Glaucoma risk measured with advanced contact lens

A miniaturised pressure sensor embedded into a contact lens is proving to be a hi-tech solution for improved monitoring and management of patients with glaucoma.

The eye disease affects 65 million people worldwide and is the leading cause of irreversible blindness. It is characterised by increased pressure within the eyeball which gradually damages the optic nerve.

Dr Kaweh Mansouri, Hamilton Glaucoma Center, University of California, San Diego said management of glaucoma was usually based on a single measurement of intraocular pressure (IOP), the only treatable risk factor for the condition.

“However we now have a way to continuously monitor IOP during a 24 hour period, on an out-patient basis, at-home, and while the patient is going about their normal routine,” he added. “The information we gained from this monitoring resulted in a more personalised treatment plan for these patients.”

While there is no cure for glaucoma, better management of the condition can slow progression of the disease and prevent further vision loss.

Speaking at the Asia Pacific Academy of Ophthalmology (APAO) Congress in Sydney, Dr Mansouri said, “We found that we were missing the true picture of IOP spikes and nocturnal variations in patients whose pressure appeared well controlled in routine office testing.”

The tiny platinum and titanium sensor in the contact lens measures IOP fluctuations by detecting any corresponding changes in the curvature of the cornea.

The measurements are picked up by an antennae located in a patch around the patient’s eye, and transmitted to a pocket sized recording device on the patient. The data can then be downloaded to the doctor’s desktop at the end of the 24-hour period.

In a study group of 30 patients with open-angle glaucoma, the most common type of glaucoma, more than 70 per cent recorded their peak IOP during the sleep period.

In two-thirds of the patients, the peak pressure was clinically significant to their daytime reading – initiating an immediate change in how the patients were being treated.

Dr Mansouri said 24 hour monitoring meant that patient care could be optimised to prevent further damage to the optic nerve and subsequent vision loss.

“There is certainly potential for this type of monitoring to change clinical care of glaucoma patients in much the same way that continuous or home monitoring of blood pressure or blood glucose has done for patients with hypertension or diabetes,” he added.

Dr Mansouri said some patients required a change in their eye drops or different timing of their current medication, while others required more invasive treatment such as laser or surgery.

Two patients with the co-existing condition of dry eye found they could not tolerate the device for the full 24 hours, but otherwise side effects were infrequent and minor.

“We think this specialised contact lens would be indicated for use in most, if not all, glaucoma patients and possibly some glaucoma suspects as well,” he said.

Dr Mansouri’s early data with 15 patients was published online 7 January 2011 in Br J Ophthalmol.

(Source: Asia Pacific Academy of Ophthalmology Congress: Br J Ophthalmol)

More information

For more information on glaucoma, including the effect of nutrition on eyes, as well as some useful animations and tips to keep eyes healthy, see Glaucoma.