People older than 40 usually need an extra pair of glasses for reading. With this calculator you can compute what kind of reading glasses you need.
If you are normally wearing contact lenses then you have two options when filling the form. You could for example simply enter 0 in field Power glasses for optimal far sight. Alternatively you could convert the power of your lenses into the power of equivalent glasses using this calculator. Enter then the computed power in field Power glasses for optimal far sight.
If the power of the pair of reading glasses is between 0 and plus 4 then a pair bought off the shelf should do. Otherwise you are better off using a tailor made pair from an optician.
Acknowledgement to dr. G.P. Heeg, Ophthalmologist, Groningen (The Netherlands) and Pauline from Raethuys Opticians, Amsterdam.