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.
The body's ability to produce vitamin D from exposure to sunlight and to absorb calcium and vitamin D decreases with age. Getting enough vitamin D helps the body absorb calcium and also helps the kidneys break down and incorporate (resorb) calcium that would otherwise be excreted.