Evoked Retinal Response

Study Overview
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Brief Summary
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Retinitis pigmentosa (RP) is the name given to a group of inherited eye diseases that affect the retina (the light-sensitive part of the eye). RP causes the breakdown of photoreceptor cells (cells in the retina that detect light). Photoreceptor cells capture and process light helping us to see. As these cells breakdown and die, people experience progressive vision loss. There is no known cure for retinitis pigmentosa. The investigators have observed that short pulses of focused ultrasound can cause perception of light when directed to spots on the retinal surface. The investigators propose to conduct a study to determine if pulsed ultrasound will stimulate the perception of light in the absence of functional photoreceptors in people with RP

Detailed Description
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Patients affected by retinitis pigmentosa (RP) and related diseases suffer loss of vision due to death of photoreceptor cells. The investigators have observed that short pulses of focused ultrasound can cause perception of light (phosphenes) when directed to spots on the retinal surface. If this phenomenon is caused by direct stimulation of the retinal nerves, which seems probable, then it might be possible to use this phenomenon to produce a form of vision in such patients. The investigators propose to conduct a study of a small cohort of patients affected by RP to determine if pulsed ultrasound will evoke a perception of light in the absence of functional photoreceptors.

Official Title
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Evoked Visual Response Using Pulsed Ultrasound

Conditions
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Retinitis Pigmentosa

Intervention / Treatment
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* Procedure: Ultrasound Stimulus


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: retinitis pigmentosa legally blind in at least one eye Exclusion Criteria: unable to lay down on an exam table

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Retinitis Pigmentosa<br>Subject will have retinitis pigmentosa and will be legally blind in one or both eyes | Procedure: Ultrasound Stimulus<br>* Short pulses of focused ultrasound will be directed at spots on the retinal surface.<br>* Other names: pulsed ultrasound;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Phosphene Perception in Response to Ultrasound Pulse. | The investigators will test the hypothesis that compression of retinal nerves by ultrasound force will cause perception of light (phosphenes) in blind subjects lacking functioning photoreceptors (retinitis pigmentosa). With each of two 5 msec ARFI exposures, if the subject either perceived the spark of light (phosphene), then it was documented as a positive response; if they did not, it was marked as a negative response. | Subjects will undergo a single examination of approximately 15 minute duration during which they will report perception of phosphenes during ultrasound exposure. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Vision loss, retinitis pigmentosa, acoustic radiation force ultrasound, RP, visual field loss, Photoreceptor, retina, progressive vision loss, ultrasound