Clinical Trials Logo

Clinical Trial Summary

The visual disorder of amblyopia affects 2% to 3% of the population. Amblyopia is a developmental condition that is characterized by reduced vision of the eye due to the presence of a sensory impediment during visual development, such as strabismus (ocular misalignment) or anisometropia (unequal refractive error), occurring early in life. Recent studies in humans and animals point towards a cortical locus for the processing deficit in amblyopia, revealing sensory deficits at the signal cell level that include reduced spatial resolution, reduced contrast sensitivity, and a reduced number of binocular neural cells. In the retina, however, no abnormalities have yet been reported.

Like in the brain blood flow in the retina is coupled to neuronal activity. This phenomenon has been measured by different study groups with non invasive techniques in the brain and retina. We therefore use a Zeiss fundus camera for the assessment of retinal vessel diameters. This so called retinal vessel analyzer (RVA) is a combination of a fundus camera connected to a high resolution video camera equipped with a software based analyzing system. An unprecedented reproducibility and sensitivity of retinal vessel diameter measurements is attained with this system. In addition this system allows real time analysis of retinal vessels as well as off-line determinations from video tape. A special provocation test, which minimizes risk and discomfort to the subject under study is applied through the illumination pathway of the fundus camera: Diffuse luminance flicker is used as a stimulus to augment intrinsic mechanisms by which the retina can vary the vascular supply, in correspondence with local variations of functional activity. This system allows to study the flicker response of retinal vessels, which is within a magnitude of 6 to 8%.

However, the exact mechanisms underlying this phenomenon are not fully understood. Especially in the eye it is not clear whether it is an exclusive metabolic effect within the retina and the surrounding blood vessels or dependent of central regulatory brain functions.

The purpose of the current study is to improve our understanding of the mechanisms underlying flicker evoked responses of retinal blood vessels in humans. It is not clear whether the retina of amblyopic eyes can regulate retinal blood flow in response to increased metabolic demands as induced during flicking light stimulation. A detail understanding of the metabolic and functional processes within the retina of patients with amblyopia is a prerequisite for further research to prevent amblyopia.


Clinical Trial Description

n/a


Study Design

Allocation: Non-Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Diagnostic


Related Conditions & MeSH terms


NCT number NCT00312390
Study type Interventional
Source Medical University of Vienna
Contact
Status Withdrawn
Phase N/A
Start date July 2003

See also
  Status Clinical Trial Phase
Recruiting NCT04238065 - A Clinical Trial of Caterna Virtual Reality Facilitating Treatment in Children With Amblyopia N/A
Completed NCT04432181 - Comparison of Deviation Types Among Astigmatic Children With Or Without Amblyopia
Terminated NCT02767856 - Regimens of Intermittent Occlusion Therapy for Amblyopia in Children N/A
Completed NCT02458846 - Efficacy of Visual Screening in Ontario N/A
Completed NCT01190813 - Levodopa for the Treatment of Residual Amblyopia Phase 3
Completed NCT01109459 - Multimodal Physician Intervention to Detect Amblyopia N/A
Completed NCT04313257 - Monocular Action Video Game Treatment of Amblyopia N/A
Completed NCT04315649 - Effect of 3D Movie Viewing on Stereopsis in Strabismus and / or Anisometropic Amblyops N/A
Completed NCT05223153 - OCT-A and Amblyopia
Recruiting NCT05522972 - Establishing New Treatment Approaches for Amblyopia: Perceptual Learning and Video Games N/A
Completed NCT01430247 - Vision Screening for the Detection of Amblyopia N/A
Completed NCT02200211 - Study of Binocular Computer Activities for Treatment of Amblyopia N/A
Recruiting NCT06429280 - Clinical Data Registry of Amblyopia Patients on Luminopia Treatment
Withdrawn NCT04959422 - Assuring Ophthalmologic Follow up N/A
Active, not recruiting NCT05612568 - 5 Years of Eye Screening for ARF in Children Aged <3 Years in Flanders
Recruiting NCT03655912 - Binocular Visual Therapy and Video Games for Amblyopia Treatment. N/A
Recruiting NCT06150391 - Evaluation of Amblyopia Protocols Using a Dichoptic Gabor Videogame Program N/A
Completed NCT03754153 - Binocularly Balanced Viewing Study N/A
Terminated NCT02246556 - Dichoptic Virtual Reality Therapy for Amblyopia in Adults Phase 1
Withdrawn NCT02594358 - Caffeine in Amblyopia Study Phase 1/Phase 2