​It may be able to detect disease accurately in a minute, cost a fraction of current tests

It can take several tests to detect glaucoma, but in future, doctors could use a handheld device to get an accurate reading within a minute.

Developed by researchers from the Singapore National Eye Centre (SNEC) and Singapore Eye Research Institute (Seri), the device tests the constriction of the pupil in reaction to red and blue lights.

The method also has the potential to spot early-stage glaucoma, which currently is most accurately detected through optical coherence tomography - a test that uses light waves to take cross-section pictures of the retina.

Glaucoma, which affects around 3 per cent of people over 40 here, can be difficult to diagnose early because patients typically do not suffer noticeable vision loss until the condition becomes severe.

It is caused by a build-up of pressure in the eye - usually from fluid - that damages the optic nerve.

However, blindness can largely be prevented if the disease is detected and treated earlier.

Professor Dan Milea, a senior clinician from the neuro-ophthalmology service at SNEC who helped to develop the device, hopes that having a simpler and cheaper test will enable more people to get treated earlier.

The Singapore Epidemiology of Eye Diseases Study had previously found that nearly three-quarters (72.1 per cent) of 272 patients with primary glaucoma were previously undiagnosed.

"There is a high need for a simple, objective, cost-effective test (but) there is none at the moment," Prof Milea said.

The handheld device, which is still under trial, is as light as a smartphone and is projected to cost patients a fraction of current tests such as optical coherence tomography and the visual field test, which each cost between $35 and $75, added Prof Milea.

In addition, unlike current tests, the device does not require a technician to operate it and it can be used at general practitioners' clinics, optical shops and even at home, according to Dr Raymond Najjar, a senior research fellow at Seri's visual neurosciences research group.

Researchers said the handheld device's accuracy in detecting glaucoma is similar to a larger version of the device, which showed encouraging results.

A 2015 to 2017 study on the larger device found that early-stage primary open-angle glaucoma was linked to reduced constriction of the pupil when it was exposed to moderate and high intensities of blue and red lights, compared with the pupils of people without glaucoma.

This finding added to previous knowledge that such a method works in detecting the middle and late stages of the disease.

The study involved 46 patients with glaucoma and 90 who did not have it, and was conducted by researchers from SNEC, Seri and Duke-NUS Medical School.

It was published last month in Ophthalmology, the journal of the American Academy of Ophthalmology.

Glaucoma patient Lee Chee Wee, 60, thinks such a device would have made the process of detecting his disease much easier.

"The (current) tests are not really user-friendly for the elderly, like the visual field test where you have to press a button whenever a blinking light appears," said the university professor, whose glaucoma in his right eye was detected only in the advanced stages more than 10 years ago.

He underwent surgery to lower pressure in his eye two years ago.

Researchers are in talks with companies to develop the handheld device commercially. It also has the potential to detect retinal diseases such as diabetic retinopathy.