Rod Sensitivity in Age-related Macular Degeneration (AMD) and Retinitis Pigmentosa (RP)

Study Overview
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Brief Summary
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A new fundus-guided microperimeter (MP-3S) has been developed by Nidek, Inc. to track the fundus of the patient and present stimuli in specific anatomically-defined locations. Furthermore, this tracking means that exactly the same locations can be tested on subsequent (follow-up) visits. The investigators will use a method called two-color perimetry to map rod and cone sensitivity on this device. With this technique, the sensitivity difference (blue-red) to chromatic test stimuli can be used to determine whether rods, cones or both photoreceptor systems mediate the threshold at a given location in the macula.

Detailed Description
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Despite recent advances in understanding the pathogenesis of retinitis pigmentosa (RP) and age-related macular degeneration (AMD), precise characterization of the disease phenotype remains elusive. In both diseases, much of the focus has necessarily been on the loss of cone function, since visual fields, acuity and contrast sensitivity are typically measured under photopic conditions. In RP, we need a greater understanding of patterns of rod loss since most disease-causing mutations affect primarily rods. In AMD, recent findings have shown that scotopic sensitivity can be much more affected than conventional photopic measurements such as visual acuity. For patients, however, it is difficult to maintain stable fixation, especially when central vision is compromised. A new fundus-guided microperimeter, the MP-3S, has been developed by Nidek, Inc. to circumvent this problem. The investigators will evaluate the value of this device for following rod and cone loss in patients with either RP or AMD.

Official Title
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Rod Sensitivity in Age-related Macular Degeneration (AMD) and Retinitis Pigmentosa (RP)

Conditions
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Retinitis Pigmentosa, AMD

Intervention / Treatment
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* Diagnostic Test: Rod sensitivity


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: clear media diagnosis of RP or non neovascular AMD normal volunteers Exclusion Criteria: exudative AMD other eye diseases that could cause vision loss physical ailments that would preclude comfortable testing unable to provide informed consent

Ages Eligible for Study
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Minimum Age: 10 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Retinitis Pigmentosa<br>patients with a diagnosis of retinitis pigmentosa and reduced rod function on baseline testing | Diagnostic Test: Rod sensitivity<br>* diagnostic test for rod loss in central retina<br>|
| Age-related Macular Degeneration<br>patients with a diagnosis of intermediate AMD and reduced rod function on baseline testing | Diagnostic Test: Rod sensitivity<br>* diagnostic test for rod loss in central retina<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Rod Sensitivity Within the Central Retina as Measured on the Nidek MP-3S | Number of participants with rod sensitivity measured in decibels at multiple retinal locations within the central retina | through study completion, an average of 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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microperimetry, rod visual fields