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Medical Forum / General / Vision / February 2006

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Ortho-k night vision

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Scot - 04 Feb 2006 13:00 GMT
If you read my other post you will have a basic idea of my situation,
but quickly stated:
I have been wearing ortho-k lenses for a few weeks and have excellent
daytime vision, but dim/night conditions are what I would consider to
be very poor.  I see halos around light on dark objects (white on black
writing, white window trim on a brown wall etc) and I see starbursts
around distant lights.   While driving I have an odd combination of
very sharp vision and starbursts that make me feel like I cannot focus.
If I am in "city" conditions with lots of traffic and light around me,
the issue is minimal, but on a fairly empty highway it is very
noticable.  - It is not my vision fading, if I go into a very bright
room I can see perfectly, even late, my vision only fades to about
20/20 by 11pm (20/15 in the mornings).

So far my doctor has used flourescine die with a light slit/keratometer
and a large square "magnifier" type tool to determine centration, but
not a topographer. I asked about a topography but he stated it would
not provide any additional information at this point. He stated that
the flourescine would show centration, even from sleeping.

At my last appointment he did not have anything new to offer, but
suggested I continue using the lenses for another week or two and come
back.  If I am still having issues, then we wil see what we can do.
Unfortunately I have seen no reduction since Tuesday, and am having my
doubts that I will see any additional reduction, so I am looking for
some recommendations here.

One thing I noticed this morning.  Upon waking up I looked at the trim
in the room, as it is white on brown and can produce a pronounced halo
in dim light for me.  Definite halo around all of the trim with the
lenses in.  I proceeded to put a few drops of rewetting solution in my
eyes and napped for about 5 more minutes.  This time when I opened my
eyes up again my lenses were moving freely, where they were not before,
and looked at the trim again.  This time rather than seeing the halo
stay solid, I saw that every time I blinked the halo would come back,
then it would slowly dissapear as the lens moved.  I know for a fact
this was happening as the lens moved because of the visable bottom lens
edge, I cannot look at it directly of course, but I can clearly see it
and watch it move without a mirror.

I don't want to self-diagnose, but does this sound like it is a
centration issue or just an aspect of wearing OK lenses?  Could my
eyelids be moving the lenses off center enough to cause vision issues
during the day? Would my doctor not be able to tell about my night
centration issues using flourescine?

Thanks!

(before the crew goes at it, no the lenses don't hurt, yes my vision is
great in the mornings, no it doesn't fade quickly, no driving isn't
dangerous, no I havent changed my license just yet, no it isn't
annoying to do, yes i can sleep just fine, and no I don't want your
opinions of lasik vs AOK or mumbo jumbo about positive lenses or
whatever.  please don't post in this thread if you are not actually
responding to me about my questions, use my other ortho-k thread for
that)
Dr. Leukoma - 04 Feb 2006 13:55 GMT
I'll be happy to take the first pass at this, Scot.  One of my
specialties is the complicated post-refractive surgery patient, where
decentered ablations or large pupils relative to the diameter of the
ablation are prevalent.  Therefore, I can say with almost complete
confidence that you are having an optical zone issue, and most likely a
decentered optical zone.  The proper way to diagnose this is with
corneal topography.

The treatment will involve either making the optical zone larger,
improving the lens centration, or both.  By the way, my chief criticism
of OK has been that while the LASIK industry is beginning to catch up
with the ablation diameter issue, OK seems to be stuck with a 6.0 mm
optical zone.  Also, the centration issue can be difficult to solve
with some patients.

DrG
http://www.coppellfamilyeyecare.com
dragonlet - 07 Feb 2006 16:47 GMT
In dark situations, your pupil enlarges to allow more light in.

The edge of your treatment zone in ortho-k must be on the border o
your pupil, be it because it is off center or the treatment zone i
too small.  That is why the halos occur

I have read that you said your doctor said the lens is centered an
the treatment zone is centered.  Although his method of determinin
this seems to differ in the way our practice does it (I'm not sayin
it is not accurate..)

The only thing I can think of: the optical zone treatment is too smal
compared to the size of your pupil in low light conditions
Scot - 10 Feb 2006 20:03 GMT
How do you determine centration and do you think there is a problem
with using a keratometer with light slit to see how it is working?

One thing that I find interesting is that the halos are not even, and
they also appear in what might be considered normal light conditions.
Say in an office building on an overcast day.  the halos around solid
objects normally appear as if an object is slightly glowing "down and
to the right" in my right eye, and "downwards" in my left, and not an
even glow all the way around.

My next appt is next weekend.
Dr. Leukoma - 11 Feb 2006 03:37 GMT
Of interest is whether the treatment zone is symmetrical and regular.
In my opinion, this can only be determined with topography and not by
visual observation.

DrG
http://www.coppellfamilyeyecare.com
Scot - 11 Feb 2006 15:18 GMT
That makes sense.  I will request, again, to have a topography run.

If he does not believe in it/won't run a topography and cannot provide
me any further possibilities for a solution, do you think I could get a
second opinion from another doctor without starting a full AOK program?
Basically just have another doctor run a topography and see if it has
any overt details on whats going on, or does it take more than just
sitting infront of the machine and having the doctor review the output?
(ie multiple visits, a full exam and test of my eyes etc)  I would only
be seeing a doctor that is familiar with AOK of course.  I am
definitely willing to pay of course! :)

I really think this information is valuable to me and could definitely
be useful for other Ortho-K prospective/current patients.  So again,
thank you for the help.

Scot
Dr. Leukoma - 11 Feb 2006 16:16 GMT
Scot, based upon the symptoms, we can be certain that either the
treatment zone is decentered, or is too small relative to the dilated
pupil, or both.  The question is, what diagnostic test would be
appropriate?  The anwer is: topography.  Any doctor who uses topography
better be able to interpret the image, just as a radiologist can
interpret a CT.  If you value a continued relationship with your
current doctor, then be persistent in your complaints.  If he
repeatedly dodges the issue, can or won't offer any solution, then you
might want to pursue a second opinion.  He may very well say that you
have come up against the limitations of what can be reasonably
accomplished with OK without getting experimental.  Or, he may say that
he can solve the problem, but it will cost additional $$$.

DrG
Scot - 21 Feb 2006 15:20 GMT
Verified that the lens is decentering.  Not a 100% shot at fixing it,
but at least we are getting somewhere.  By manually centering the lens
with tension on my eyelid I can drastically reduce the halo or change
its direction if the lens moves too far.  When "centered" the halo is
reduced dramatically, but won't stay as blinking reverts the lens to
the off center position.

Right lens is riding high and to the inside and the left is riding
straight up.  This results in a nice halo that points the opposite
direction of the off center part of the lens both eyes, with the lenses
in or out. Seems to be caused by my astigmatism forcing the lenses to
ride off center, even though my astigmatism is described as "minor" and
was never enough to require torics or other correction with soft
contacts.

To combat this I now have been prescribed slightly larger lenses.  They
still seem to ride high when my eyes are open and they are in, but the
larger lens is supposed to ride lower when my eyes are closed,
hopefully suppressing the influence of my astigmatism.

Scot
CatmanX - 21 Feb 2006 22:14 GMT
The lenses are probably flat, that causes them to ride high. The lens
needs to be steepened by 5-10 microns or increase by 1 return curve if
using CRT (25 microns).

dr grant
 
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