Lowering internal eye pressure is currently the only way to treat glaucoma, researchers said.
Now, a tiny eye implant could enable patients to take more frequent readings from the comfort of home. Daily or hourly measurements of eye pressure could help doctors tailor more effective treatment plans.
Internal optic pressure (IOP) is the main risk factor associated with glaucoma, which is characterized by a continuous loss of specific retina cells and degradation of the optic nerve fiber, researchers said.
The mechanism linking IOP and the damage is not clear, but in most patients IOP levels correlate with the rate of damage.
Reducing IOP to normal or below-normal levels is currently the only treatment available for glaucoma. This requires repeated measurements of the patient's IOP until the levels stabilize.
The trick with this, though, is that the readings do not always tell the truth, researchers said.
Like blood pressure, IOP can vary day-to-day and hour-to-hour; it can be affected by other medications, body posture or even a neck-tie that is knotted too tightly.
If patients are tested on a low IOP day, the test can give a false impression of the severity of the disease and affect their treatment in a way that can ultimately lead to worse vision.
The new implant was developed as part of collaboration between Stephen Quake, a professor of bioengineering and of applied physics at Stanford University, and ophthalmologist Yossi Mandel of Bar-Ilan University in Israel.
It consists of a small tube - one end is open to the fluids that fill the eye; the other end is capped with a small bulb filled with gas. As the IOP increases, intraocular fluid is pushed into the tube; the gas pushes back against this flow.
As IOP fluctuates, the meniscus, the barrier between the fluid and the gas moves back and forth in the tube. Patients could use a custom smartphone app or a wearable technology, such as Google Glass, to snap a photo of the instrument at any time, providing a critical wealth of data that could steer treatment.
For instance, in one previous study, researchers found that 24-hour IOP monitoring resulted in a change in treatment in up to 80 percent of patients.
The implant is currently designed to fit inside a standard intraocular lens prosthetic, which many glaucoma patients often get when they have cataract surgery, but the scientists are investigating ways to implant it on its own.
The research was published in the journal Nature Medicine.

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