This is not just a research interest. At age two I lost the sight in my right eye to retinoblastoma. I have lived with monocular vision my entire life. I want to understand where the science and engineering of ocular prosthetics actually stands and where the hardest problems remain unsolved.
Retinoblastoma is a rare form of eye cancer that develops in the retina, most commonly in children under five. Treatment options depend on the stage and extent of the tumour. In cases where the cancer is too advanced to save the eye, enucleation (surgical removal of the eye) is performed to prevent the cancer spreading. This is the situation I was in at age two.
After enucleation, the orbit (eye socket) is fitted with an orbital implant to maintain the shape of the socket. A prosthetic eye (ocular prosthesis) is then custom-made to sit in front of the implant. Modern prosthetic eyes are typically made from acrylic and are hand-painted to match the patient's other eye. They provide a cosmetic restoration but no visual function. That gap is what I find most interesting from an engineering perspective.
The current state of ocular prosthetics divides into two distinct categories:
These are the traditional prosthetic eyes most people picture. They are non-functional in terms of vision but have advanced considerably. Modern hydroxyapatite (HA) orbital implants are porous, which allows blood vessels to grow into the implant over time. This vascularisation means the implant integrates with surrounding tissue and can be connected to the eye muscles for better motility, meaning the prosthetic eye moves more naturally in response to the other eye. Some implant designs also include a peg system that mechanically connects the prosthetic to the implant to further improve movement coordination.
Custom acrylic prosthetics are hand-crafted and painted by specialist ocularists. The quality of the cosmetic result depends heavily on the skill of the ocularist and the quality of fitting. Digital fabrication techniques including 3D scanning and digital painting are beginning to enter the field, with some studies showing comparable cosmetic outcomes and significantly reduced production time.
This is the frontier of the field. Visual prosthetics attempt to restore some form of functional vision by directly stimulating the visual pathway electrically. Several approaches are being investigated:
The core problem in visual prosthetics is resolution. The human retina contains approximately 120 million photoreceptors. Even the most advanced implants currently stimulate on the order of a few hundred electrodes. The resulting visual percept is described by patients as sparse phosphenes (flashes of light) rather than coherent imagery. Bridging this gap requires either dramatically increasing electrode density or finding smarter stimulation strategies that exploit the remaining neural circuitry.
Key engineering challenges in the field include:
My immediate goal is to build a deep understanding of the field: what has been achieved, where the primary limitations lie and what the current research directions are. As someone with a background in embedded systems and electronics, the hardware side of this problem is what interests me most.
Specifically, I want to investigate:
I am realistic about the timescales involved. This is not a project I will complete in a summer. Research in neural interfaces takes years and requires multidisciplinary teams. But I want to build a serious understanding of the field at the level where I could eventually contribute to it, whether through research during a postgraduate degree, through a placement at a medical device company or through independent work.
The starting point is a literature review: reading the key papers, understanding the state of the art and identifying the specific technical problems that seem most tractable from an electrical engineering perspective. I will document that process here as it develops.
If my constraints contributed to the tools I build for myself, I see no reason why they cannot eventually contribute to tools that help other people in similar situations. That is the direction I want to move in.