Navigation Links
'Twinkle after-effect' can help retinal patients detect vision loss quickly and cheaply

Boston, MAScientists 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 weeks 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 ophthalmologists 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 wasnt 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.


Contact: Patti Jacobs
Public Library of Science

Related biology news :

1. Emory Eye Center Implants Its First Retinal Chips In Patients With Retinitis Pigmentosa
2. Six previously blind patients detect light, motion, identify objects with retinal prostheses
3. Retinal scans eyed for New Mexico show cattle
4. New gene reduces retinal degeneration in fruit flies
5. Prosthetic retinal cells let blind mice see light
6. Transplanted photoreceptor precursor cells restore visual function in mice with retinal degeneration
7. Adding Radiation Therapy To Chemotherapy Improves Survival In Patients With High-risk Breast Cancer
8. HIV Patients May Be at Risk of Heart Problems When Taking Protease Inhibitor Drugs
9. Study identifies predictors of HIV drug resistance in patients beginning triple therapy
10. Potential Cure for Lymphoma in HIV patients
11. Implanted Devices Detect High-Risk Heart Failure Patients
Post Your Comments:
(Date:10/26/2015)... October 26, 2015 ... adds Biometrics Market Shares, ... as well as Emerging Biometrics Technologies: ... to its collection of IT and ... . --> ...
(Date:10/26/2015)... Calif. , Oct. 26, 2015  Delta ID ... biometric authentication to mobile and PC devices, announced its ... smartphone, the arrows NX F-02H launched by NTT DOCOMO, ... NX F-02H is the second smartphone to include iris ... technology in ARROWS NX F-04G in May 2015, world,s ...
(Date:10/23/2015)... BERLIN and GOLETA, California ... the HFES conference, BIOPAC and SensoMotoric Instruments (SMI) announce ... and eye tracking data captured during interactive real-world tasks ... plug and play integration of their established wearable solutions ... researchers to synchronize gaze behavior captured with SMI ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... -- PharmAthene, Inc. (NYSE MKT: PIP) announced  today that its ... (Rights Plan) in an effort to preserve the value ... 382 of the Internal Revenue Code (Code). ... its NOLs could be substantially limited if the Company ... of the Code. In general, an ownership change occurs ...
(Date:11/25/2015)... , November 25, 2015 ... cat and human plaque and pave the way for more ... problems in cats     --> ... most commonly diagnosed health problems in cats, yet relatively little ... now. Two collaborative studies have been conducted by researchers from ...
(Date:11/25/2015)...  Neurocrine Biosciences, Inc. (Nasdaq: NBIX ) announced ... of Neurocrine Biosciences, will be presenting at the 27th ... York . .   ... minutes prior to the presentation to download or install ... be available on the website approximately one hour after ...
(Date:11/25/2015)... , ... November 25, 2015 , ... ... the Organization of Black Aerospace Professionals (OPBAP) has been formalized with the signing ... AMA team leaders met with OPBAP leaders Capt. Karl Minter and Capt. Albert ...
Breaking Biology Technology: