Treatment of Bardet-Biedl-Syndrome With Metformin for Evaluation of a Possible Visual Improvement

Study Overview
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Brief Summary
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In this prospective pilot study without control group children and young adults (10-25 years old) diagnosed with Bardet-Biedl syndrome and treated with Metformin for their adipositas will be evaluated for a possible additional effect of Metformin on visual acuity.

Detailed Description
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Within experiments with animals a positive effect of Metformin concerning the photo receptors was shown. Several patients of the university hospital Tübingen with Bardet-Biedl-Syndrome and Metformin therapy due to their adipositas reported a subjective improvement of the visual acuity which was confirmed by opthalmologic tests. This will be checked in a prospective pilot study without control group including children and young adults (10-25 years old) diagnosed with Bardet-Biedl syndrome and treated with Metformin for their adipositas. Therefore a possible additional effect of Metformin on visual acuity will be evaluated under controlled conditions.

Official Title
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Treatment of Infantile and Juvenile Patients With Bardet-Biedl-Syndrome With Metformin. Evaluation of a Visual Improvement as a Side Effect of the Pediatric Treatment of Adipositas - a Prospective Pilot Study Without Control

Conditions
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Bardet-Biedl Syndrome, Visual Impairment

Intervention / Treatment
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* Drug: Metformin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: clinically confirmed Bardet-Biedl-syndrome Visual acuity between 0.05 and 0.8 Age >=10 year to <25 years Visual field III4e or V4e with diameter >=5°, if II4e not seen informed consent of patient and/or legal representative Exclusion Criteria: Hypoglycaemia (<50mg/dl) Therapy with Metformin within the last three months Participation in another clinical trial pregnancy, lactation any contra indication concerning Metformin therapy Renal failure (creatinine clearance < 60ml/min) any acute disorder accompanied by clouding of consciousness acute or chronic disorders possible accompanied by tissue hypoxia Liver insufficiency, alcohol abuse not fluent in German language

Ages Eligible for Study
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Minimum Age: 10 Years
Maximum Age: 25 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

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Interventional Model Description: Prospective pilot study without control group
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Metformin Therapy<br>Metformin therapy once daily for 24 weeks with a dose of 500, 850 or 1000 mg depending on body weight | Drug: Metformin<br>* 500, 850 or 1000 mg depending on body weight once daily for 24 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual acuity | Course of visual acuity according to appropriate table | Baseline to day 210 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of letters read | Course visual acuity defined as number of letters read | Baseline to day 210 | 
| Results of Static perimetry | Course of results of static perimetry given by measurement of light contrast sensitivity within at least 5 central points. | Baseline to day 210 | 
| Results of Kinetic perimetry | Course of results of kinetic perimetry given by mapping the visual field sensitivity boundaries using Goldmann perimetry | Baseline to day 210 | 
| Electroretinogram (ERG) dim-flash | Course of values of ERG dim-flash | Baseline to day 210 | 
| Electroretinogram (ERG) standard flash | Course of values of ERG standard flash at 3 ods/m2 | Baseline to day 210 | 
| Electroretinogram (ERG) cone-single-flash | Course of values of ERG cone-single-flash at 30cd/m2 | Baseline to day 210 | 
| Electroretinogram (ERG) 30-Hz-Flicker | Course of values of ERG measured by 30-Hz-Flicker in all patients | Baseline to day 210 | 
| Visual evoked potential (VEP) - amplitude | Course of results of measurement of VEP amplitude | Baseline to day 210 | 
| Visual evoked potential (VEP) - latency time | Course of results of measurement of VEP latency time | Baseline to day 210 | 
| FST | Full-Field-Stimulus Threshold | Baseline to day 210 | 
| optical coherence tomography (OCT) | Course of central thickness of retina measured by OCT | Baseline to day 210 |