When its levels are slightly off-kilter, eye fluid can create pretty big problems for our vision. When blockages occur they can lead to a build up in pressure that destroys the optic nerve and causes blindness, a condition we know as glaucoma. In contrast, a lack of fluid can cause the eye to cave in and stop functioning, a disease known as phthisis bulbi. Currently, little can be done about these irreversible conditions once they take hold, but Fraunhofer researchers have a potential solution in the works by way of a microscopic pump that can be implanted in the eyeball to regulate ocular pressure.
Though there are treatments available for both glaucoma and phthisis bulbi, these only slow the progression of damage and loss of vision, rather than reverse their symptoms. In glaucoma patients, this can involve surgically stimulating the flow of fluids from inside the eyeball's anterior chamber, but around one in four patients suffer scar tissue which in turn causes drainage problems. For phthisis bulbi patients, treatment sees fluid in the eye regularly topped up through injections, an uncomfortable process that still leaves the loss of vision inevitable.
Researchers at the Fraunhofer Research Institution for Microsysems and Modular Solid State Technologies (EMFT) are developing an implant that, once inserted into the eye, could regulate fluids and eye pressure without the need for these unpleasant procedures. The entire system uses a microscopic, silicon micro-membrane pump that measures just 7 x 7 x 1 mm (0.27 x 0.27 x 0.4 in). Combined with a sensor-based control, a battery and a telemetry module for relaying data, the system can produce up to 30 micro liters of fluid per second.
In doing so, it can keep the eye moist where it would otherwise begin to dry up in sufferers of phthisis bulbi. Fraunhofer says that the fluid levels can be set by a physician on an outpatient basis with much more precision than traditional treatments. Because the fluid would be maintained at healthy levels, the team is hopeful that the system would stop the progression of the disease and preserve the patient's eyesight.
When it comes to glaucoma, the pump could also drain intraocular fluid as it builds up and creates pressure. This would be done using the natural channels for fluid drainage from the eye to avoid the forming of scar tissue.
At present, the researchers are developing a functional model to demonstrate the system's feasibility in the lab. Eventually, they hope to build a version that incorporates an implantable sensor to allow the regulation of fluids to be automated.