I have noticed that you can buy cat eye contact lenses. These are non-functioning contact lenses which change the appearance of your eyes to look like those of a domestic cat. This means the pupil is a slit rather than circular. And the iris is brightly coloured in these contact lenses as you can see in this yellow one in the photograph. They are obviously a bit of fun to be used at a celebration or party or whatever. Do they affect eyesight in terms of colour? Their appearance looks as if there might be some change in colour balance of the image recorded by the eye.
Note: not all cats have slit eyes. For instance, the tiger has a circular pupil. You can buy tiger eye contacts. Although I can’t see the point as humans have circular pupils too.
I think that you have got to be cautious when you use these. The Healthline website says that you should only purchase them from a reputable supplier who requires a prescription. They describe these contact lenses as a ‘medical device’ which should be regulated by the FDA. If they are sold without a prescription in the US, it is illegal.
You can buy them online without a prescription in the UK for about £15. Delivery is 2-3 business days. Certainly, in the UK there appears to be no need for a prescription and they are sent to you by courier or in the post in the usual way. I still think that you have to be careful because you are, after all, attaching something to the cornea of your eye. If that product is of insufficient quality, it may damage the cornea of your eye and affect your eyesight for the rest of your life.
I am painting a black and perhaps impossibly negative picture but there are some dangers as I see it. It depends how concerned you are about appearance at say a Halloween party compared to the potential for damage to the cornea of your eye. I think it might be wise to check with your physician before trying them out.
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