Soft contact lenses can be turned inside out. It then becomes difficult to know which is the right way around. This is especially a problem when I have put contact lenses in, then accidentally knocked one of them out due to forgetting I had them in and rubbing my eyes, for instance. At this point the contact lens may have twisted due to the fact that I rubbed my eyes. How can I tell which way is the right way around before I put the lens back in?
There are a few ways to check that, allaboutvision.com has some great information on various ways to check the orientation of a contact lens:
Method 1: The Side View
If your contact forms a perfect cup-shape with the edge perfectly upright, the lens is correctly oriented and is ready to be placed on your eye. If the edge has a noticeable outward bend (like a rimmed soup bowl), the contact is inside out.
Method 2: The "Taco Test"
Place the contact lens between the tips of your thumb and forefinger, grasping it near the center so the entire edge is free. Gently squeeze the lens, as if you are about to fold it in half.
If the edge of the lens points upward (resembling a hard-shell taco), the lens is correctly oriented. If the edge bends outward (toward your thumb and finger), the lens is inside out.
Method 3: Check The Edge Tint
If the color of the handling tint on the lens edge looks very blue (or green, depending on the tint), the lens is correctly oriented. If the color looks pale or washed out, the lens probably is inside out.
Method 4: Look For Laser Markings
Some contact lenses have a laser marking to help you determine if your contact is inside out. For example, one brand has a "123" laser marking near the edge of the lens.
If the "123" appears normally, the lens is correctly oriented and ready to be placed on your eye. If the "123" is backward, the contact is inside out. If at first you don't see the laser marking, turn the lens on your fingertip to make sure you check its entire surface.