Restoring a functional level of vision to people who are blind has been a dream of medicine for centuries. Although we are still far from restoration of high-resolution vision, bionic eye technologies are overcoming crucial bottlenecks and are slowly moving from the laboratory into the clinic and onto the free market.

Sight Restoration Technologies

Bionic Vision is not limited to computer interfaces but instead encompasses a wide range of vision restoration and/or rehabilitation techniques.

Electronic Neuroprostheses

Neuroprostheses, better known as "implants", have been a common focus of research and investments into curing blindness. These devices come in the form of a miniature chip which is placed into a specific location of the retina (retinal implants

) or the brain (cortical implants

Retinal implants function to replace damaged photoreceptor cell activation. However, if the disease has significantly interrupted the early visual pathway (i.e. the retina, optic nerve, or lateral geniculate nucleus), cortical implants may be the only option.

Optogenetic Neuroprostheses

Optogenetics is a technique that uses a combination of optical and genetic methods to restore vision loss. Once light-sensitive proteins are introduced to the area of the damaged photoreceptors, retinal neurons can be stimulated by using a specific range of light intensities and wavelengths.

Two types of optogenetic strategies have been studied: ion channel therapies and G-protein coupled receptor (GPCRs) therapies. Ion channel therapy research focuses on improving temporal sensitivity for vision. While slower than ion channels, GPCR therapies have demonstrated much promise for vision restoration given their higher sensitivity to light activation. Both have been used to study and treat retinal dystrophies and degenerative diseases.

There are a few companies in the process of developing accurate optogenetic studies for future use. The GenSight PIONEER preliminary trial combines optogenetic therapy with biomimetic goggles. These specially designed goggles help to compensate for spatiotemporally related visual distortions associated with optogenetic treatment.

Gene-Based Therapies

When there is a mutation of a gene, the synthesis of proteins that follows is affected such that there can be an increase or inhibition of function for that gene. Inhibiting the function of a protein within the retina can lead to diseases that cause blindness. Gene therapy and gene editing are two current genetic approaches being studied to prevent the spread of retinal disease and possibly restore vision.

Gene therapy involves using recombinant DNA to encode the desired DNA into a plasmid which is delivered into the cell by a vector. This is meant to cause the expression of the desired gene throughout the retina, and restore cellular function. A limitation of gene therapy is that it can only function to supplement the expression of a gene, not eliminate or suppress the desired genetic expression. There has been significant progress in gene therapy for treating Leber congenital amaurosis, which shows promise in treating more frequent diseases in vision such as AMD and RP.

Cell Therapy

Once they are successfully injected or transplanted into the retina, stem cells have the ability to form all cell types necessary for retinal regeneration. There are two types of stem cells that can do this: embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). ESCs and iPSCs can mature into pluripotent stem cells, and pluripotent cells are then able to differentiate into bipolar or photoreceptor cells.

Inserting stem cells within the retina may be conducted through an injection process or a transplantation. There have been multiple trials over the past ten years testing the usefulness of stem cell therapy within the retina, mostly yielding promising results. Research has focused on studying the effectiveness of stem cell therapy in creating retinal pigment epithelium (RPE) cells and photoreceptor cells. Data suggest that iPSC transplants can produce RPE cells and have potential to restore vision or even slow the progression of disease for AMD patients. There are currently no clinical trials that have demonstrated the effectiveness of stem cell therapy for photoreceptor cells.

Sensory Substitution

Sensory substitution devices change visual information to auditory or tactile information. What is most notable about these solutions is that they do not require invasive surgery for use, instead relying on the plasticity of other sensory modalities to adapt new strategies to compensate for vision loss. When paired with extensive training, people who are blind or have low vision can improve performance in navigation, object recognition, and more.

Devices in this category include the vOICE (visual to auditory) and BrainPort (visual to tactile).