Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

“Twinkle After-Effect" Can Help Retinal Patients Detect Vision Loss Quickly and Cheaply

29.10.2007
Scientists at Schepens Eye Research Institute, an affiliate of Harvard Medical School, have discovered a simple and inexpensive way for patients with retinal and other eye disease to keep track of changes in their vision loss.

In a study published in this week’s PLoS ONE (October 24, 2007) they demonstrate that a compelling visual illusion known as the induced twinkle after-effect (TAE) can accurately identify the location and breadth of actual blind spots in people with retinal disease. The twinkle after-effect is a “twinkling” that people can see in a blind spot when they stare at a blank screen after staring at a noisy visual target such as a detuned television screen.

“Our hope is that we can make this simple technique available online or on a DVD,” says Dr. Peter Bex, associate scientist at Schepens Eye Research Institute and the principal investigator of the study. “This will be particularly helpful with patients who have glaucoma, diabetic retinopathy or macular degeneration where early detection of changes in vision can impact the effectiveness of treatments.”

According to Bex, many people fail to seek help when they develop blind spots in their vision, because their brains automatically compensate or “fill in” the missing information in their visual field. Since everyone has a blind spot where the optic nerve meets the retina, this perceptual “fill in” process is useful for normally sighted people, allowing them a complete visual image. “But this innate process can mask the effects of serious disorders such as diabetic retinopathy and glaucoma and keep sufferers from seeking help until the vision loss is very serious or they bump into objects they can no longer see.”

The traditional gold standard method for detecting blind spots (scotomas) is very expensive and time consuming and must be done in an ophthalmologist’s office. The technique known as retinal specific microperimetry is a diagnostic tool that costs nearly 50 thousand dollars and requires specialized training to apply.

In 1992 scientists became aware of what they eventually named the “twinkle after effect.” They discovered that when someone looks at a television screen filled with static noise while covering part of their visual field with a small patch, the formerly patched area is left with a twinkling sensation after the noise is turned off and the person looks at a blank screen. The rest of the visual field does not experience the twinkling effect, which was described by one patient as resembling a moving cumulous cloud. “While this discovery was intriguing, it wasn’t clear how it could be used for patients,” says Bex.

In the past several years, Bex and his team began to understand its potential. “We theorized that if people with blind spots stared at a noisy screen, the blind areas would “twinkle” when the screen was turned off and their eyes focused on a blank screen. These ‘twinkling’ blind spot areas could then easily be mapped,” he says.

To test their theory, Bex and his team asked eight patients with macular degeneration to undergo the retinal specific microperimetry test and his “twinkling after-effect” test. The team provided a blank touch screen--after the noisy screen--so patients could outline the twinkling areas with their finger.

The team found that the results of the two tests matched in 75 percent of cases, and visual defects could be detected in areas that are not accessible to conventional microperimetry, confirming his belief that TAE could be used diagnostically. “This tool cannot replace the more sophisticated technique but we believe it is a powerful, simple tool that patients can use daily in the privacy of their home to detect any changes in their vision,” he says. “If a patient detects a change, his or her physician can then study it more closely and offer therapy.”

While the results of this small study are very encouraging, Bex says the next step is to do a larger clinical study.

Ultimately Bex sees this type of test being free to the public on the Internet or distributed through a public health entity. “We really believe this could have a great impact on the visual health of the community,” says Bex.

Other members of the study team are Michael D. Crossland and Steven C. Dakin of the UCL Institute of Ophthalmology, London, UK.

Schepens Eye Research Institute is an affiliate of Harvard Medical School and the largest independent eye research institute in the world.

Andrew Hyde | alfa
Further information:
http://www.plosone.org/doi/pone.0001060

More articles from Health and Medicine:

nachricht The end of pneumonia? New vaccine offers hope
23.10.2017 | University at Buffalo

nachricht Scientists track ovarian cancers to site of origin: Fallopian tubes
23.10.2017 | Johns Hopkins Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>