1 Visual acuity (sharpness) tests help your doctor find out if you have a problem that affects how well you can see. 2  They measure the eye's ability to see details at near and far distances. 3  The tests usually involve reading letters or looking at symbols of different sizes on an eye chart.
Amount of calcium. Elemental calcium is key because it's the actual amount of calcium in the supplement. It's what your body absorbs for bone growth and other health benefits. The Supplement Facts label on calcium supplements is helpful in determining how much calcium is in one serving.
Calcium supplements cause few, if any, side effects. But side effects can sometimes occur, including gas, constipation and bloating. In general, calcium carbonate is the most constipating. You may need to try a few different brands or types of calcium supplements to find one that you tolerate the best.