Many people suffer from various forms of retinal damage, such as retinitis pigmentosa, retinal detachment, diabetic retinopathy, and macular degeneration, which can lead to diminished sight and blindness. And, as the age of the general population increases, the number of people suffering from diminished sight due to these causes increases.
Several devices have been developed to attempt to restore vision loss due to retinal damage. For example, silicon-chip based photovoltaic devices, which are attached to a portion of a retina, have been developed to stimulate rods and cones within the retina. Although such devices may provide some stimulation, the devices suffer from several drawbacks. In particular, the devices are relatively large (e.g., on the order of square millimeters). As a result, when placed on a retina, the devices block significant portions of light that would otherwise reach rods and cones located behind the devices. Another problem associated with these devices is that they are placed on a surface of the retina, which is delicate; thus, the retina surface may tear or otherwise become damaged when the devices are attached to the retina.
Other, silicon-chip based devices, which are implanted subretinally have also been developed to attempt to improve vision in those suffering from retinal damage. Mild improvement of electrical response to light has been observed using these devices. However, several problems have also been observed. Specifically, because the devices are relatively large, once the devices are attached to the retina, oxygen is blocked from reaching cells adjacent to or proximate the devices. In addition, implantation of the devices is thought to further damage the retinal tissue.
Accordingly, improved devices and methods for increasing electrical stimulation of photoreceptors and/or other portions of a retina within an eye are desired.