Addition (ADD)

Addition, often abbreviated to ADD, is the extra positive power added to your distance prescription to enable you to see clearly at close range. You need this value when your eye’s lens becomes less flexible and can no longer focus properly at close range, a process known as age-related long-sightedness or presbyopia.

The addition value is stated on your prescription and is expressed in dioptres, usually between +0.75 and +3.00. The higher the number, the more extra power you need for close-up tasks such as reading, using a smartphone or doing handicrafts. The add is always a positive value and usually applies to both eyes, although there may sometimes be a slight difference.

You’ll find the addition in various types of spectacle lenses and contact lenses: reading glasses have only the addition value, bifocal lenses combine distance and reading powers in two zones, and multifocal or progressive lenses offer a gradual transition between all distances. In multifocal contact lenses, the addition is used to calculate the different zones within the lens.

When do you need an addition?

Most people find that, from the age of forty onwards, reading or other close-up work becomes more difficult. You hold a book further away, you need more light, or you get a headache when doing close-up work for long periods. That is when your optician or optometrist will prescribe an addition. The value usually increases as you get older, up until around the age of sixty.

Addition on your prescription

On your glasses or contact lens prescription, the addition is often listed as ADD, and sometimes as Near or NV (near vision). This value is added to your spherical power (SPH) for each eye. For example: if your right eye has a distance prescription of -2.00 and an addition of +2.00, your total reading prescription for that eye is 0.00 (plano).

Addition for contact lenses

Multifocal contact lenses use the add value to combine multiple powers in a single lens. The way this works varies depending on the lens design: some lenses have concentric rings, others use a gradual transition, or a division between the dominant eye for distance vision and the non-dominant eye for near vision. Your optician will determine which power and design suits you best. At SMEYEL , you’ll find multifocal contact lenses for various add values.

The difference between addition and reading power

Addition is the extra power you add to your distance prescription. Reading power is the total power you ultimately need to see clearly at close range. If you do not have a distance prescription (0.00), your reading power is equal to your addition. If you do have a distance prescription, you add the addition to it to get your reading prescription.