The eye is a complex organ consisting of multiple structures and tissue types. The inner-most layer (depicted in yellow) is the retina, which acts as the initial sensor for light passing into the eye through the focusing tissues of the eye – the cornea and lens. Signals from the retina are processed to some degree and then conducted along the optic nerve, which exits the back of the eye and connects to the brain. The choroid (depicted in red) provides a blood supply to the outer portion of the retina – the retinal pigmented epithelium (RPE) and photoreceptors. Damage to the retina from injury or disease is generally irreversible, leading to permanent loss of vision.
The retina is an outgrowth of the brain, and the only part of the central nervous system that can be non-invasively visualized. At the center of the retina, a sub-structure known as the macula (shown here as a small circle within each cross-section) is densely populated with cone-type photoreceptors. This region is responsible for high-acuity central vision and color vision, and can become damaged as a result of diseases such as age-related macular degeneration or late-stage retinitis pigmentosa. Our optic vesicle technology mimics development of the retina.
The retina contains a series of interconnected neurons, including photoreceptors, bipolar cells, and ganglion cells. Photoreceptors are highly metabolically active cells, requiring continual support from the adjacent retinal pigment epithelium (RPE) cells and underlying choroidal blood circulation. There are two basic types of photoreceptor, rods and cones, which have different light-adsorption properties necessary for high-acuity central vision and color discernment (cones) and low-light and peripheral vision (rods).