Ask the Optician

Specifying prism in glasses


If a patient needs a 3 prism base in for convergence, could the prism have been specified using any other system acceptable to British Standards other than giving 1.5 base in on right eye and left eye?

Answer Written answer:

I am not entirely sure what you mean, but if someone needs a total amount of 3 prism dioptres base in, this can be put in one eye only, or split between the two eyes, not necessary equal in both. For example, there could be 2 prism dioptres in one eye and 1 in the other. How this is prescribed however, depends on clinical tests, and it is up to the optometrist to specify the prism required in either eye.

We recommend you seek professional advice if you are concerned about your eye health:

Book an appointment

Optician's Biography

Simon Kay BSc(Hons) MCOptom has been a qualified Optometrist for over 35 years, and has a vast experience of almost all aspects of optometry. He joined Specsavers Opticians in 1993 first in Liverpool and for 15 years as a director of Lancaster and Morecambe. He served on many panels and committees whilst a director, including those responsible for IT design and professional advancement. He was regional chairman of the North West directors of Specsavers for over 12 years and as such was involved in almost all aspects of optometry on a business and professional level. He has been involved on the Local Optical Committee for many years and is currently Vice Chairman in his area.
Share this
  • Twitter
  • Facebook
  • email
  • StumbleUpon
  • Delicious
  • Google Reader
  • LinkedIn
  • Tumblr
    Ask the optician, receive friendly, professional advice