Ask the Optician

Axis of cyl has changed and vision in one eye is not clear for reading


My prescription usually has a right eye axis in the range 110 to 125. For example, my last Specsavers (in 2007) was Left -8.50 +1.75 130 Right -7.75 +1.25 25.

I had a test with an independent optician giving: Right -6.50 -1.00 70. The glasses (progressives) felt strange. They were replaced. Still not right. So I had a retest by the same optician. The new prescription is: Right -6.25 -1.00 90. The new glasses are better but still not quite right. If I rotate the right lens a little (and close the left eye), near sight becomes much clearer, especially towards the edge.

Would my axis have changed that much? Do you think the optician has got the axis right?

Answer Written answer:

There are two ways of writing a prescription, one is called 'plus' cyl form and the other 'minus' cyl form. Both ways make exactly the same lens. To transpose a prescription from one form to another, add the sphere to the cyl, change the sign of the cyl, and change the axis by 90 degrees. Optical laboratories tend to work in 'plus' cyl form. Optometrist test in either form.

Having said that, there is still a small change in the axis which could cause problems if it is not right. The fact that when you rotate your varifocals you can read better in the right eye indicates that either the cyl axis is still wrong, or I think more likely, the reading area in the varifocals has been glazed slightly out, and needs reglazing with a new lens to the correct position.

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

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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.
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