Re: Blurry Vision unavoidable with age and worsening near-sightedness? Also, Diameter changes between contact brands?
- From: "Mike Tyner" <mtyner@xxxxxxxxxxxxxx>
- Date: Mon, 14 Apr 2008 22:16:54 -0500
"Zarlot531" <xyzer@xxxxxxxxxxx> wrote
I am a 27-year-old male. A month ago, I was wearing Focus Dailies,
left eye -7.00 and right eye -6.00.
I'm an OD with 27 years of fitting Ciba contacts.
These felt okay on my eye, but I went to Lenscrafters recently because
my vision started getting kind of blurry, as usual after I've had a
prescription for over a year or so.
It reaches a point, often around age 27, when it surprises us and
_reverses._ It's best to test the lenses on your eye, not to assume that
more is always going to be better.
I decided to go with Optix 2 this time, mostly because she said the
Dailies only went up by - .5 once you got past -7.00. The doctor
gauged my prescription at -6.25 right eye, and -7.5 left eye. Here's
the deal: and this may show my ignorance, but my Diameter for the
Dailies is listed as 13.8. For the Optix, it's 14.2.
Forget diameter. It has little or no effect on the vision. It affects
comfort and fit, perhaps, but you'd hardly expect blurry vision from a
larger diameter, especially if the blur increases in daylight.
Even though the prescription is stronger, things are still blurry.
The blur may also occur because of an increase in astigmatism, or some other
corneal irregularity that isn't compensated by simply increasing spherical
power. Many people at your age wind up needing LESS, not MORE.
Honestly, I don't notice much of a difference between these and the
prior pair. I guess I didn't notice it at first during the week
trial, but I notice now and will probably go back to Dailies. It
doesn't feel like the contacts fit on my eye as well as the Dailies.
Do diameters generally vary between brands?
Diameters are generally chosen by the manufacturer to fit an optimum number
of different corneas. Most lenses these days are available in only one
diameter. Some are only available in a single diameter and a single base
curve. Until recently, all Acuvue Oasys were the same shape and size.
Also, I don't know if this was just last night, as I haven't been out
many nights, but my vision is actually CLEARER at night... especially
letters on signs and stuff. During the day, letters on signs are
blurry.
That's a curious observation but it only points out the need for a different
approach to solving your problem.
For the sharpest vision, you need to ask your doctor for a sphere and
cylinder over-refraction, measuring the total prescription lacking with each
version of contact lens. Thickness and stiffness vary the response of one
contact from another, for these subtle aspects. The O2O is stiffer, IIRC,
but it may also be thinner than the FD.
Point is, only an overrefraction will explain which lens does a better job
at approximating your total prescription. In your range, there is a large
and often individualized difference between eyeglass and contact lens
prescriptions, and one should be used only as a general predictor of the
other.
-MT, OD
.
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