choroidal layers with micron accuracy.
Methods :
The CP-SSOCT sensor with a high-index epoxy lens was secured inside a 30-gauge needle. A three-way stopcock facilitated an additional port for a syringe to be connected for injection of material. The needle and stopcock were mounted on a precise translation stage. The device was tested on ex-vivo bovine eyes and in-vivo porcine eyes with the device fixed on an articulated arm. A-scan images of bovine and porcine retinas were obtained to determine whether retinal layers could be identified and measured.
Results :
The needle was positioned perpendicularly to the scleral surface just anterior to the ocular equator. A-scan images of bovine and porcine retinas were acquired as the needle was advanced. When the needle made contact with the eye, the boundaries and layers of the retina could be identified. Using the peak and envelop information acquired, the retinal pigment epithelium (RPE), photoreceptor inner and outer segment (IS/OS) junction and the inner limiting membrane (ILM) could be identified on the A-scan images. The bovine peripheral retinal thickness measured approximately 300 microns which is comparable to that measured by a reference-based OCT imaging system.
Conclusions :
The CP-SSOCT fiber sensor provides anatomical information regarding retinal layers and measurements via an external approach. This technique enables precise needle insertion for transscleral injection of materials into the subretinal space.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.