Avatar universal

Contact lens power for astigmatism

I am 24 years old.
I have been wearing glasses & contacts since 2002
Here is my latest prescription

SPH: -3.25
CYL: -0.5
Axis: 10

SPH: -2.5
CYL: -0.75
Axis: 160

Previously I had 0 astigmatism.

The optometrist prescribes me this for my contacts
Right: -3.50
Left: -2.75

She says that I have to compensate -0.25 each side for my astigmatism.
I am very confused because astig and myopia are two different things. How can one compensate for the other?
2 Responses
Sort by: Helpful Oldest Newest
Avatar universal
One way to think of the astigmatism (given the way your prescription is written) is that the myopia is worse in one direction than in the perpendicular direction.  (For example, it might be worse horizontally than vertically.)  So instead of perfectly spherical eyeglass lenses, you need lenses with a bit more correction at one angle than at the other.  

It wasn't until I hit my forties that I needed astigmatism correction, and was forced to switch brands of contacts to get toric lenses.  Although they were comfortable, they were never as comfortable as my previous, regular contacts.  I could only go eight or nine hours with them, while I was able to wear the others all day.  I don't know if that's true for all brands, but I would expect so, because they need a more complex shape and can't be as thin as regular contacts.

In your case, your eye doctor has given you a contact lens prescription that's (roughly) the average between the two directions, rather than making you wear torics.  Between the increased comfort of the regular contacts and the increased cost of the torics, I'd consider that a good trade, as long as the resulting vision meets your needs.

Helpful - 0
517208 tn?1211640866
Dear prolog,

You do not have much astigmatism and thus, will not need to correct it in contact lenses. To make sure that the image is projected clearly onto the retina a small adjustment to the spherical power of the lens is made for astigmatism.  This is known as the spherical equivalent of the prescription.

Dr. Feldman

Sandy T. Feldman, M.D., M.S.
ClearView Eye and Laser Medical Center
San Diego, California
Helpful - 0

You are reading content posted in the Eye Care Forum

Popular Resources
Find out how beta-blocker eye drops show promising results for acute migraine relief.
Eye whitening, iris color change, and eyeball "bling." Eye expert Dr. John Hagan warns of the dangers from these unnecessary surgeries.
Eye expert John Hagan, MD, FACS, FAAO discusses factors to consider and discuss with your eye care team before embarking on cataract surgery.
Is treating glaucoma with marijuana all hype, or can hemp actually help?
Protect against the leading cause of blindness in older adults
Got dry eyes? Eye drops aren't the only option! Ophthalmologist John C. Hagan III, MD explains other possible treatments.