Navigation Links
Researchers develop a halometer that tests alterations in night vision
Date:3/24/2011

This press release is available in French and Spanish.

Researchers from the Department of Optics of the University of Granada, belonging to the Laboratorio de Ciencias de la Visin y Aplicaciones, have developed a programme for testing alterations in night vision, and the tool required to implement it, which has been named "halometer".

This instrument consists on a software named Software Halo v1.0, and a computer where the mouse is used as a response button, and a chin cup with a forehead holder to fix the observer's position. Software Halo v1.0 was initially presented as freeware available on LabVisGra's website at http://www.ugr.es/local/labvisgr and at the University of Granada's institutional repository at http://digibug.ugr.es/handle/10481/5478. Nevertheless, it was recently released by the Free-Software Bureau of the University of Granada so, it has become a scientific freeware application.

This software was developed by a group coordinated by Rosario Gonzlez Anera, receiving technical support of the Granadian company Seven Solutions and of an ophthalmological clinic set in Madrid and named Novovision. The research group was integrated by researchers Jos Juan Castro, Carolina Ortiz and Aixa Alarcn, and receives fundings from the regional government of Economy, Innovation and Science of the Junta de Andaluca.

Low-Light Conditions

Before the test, researchers fix the observer's position with a chin cup and a forehead holder at an adequate distance from the monitor where the test will be displayed and considering the angular diameter that light stimuli must have. The test is performed under low-light conditions (in a dark room) and, before the test, patients are given some minutes to adapt to darkness.

This test involves showing a bright light stimulus to the subject against a dark background and, progessively showing different peripheral light stimuli with lower brightness around the central (Figure 2), at random, in different positions and at different distances. Subjects' task is to press the buttom of a mouse every time they detect a peripheral stimulus. Once the test ends, the software makes an estimation of a parameter named "Visual Disturbance Index" that, together with the results graphic, determines the type and intensity of visual disturbance.

This index scores from 0 to 1, so the higher is this index, the stronger is the influence of the halo or any other visual disturbance perceived by the observer. Therefore, the lower is the subject's ability to detect the peripheral stimuli displayed around the main stimulus that causes such disturbances.

One of the advantages of the halometer developed at the University of Granada is that it allows to configure such test parameters as:

  • Special parameters: the radius of the central stimulus and the peripheral stimuli can be modified. Furthermore, the number of semi-major axes where the peripheral stimuli will be displayed can be fixed, as well as the maximum radius maximum distance between these stimuli-, and the number of stimuli per semi-major axe.

  • Temporary Parameters: the software allows to set some exposure time for adaptation to darkness and to the brightness of the central stimulus. Furthermore, others parameters as the exposure time to the stimulus and the time elapsed between a stimulus and the next one can also be set.

  • The software also allows to set the color and brightness of central and peripheral stimuli, and the weight and number of times each peripheral stimulus is shown.

This test has been tried with different observer groups consisting of people operated on cataract or submitted to refractary eye surgery, with normal observers and patients with different eye pathologies as AMD (Age-related Macular Degeneration) and unilateral keratitis. The results obtained showed that, in the case of patients with keratitis, the visual disturbance index for the healthy eye was found to be lower than that for the unhealthy eye, and even lower under binocular vision conditions. However, visual disturbance indexes proved to be higher in the case of patients operated on cataracts, showing a higher influence of halos and, therefore, lower detection capacity. Patients operated with LASIK refractory eye surgery also presented high vision disturbance indexes in comparison to normal observers.

The results obtained with this halometer and the new software have been presented in different national and internacional conferences as the IX Reunin Nacional de ptica, Galice and the Wavefront Confress 2009. furthermore, a research article has been published in the international journal Applied Optics describing the results obtained with patients operated with refractory eye surgery. It has also been recently admitted for publication in the prestigious scientific journal Journal of Biomedical Optics, where the results obtained with patients with different eye pathologies are described.


'/>"/>

Contact: Jos Juan Castro
jjcastro@ugr.es
34-958-241-902
University of Granada
Source:Eurekalert  

Related medicine news :

1. Researchers map all the fragile sites of the yeast Saccharomyces cerevisiaes genome
2. UH Case Medical Center researchers publish promising findings for advanced cervical cancer
3. Researchers discover new way to kill pediatric brain tumors
4. Researchers Who Discovered First Genes for Stuttering will Present Findings to the National Stuttering Association
5. Researchers create drug to keep tumor growth switched off
6. Urine protein test might help diagnose kidney damage from lupus, UT Southwestern researchers find
7. GUMC researchers say flower power may reduce resistance to breast cancer drug tamoxifen
8. Clemson researchers develop hands-free texting application
9. Researchers find biomarkers in saliva for detection of early-stage pancreatic cancer
10. Researchers chart genomic map spanning over 2 dozen cancers
11. Researchers discover second protective role for tumor-suppressor
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Researchers develop a halometer that tests alterations in night vision
(Date:6/23/2017)... , ... June 23, 2017 , ... Everybody has their ... while others prefer to read it, and some people don't like it at all. ... Here's what they found: , Erotic literature can give readers a taste of their ...
(Date:6/23/2017)... ... June 23, 2017 , ... 21 Middle East and South Asia Leaders Selected ... from government, business and civil society in 11 countries across the Middle East and ... in a transformative exchange of knowledge and ideas with the leading minds in their ...
(Date:6/23/2017)... ... 23, 2017 , ... Ulster University, Magee Campus in Northern Ireland is hosting ... pm to present to graduate students exciting new and innovative hope research based on ... by The Health Improvement Service of the Western Health & Social Care Trust (WHSCT) ...
(Date:6/23/2017)... ... June 23, 2017 , ... Moore Insurance, ... area with access to asset protection and financial planning services, is teaming up ... improving the lives of children with cancer and other chronic diseases. , The ...
(Date:6/22/2017)... ... June 22, 2017 , ... ... from the American Heart Association (AHA) to launch a Rheumatic Heart Disease Center, ... prevention and diagnosis of rheumatic heart disease (RHD) in high-risk, financially disadvantaged countries ...
Breaking Medicine News(10 mins):
(Date:6/16/2017)... , June 16, 2017  Exactly 50 years ago ... off what later became known as the San Francisco "Summer ... ) is unveiling two radical innovations in strategic market research ... This announcement marks the beginning of Northern Light,s "Summer of ... ...
(Date:6/12/2017)... , June 12, 2017 Kineta, Inc., a biotechnology ... Kineta Vice President of R&D and Head of ... Pandemic Preparedness for the Northwest and Beyond meeting ... on June 14, 2017 from 8:30-10:30 AM PDT at the ... Dr. Bedard will be joined by other ...
(Date:6/8/2017)... MAITLAND, Fla. , June 8, 2017  Less ... ransomware attack that hit more than 200,000 companies, including hospital ... is being heralded as one of the largest online ... technology in the healthcare market, it is imperative that ... can protect their data from this — and many ...
Breaking Medicine Technology: