How can I tell if my contact lens is inside out?

Before you take a look at your lens, make sure it’s free from any excess solution or cleaning fluid that might make holding it much more difficult. You need to be able to position the lens properly on your finger before it can be placed into your eye.

One of the quickest and easiest ways to check if your contact lens is inside out, is to turn and examine it closely from the side. Place the lens on the tip of your finger with the edge facing upwards and hold it close to your eyes so that you can get a better view. If the lens is correctly positioned then it will be cup-shaped with the edges curved upright, whereas a v-shape with a clear rim around the edge will indicate the lens is turned inside out.

Another simple and effective way of checking the position of your contact lens is to carry out the half-moon test. Hold the lens in the centre firmly between your thumb and index finger, ensuring that you have a clear view of the outside of the lens. Squeeze it gently as if you are attempting to fold it in half.

With the edge facing upwards, the lens should be in the shape of a half-moon and you can safely insert it into your eye. If the rim is facing outwards in the direction of your thumb and index finger, the lens is inside out and you should reverse it, placing it in the palm of your hand to do so, if it helps.

Some contact lenses have a handling or visibility tint, usually green or blue, around the edge of the rim. While the tint doesn't cause any problems in terms of obstructing your vision, it makes holding the lens much easier and can help you to insert it more precisely.

To use the tint to determine whether the lens is turned the correct way, place it on the tip of your finger and examine the colour on the rim. A bold green or blue indicates that the lens is correctly positioned whereas a faded or lighter tint suggests that the lens needs to be reversed.

Some contact lenses have laser markings which are present to help you to tell whether they are turned correctly. These markings may be numbers, such as '123', which, when viewed from the side, should read normally from left to right. Numbers which are reversed or upside down will indicate that the lens is turned inside out.

It is worth noting that the laser markings may only be visible from one side of the lens so, if they are not immediately apparent, turn the lens slowly until you find them.

With time and practice putting in your lenses will become second nature, and you’ll rarely spend much time examining them before you know if they are inside out or not.

In the event that you insert your lenses the wrong way round, you can be reassured that your eyes will not be damaged even if the sensation is uncomfortable. As soon as you sense that the lens is inside out, you should remove it with clean hands, clean the lens with an appropriate solution and reinsert it, having checked that it is the correct way round.

Remember, dirt that gets between the contact and lens and the cornea, the surface of your eye, will cause irritation and discomfort and could cause damage to the lens. For this reason you should always ensure that you observe strict hygiene and cleaning when preparing your lenses:

• When inserting a lens, try to avoid using your fingernails, especially if they are long or sharp. Soft permeable contact lenses are fragile and can be easily damaged, rendering them useless.

• Use an appropriate cleaning solution to ensure your lenses are free from dust and dirt.

• Always store your lenses in their container to ensure that they remain in optimum condition.