Do bifocal soft contacts work well
Prof. Beaker
that age of needing reading glasses.
Are there disposable soft contacts that can correct for near
and far sightedness?
drfr...@my-deja.com
that work pretty well in many cases. Early presbyopes
with a straight-forward distance refractive error (ie.
w/o too much astigmatism) seem to do best with these lenses.
frank
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Dennis Roark
implants are supposed to work. In a regular bifocal or
progressive the eye moves down but the glass stay fixed.
This permits the eye to see through a different lens
prescription, designed for close up work.
In a contact or implant, any attempt to move the eye to look
down at close material will move the contact / implant as
well, with vision still going through the center part of the
lens.
It seems Hocus Pocus nonsense to expect contacts or implants
to get around this. Just take a moment and think how the
eye looks through a different region of the lens (lower
region which has an add) for standard eye glasses in a
frame. Then tell me how it might work with contacts /
implants.
Perhaps this analysis explains why those who have tried
bifocal or progressive implanted lenses after cataract
surgery report poor results.
drfr...@my-deja.com wrote:
---------------------------------
Dennis Roark
Dept. of Computer Science
University of Sioux Falls
Starting Points: http://home.earthlink.net/~denro
---------------------------------
Dick Claiborne
> I would find interesting how contact bifocals or bifocal
> implants are supposed to work. In a regular bifocal or
> progressive the eye moves down but the glass stay fixed.
> This permits the eye to see through a different lens
> prescription, designed for close up work.
>
lens wearers without taking off my shoes. I know I'll be disputed by some
of the O.D.'s in this group, but my opinion is very low of multifocal
contacts. My own experience with these lenses is that you have diminished
vision at all ranges, and most of the lenses gave me ghost images up close
and on my computer (and since I do refractions and fit contact lenses, I
have tried about 10 different types of bifocal contacts, excluding RGP
lenses). Don't get me wrong, if someone is lovin' them, then that's great.
But, because of my own experience, and the lack of patients I have seen I
will continue to be dubious about the value of these lenses. Of course, I
didn't purchase any of the newer soft fitting sets, so I'm not desperate to
break even on these.
Larry Bickford
Claiborne" <refr...@home.com> wrote:
> > I would find interesting how contact bifocals or bifocal
> > implants are supposed to work. In a regular bifocal or
> > progressive the eye moves down but the glass stay fixed.
> > This permits the eye to see through a different lens
> > prescription, designed for close up work.
> >
> In 29 years of refracting, I can count successful and happy bifocal
> contact
> lens wearers without taking off my shoes. I know I'll be disputed by
> some
> of the O.D.'s in this group, but my opinion is very low of multifocal
> contacts.
OK---here you go: (Reply to Dick, first, then Dennis)
I have DOZENs of perfectly happy bifocal/multifocal contact lens wearers
in my practice, including myself and my office manager. Including soft
multiaspheric, RGP multiaspheric and RGP segmented bifocals. Some of
these folks have *excellent* vision at all distances and others do have
some optical compromise at some distances.
I have a 90% success rate in fitting these things and a very, very low
drop-out rate. Understand that these stats are achieved by careful
selection of the patients to trial fit and careful selection of a lens
that best suits their needs. But even "random" fitters can get 70%
success. Inexperienced and careless lens fitters is what gives folks
the impression that "these things dont work".
With regard to the previous posters question on IOLs:
Implanted IOL multifocals achieve their optics by one of two methods:
the first IOL used diffraction grating to create a holographic-like
simultaneous vision (both distance and near focus viewed
silmutaneously). The brain would learn to process the two images as
needed. The problem with this design is that both images contain one
half the brightness and there is contrast loss.
The next design uses multiple aspheric curves like the soft contact lens
multifocals. This produces another type of simultanous vision images but
with signficantly greater brightness but also with some loss of
contract sensitivity. Use of this lens has proven to be successful in
many cases but surgeons have problem using it because "unhappy" patients
require explant (removal) and re-implant of another IOL. Additional
surgery also brings additional surgical risk. It is, however, becoming
increasing popular, epsecially outside the USA.
A third design used a hinged haptics model, which allows the lens to
move anterior/posterior as the ciliary muscle induces accomodation (as
the normal lens works). This is gaining in acceptance, although a very
new concept and still considered "experimental". The advantage is much
better optics at all distances. The disadvantage is that it may stop
working---and each lens not necessarily at the same focus point,
requiring spectacle/contact lens correction to compensate.
I'd suspect that some sort of combination of these designs will soon
become a common lens replacement modality.
---LB
--
Larry Bickford, OD
Doctor of Optometry, Family Practice Eye Health and Vision Care
The EyeCare Connection
http://www.EyeCareContacts.com
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Beatrice C.
and -6.5(right). I have better distance vision now than I have ever had with
glasses. And my computer screen is clear. That's the good news. The bad news
is that I still need magnifiers to read or knit. But I am willing to put up
with that.
Beatrice
"Larry Bickford" <larr...@eyecarecontacts.com.invalid> wrote in message
news:larrydoc-CE2EB6...@news.west.net...
Dick Claiborne
I know I'll be disputed by
> > some
> > of the O.D.'s in this group, but my opinion is very low of multifocal
> > contacts.
>
> OK---here you go: (Reply to Dick, first, then Dennis)
>
> I have DOZENs of perfectly happy bifocal/multifocal contact lens wearers
> in my practice, including myself and my office manager. Including soft
> multiaspheric, RGP multiaspheric and RGP segmented bifocals. Some of
> these folks have *excellent* vision at all distances and others do have
> some optical compromise at some distances.
>
> I have a 90% success rate in fitting these things and a very, very low
> drop-out rate. Understand that these stats are achieved by careful
> selection of the patients to trial fit and careful selection of a lens
> that best suits their needs. But even "random" fitters can get 70%
> success. Inexperienced and careless lens fitters is what gives folks
> the impression that "these things dont work".
>
lenses, and I'm happy for your success. I'm sorry that you feel that I'm
inexperienced or careless. If so, I guess I'm only careful with the
hundreds of keratoconus lenses I've fit, or the thousands of lenses that
have been successful fits. I won't dispute your 90%, because I don't want
this thread to go nuts; I simply cannot disprove you, and certainly you
can't show me any published statistic showing even a 70% success rate with
multifocal fits (and if you did then we'd have to argue on the validity of
the source). I only wish I could refer you all of the patients we see from
these "inexperienced and careless fitters" who lament about the fitting
costs wasted and don't want to return to the doctor only to be charged more.
Or, maybe we're just not "selective" enough.
drfr...@my-deja.com
regarding expectations are key. I do very well fitting the
multifocal designs, both the rgps and the soft. These are
not for everyone but in the provider who knows how to fit
these designs the success is quite high.
Michael Pace
including every patient who comes in asking for soft bifocal contacts is
about 25% to 30%, but the success rate with those that I actually spend a
fitting appointment with is closer to 70% to 80%. The key to successful
bifocal fitting is patient selection. If you read between the lines of
published studies and question fitters closely you will find that a large
number of potential wearers are "disqualified" for various reasons before
fitting begins. Of course, you and I have to deal with walks through the
door, not a nicely preselected group.
Closely question your prospects; if they have precise visual demands forget
it and never fit an engineer ; ). Introduce a plus ret bar over patient
wearing distance correction, slowly increasing the plus over one eye with
both eyes open until blur is noted. If they can only tolerate less than
1.00D, forget it.
I send them out for a few days with a pair of J&J or Ciba trials, selected
with the manufacturer's nomagram (minimizing my time) and have my staff
follow up with a phone call. If they hate it and really notice the ghost
images etc, etc, we call it quits. If they can tolerate it, then I bring
them in for a proper fitting, over refraction and fine tuning of the powers.
The rigids are a different story; the segmented types are great, the
multiaspheric and simultaneous vision types are like the softs.
I think the real problem is not with the lenses, but with the patient's
perceptual system. Many people cannot tolerate the simultaneous vision
found in all soft designs; they will do better with monovision, RGP
segmented bifocals or the best solution of all: distance contacts with half
eye readers.
MP
Dick Claiborne <refr...@home.com> wrote in message
news:k4U36.67593$A06.2...@news1.frmt1.sfba.home.com...
>
> I know I'll be disputed by
> > > some
> > > of the O.D.'s in this group, but my opinion is very low of multifocal
> > > contacts.
> >
snip