unrealizable wishes of national authorities

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.

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.

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