is this right? glasses RX -3.75 but contacts RX -4.25

[dbnyc]

i'm confused about why this is.
i had a bad experience w/ the staff of my doctor's office so i don't really feel comfortable calling to ask. the doctor seemed okay, but i'd rather avoid their office now.

anyway, my glasses RX for my right eye is:

-3.75 -1.00 x 5degrees

but for my contacts RX, my right eye is a power of -4.25. (i decided to go w/ a regular Acuvue2 lens, instead of a Toric lens)

this seems like a big jump from -3.75 to -4.25!

also, when i test my vision by covering my left eye and just seeing through my right eye, details are very blurry.

for example when i try to make out very tiny print letters from far away, i see double: i.e. an A would look like an M because it's looks like 2 A's overlapping.

if the -4.25 jump sounds correct based on my astigmatism, could someone please explain and help me understand?

TIA for your help.

[Diane]

dbnyc,

Based on your prescription, you will be compromising a bit of visual acuity (clear vision) by going with a spherical correction rather than being fit with a toric contact lens. You didn't mention your contact lens history....Were you previously wearing soft contact lenses??? The power your doctor's staff used could be classified as what we call a spherical equivalent, but that isn't necessarily the best choice. -1.00 of cylinder power should be corrected, unless you don't wish to achieve maximum visual acuity. Perhaps they already mentioned that to you, since you mentioned your choice of selection as being a regular (spherical power) lens, rather than a toric lens. What is your power in your left eye? Which eye is dominant, and even your age has a bearing on lens selection.... Gas permeable lenses could also be an options depending on where the toricity is located, and actually may maximize your vision over soft contact lenses or even spectacles.

Give us a little information, and we will all help you.

Diane

[Optom]

Hello dbnyc,
Yes this is OK.Actually it is not a big jump but R-4.25 is sphere equivalent(transformation) of your eye glass Rx -3.75/-1.00X005.
What is your left eye contact and spectacle rx?
Did you try talking your problem directly with your eye doctor.
Regards,
Optom

[Robert Martellaro]

If an astigmatic correcting lens (toric) is not used, the lens power is determined by adding half of the minus cylinder to the sphere, adjust for vertex compensation, then over refract for good measure.

Sphere equivalent -3.75 (+) -.50 = -4.25.

Vertex compensation- Doctors lens is typically 12mm (contact lens is on the eye at 0mm). Square the power (shortcut calc) 4.25 X 4.25=18.07. Multiply this result by the difference between the doctors vertex distance (12mm) and the wearers vertex distance (0mm) in meters which is .012 X 4.25 = .22. Add this result to the sphere equivalent and you get -4.03. One might start with a trial -4.00 lens then over refract for the final result. You were given a -4.25 which seems reasonable.

The double vision is probably due to the uncorrected astigmatism. If the vision with both eyes is unacceptable I would try a toric CL. Acuvue makes such a lens that might work for you.

Hope this helps

Robert

[dbnyc]

hi, my right eye is probably dominant? i'm not sure, but my left eye is a lot worse. so w/o wearing any glasses, i naturally see w/ mostly my right eye.

my left eye has no astigmatism and is a -6.50 power.
the contact lens RX for my left eye is also a -6.50 power.

i'm in my mid-20s. i've worn soft contacts for the past 10 years. B&L Optima until 2001 when my right eye and to a lesser extent my left eye started rejecting the contacts (irritation, pus, etc.)
since 2001, i wore glasses only.
until now got fitted for Acuvue2's which are much more comfortable (doctor speculated that i needed a higher water content lens). the Toric lens was not as comfortable, so i chose the AV2's, despite the blurriness in the astimatism eye. the vision in both eyes combined is good enough.

and i don't feel comfortable asking my doctor (someone random i found in the phone book and i didn't verify his accreditations) because the staff at his office are really shady and their biz practices are questionable.

[chip anderson]

Get fitted for rigid lenses or properly fitted for toric soft contact lenses and the double vision will go away.

Chip

Your actual Rx is -3.75 -1.00 x whatever. the actual power of such of a lens is -3.75 & -4.75 the average being -4.25. Your spherical (which appearently ain't makin it for you) soft contact lens power should be -4.25 or -4.00 depending on when your practioner thinks vertex (the distance from the examination lens to the eye ) becomes important.