I have a natural over the counter supplement which is helpful for Alzheimer s patients which includes 15 mg of Uva Ursi. When I looked that up I found that it said Uva Ursi could thin the retina. I have not given it to my husband because he has at one time, many years ago, had bleeding on the retina and I am quite sensitive about his retina condition. I am curious to know if 15 mg is quite a low dose that would be safe. The other herbs etc. are: Vit C, B6, Niacin, Olive Leaf, Hibiscus, Hawthorne Berry, Buchu Leaves and Juniper Berry ... all of which seem helpful and not at all unsafe.