Hold the lens up to a bright light.

How to know if the contact lens is inside out. Inspect the contact lens from the side. For example, one brand has a 123 laser. The taco test is another way to tell whether your contact lens is inside out.

If the edges curve outward, then the contact is inside out. Simply place the lens between your thumb and forefinger. With the lens placed on your fingertip and the edges pointing upward, look at the shape of the lens from the side.

Usually, this will take the form of a sequence of numbers and/or letters. If it’s pointing upwards, or if the edges appear to meet, then the lens is the correct way around. Place the lens between your forefinger and thumb.

The edge of the lens faces inwards in a curve. Yes—and it matters more the higher your prescription is. If it looks like a mixing bowl (edges pointing straight up) you’re good to go.

The first is to examine the lens from the side. This is one of the quickest and easiest ways to ensure if your contact lens is inside out. Put the contact on your index finger with the edge pointed up and examine the lens from the side.

Leave enough space for the contact lens edges to move and gently squeeze the lens edges towards each other. There are two easy ways to tell if your contact lens is inside out, look at the shape of the contact lens, it should have smooth edges like a well turned bowl, or squeeze the lens. Place your lens on the tip of your finger.