Re: Optical zones for contacts

mike

that information is available in a publication called Tyler's
Quarterly. It is also available in a website at
http://www.eyedock.com/index.htm (search under contact lenses under
advanced search).

the idea of the cause of the halos you see is plausable but no the only
explanation. for example, perhaps you have some uncorrected
astigmatism with your contacts on. also, perhaps you might benefit
from a lens with an aspheric design. go to your contact lens fitter
and ask for their opinion on lenses you might try. you are more likely
to find success since your fitter knows as much about contacts as you
do about astronomy/telescopes. we deal with these halo complaints all
the time.

---------------------

Mike Ruskai wrote:
> I started wearing contacts just over a week ago, and now have one
> sample pair each of Acuvue 2 (AV2) and Focus Night & Day (FND). I
> will likely get a sample of Acuvue Oasys when I go back sometime this
> week (I work on a computer, and the CRT monitor has a fair amount of
> drying power).
>
> I'm interested in doing extended wear for a few days at a time, as the
> mood suits, which is why I'm trying the FND, but there's something
> more important to me - night vision.
>
> I'm an amateur astronomer, so night performance is pretty important.
> More than that, since not having to deal with the hassle of glasses
> when using binoculars or a telescope is one of my main motivations for
> getting contacts (the others are comfort, vision correction, and all
> the annoying ways in which stuff gets on glasses - rain, sweat, etc.).
>
> I noticed last night that the FND lenses did not produce sharp images
> of stars, or any light source in the dark. After doing some blinking
> and nudging to see if I could get a better image out of them, I
> removed them and put the AV2 lenses in. While I still get halos
> around light sources in the dark, star images look sharp - much
> sharper than they ever did with any pair of glasses (managed to spot
> Pleione, Celaeno, and Asterope in the Pleides, with a 3/4 moon under
> normally mag 6.0 skies, if any of you know understand the significance
> of that).
>
> Since then, I've been trying to find information on the size of the
> optical zone of these lenses (and AVO, since I'll be trying them as
> well). I figure they must be too small to correct all rays entering a
> dark-dilated pupil.
>
> But I can't find that information anywhere.
>
> Does anyone know where I might find a list of various lenses with
> their optical zone sizes?
>
> Beyond that, I notice that the Acuvue Oasys lenses have an oxygen
> permiability not much less than Focus Night & Day, and are also made
> of a silicone hydrogel. Am I correct in guessing that they'd be just
> as good as FND for several-day extended wear, with proper rest and
> lens cleaning between wearing sessions?
> --
> - Mike
>
> Ignore the Python in me to send e-mail.

Hi Mike ,

for some time I had already planned on posting my experiences with the
optical zones of various lenses to this newsgroup.
Unlike retinula wrote, not all contact lens fitters (regardless of being
ophthalmologists or optometrists) have experience regarding this. I've
had both an optometrist as well as an ophthalmologist tell me that there
is nothing that can be done about the problems I had (seeing halos).
Both had sold yearly lenses (Lunelle) to me that have a very small
optical zone. They also insisted that these would be the best lenses for
long wear times (which obviously is not the case anymore, with all the
silicone-hydrogel options - at least if astigmatism correction isn't
needed).
Only by doing my own research I found out what the problem was (by the
way, thanks a lot to all the professionals sharing their knowledge here
and in other places on the net!).

So far I have tested theses lenses: Acuvue Oasys, Acuvue Advance,
Coopervision Proclear Monthly, Bausch & Lomb Purevision, Cibavision
Airoptix and Cibavision Focus Night & Day.

Focus Night & Day seems to have by far the smallest optical zone, though
as you pointed out there is no information available on the internet as
to how big it is exactly.

Bausch & Lomb Purevision have 8.9mm according to eyedock which should be
correct. I still have problems in very lowlight situations

Coopervision Proclear have 9mm according to Coopervision Germany and
contaguide (a highly recommended site, however it is in French. It has
some of the infos that eyedock doesn't have:
http://www.contaguide.com/pro/lentilles.php ). Still getting slight
problems with the optic zone there.

I think that Cibavision Airoptix have a bigger optic zone than Focus
Night & Day though probably smaller than 9mm (note these are subjective
opinions, I haven't got any factual data to back that up with, yet). At
least I still get problems here too.

Acuvue Oasys is fortunately among the lenses that work best for me in
terms of optic zone (unfortunately no data about it available online),
I've been using it a lot, with the occasional extended wear too. In
general it is by far one of the most comfortable silicone-hydrogel lens
(Purevision, Airoptix and Focus Night & Day all have quite a high
modulus which becomes evident already when handling the lenses). However
slight problems with halos remain for me (in very low light
situations). At least going to the cinema is possible for me with
them (though in some lowlight movie scenes I do get halos).
For me Oasys do outperform all other non-Acuvue silicone-hydrogel lenses
in terms of both comfort and optic zone.

Finally Acuvue Advance is one lens where I don't see any halos at all,
so in terms of vision they are a dream. However I can't keep them in as
long as the Oasys ones, especially if I don't have rewetting drops
available. But I still have to test some more to know for sure, but have
to get a new pair as my current obviously didn't like being stored in 3%
peroxide for a longer time.

So for now I guess I'm sticking to Acuvue Oasys myself (and maybe
occasionally Advance) and I would highly encourage you to try them,
nightvision should be a lot better and you will probably like the added
comfort, too.
I'm planning on asking at the various companies for the exact sizes of
the optic zones (however I don't know how much these are also dependent
on the indvidual lens power) and will post again to this newsgroup when
I know more. Also I think it is a good idea to give the companies
feedback - I don't know how many people have these problems (and to what
extent). Soon there should also be the new Coopervision Biofinity Lens
which I'm looking forward to very much. However my hopes for a bigger
optic zone aren't that big.

A big enough optic zone combined with a comfortable silicone-hydrogel
lens would be a dream come true for me (especially as I get some slight
haloing in very lowlight situations with glasses, too. I assume that
this might have to do with corneal abberations present in the outer
regions of the cornea. With Advance I have almost perfect vision).


That's it from me for now. Hopefully this info is useful to someone
else, too.

Andi