New York, Oct 5 (IANS): Researchers have developed a new non-invasive optical imaging system that promises to improve diagnosis and treatments for dry eye disease which often causes irritation and blurred vision.

Dry eye occurs when there is instability in the inner layer of the tear film that protects the outside of the eye.

Today, most cases of dry eye are diagnosed using patient questionnaires, which may be subjective and cannot typically be used to identify the cause of the disease.

Objective methods for examining the tear film tend to be invasive and cannot track rapid changing dynamics, which are altered with every blink.

"Up to 60 per cent of ophthalmology office visits are due to dry eye, pointing to the need for a non-invasive and highly accurate device for diagnosis in the office setting," said research team leader Yoel Arieli from AdOM Advanced Optical Methods Ltd. in Israel.

"Our Tear Film Imager is the first device that can be used in the ophthalmology or optometry setting to image the tear film and distinguish its inner layers with nanometer resolution," Arieli said.

The researchers described the device's ability to perform spectral measurements across a large field of view in a matter of seconds in the journal Applied Optics.

The imager can acquire fast and consistent measurements from human eyes even when blinking, said the study which was performed at AdOM Advanced Optical Methods laboratory.

The new instrument uses an eye-safe halogen light to illuminate the eye and then analyzes the full spectrum of light reflection over time and space.

These spectral measurements are used to reconstruct the structures found in the front of the eye, allowing accurate measurement of the tear film inner layers, especially the aqueous sublayer.

This sublayer plays an important role in dry eye but has been difficult to analyze with other methods.

The Tear Film Imager has been used in two clinical studies in Israel and Canada, examining dry eye diagnosis with the device and dry eye treatments, which can be precisely evaluated with the imager.