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Safe use of cheap distilled water to clean contact lens

 
 
George Bray
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      08-04-2004, 08:22 AM
I am thinking of using the de-ionised water sold for topping up car
batteries.

Now I know the battery water may be crawling with bugs, so I intend
taking some precautions. Will my precautions be sufficient, or am I
still running a big risk?

1: Boil the battery water for ten minutes in a covered saucepan on the
stove. This should kill most bugs.

2: Add a pinch of (non-sterile) table salt, for what it's worth, to
resemble saline solution. Also add a couple of drops of hydrogen
peroxide solution, since I noticed there's a bit of that in commercial
saline solution. It might help keep the bugs at bay.

3: Dissolve a protein tablet in my DIY saline solution and leave the
lens soaking overnight.

4: Rinse lens with more DIY saline solution.

5. Place in hyrdogen peroxide (stage 1) cleaner and leave for at least
an hour.

6. Neutralise (stage 2) and wear.

Logic: the boiling and hydrogen peroxide process will kill all bugs.
DIY saline is cheaper than using commercial solutions, other than for
final disinfection by hyrogen peroxide or heat treatment.

I read that pure distilled water can expand the thickness of soft
contact lenses, and damage them, but I simply cannot believe it. How
can distilled water with a pinch of salt be significantly different to
commercial, sterile saline solition?

Regards
George
 
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Robert Redelmeier
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      08-04-2004, 04:11 PM
George Bray <(E-Mail Removed)> wrote:
> Logic: the boiling and hydrogen peroxide process will kill
> all bugs.


Yes, but only when boiled. The bugs will grow in whatever
bottle you put your "saline". Acanthamoeba spores are
very resistant.

> DIY saline is cheaper than using commercial solutions,


Somewhat. The problem is keeping it sterile.

> I read that pure distilled water can expand the thickness
> of soft contact lenses, and damage them, but I simply
> cannot believe it.


Believe! Or read up on the chemistry of polymer hydrogels.

> How can distilled water with a pinch of salt be significantly
> different to commercial, sterile saline solition?


Osmotic pressure if you con't match concentrations. Put an
old lens in very salty water and watch it shrivel.

-- Robert

 
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The Real Bev
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      08-06-2004, 01:10 AM
Mike Tyner wrote:
>
> "George Bray" <(E-Mail Removed)> wrote
>
> > I read that pure distilled water can expand the thickness of soft
> > contact lenses, and damage them, but I simply cannot believe it.

>
> No question it expands them. Damage? Probably worse for some materials than
> others. I'd guess the lower-water materials like polymacon handle it better.
>
> > How
> > can distilled water with a pinch of salt be significantly different to
> > commercial, sterile saline solition?

>
> Acanthamoeba is harder to cultivate from commercial saline.


Commercial saline is dirt cheap. While I'm as eager as the next person
to save a buck, in this case it seems like more trouble than it's
worth.

--
Cheers,
Bev
================================================== ================
"America is at an awkward stage: it is too late to work within the
system, but it is too early to shoot the bastards." -Claire Wolfe
 
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Dr. Leukoma
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      08-06-2004, 12:24 PM
(E-Mail Removed) (George Bray) wrote in
news:(E-Mail Removed) m:

> I am thinking of using the de-ionised water sold for topping up car
> batteries.
>
> Now I know the battery water may be crawling with bugs, so I intend
> taking some precautions. Will my precautions be sufficient, or am I
> still running a big risk?
>
> 1: Boil the battery water for ten minutes in a covered saucepan on the
> stove. This should kill most bugs.
>
> 2: Add a pinch of (non-sterile) table salt, for what it's worth, to
> resemble saline solution. Also add a couple of drops of hydrogen
> peroxide solution, since I noticed there's a bit of that in commercial
> saline solution. It might help keep the bugs at bay.
>
> 3: Dissolve a protein tablet in my DIY saline solution and leave the
> lens soaking overnight.
>
> 4: Rinse lens with more DIY saline solution.
>
> 5. Place in hyrdogen peroxide (stage 1) cleaner and leave for at least
> an hour.
>
> 6. Neutralise (stage 2) and wear.
>
> Logic: the boiling and hydrogen peroxide process will kill all bugs.
> DIY saline is cheaper than using commercial solutions, other than for
> final disinfection by hyrogen peroxide or heat treatment.
>
> I read that pure distilled water can expand the thickness of soft
> contact lenses, and damage them, but I simply cannot believe it. How
> can distilled water with a pinch of salt be significantly different to
> commercial, sterile saline solition?
>
> Regards
> George


Acanthamoeba is a ubiquitous (i.e. found in many places) unicellular
organism. It exists in trophic and cystic forms. The cysts are difficult
to kill and can remain dormant for a long, long time. It takes about 6
hours of exposure to 3% hydrogen peroxide to kill them. Acanthamoeba has
been isolated from bottled distilled water commonly found in the grocery
store. It is also found in swimming pools and hot tubs.

Acanthamoeba infection of the cornea is virtually unknown in anybody except
contact lens wearers, whose lenses have become contaminated with water from
the tap, hot tubs, swimming pools, lakes, etc. Acanthamoeba infections are
historically difficult to treat, and a fair number have required corneal
transplants, only to have the graft become re-infected by the organism. I
have seen two cases within the past couple of months. One case had
suffered a self-inflicted eye injury while wearing her contact lens, and
had put ice on her eye following the injury. The source of infection was
presumably the ice made from tap water. The second case reported having
been swimming in a backyard pool while wearing contacts within days of the
infection. Both cases were caught very early, and all the organisms were
eradicated - hopefully.

Do you still want to take the risk?

DrG
 
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George Bray
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      08-06-2004, 07:46 PM
"Dr. Leukoma" <(E-Mail Removed)> wrote in message
> Do you still want to take the risk?


Thank you Dr G and others who have contributed, for your warnings,
which I take seriously.

Commercial saline isn't exactly dirt cheap from UK shops, being about
3 for 500ml.

My final stage would always be a long soak in 3% hydrogen peroxide
(stage 1) solution. After your warning, I will make sure I leave them
for at least 6 hours. I normally leave the lens in hydrogen peroxide
for 8 or 9 hours. Is that enough to eliminate almost all the risk from
using de-ionised car battery water in the first place?

The other risk appears to be damage to the lens plastic if I use the
wrong concentration of salt. So I will endeavor to find out the
concentration used in the medical saline solutions and/or the
concentration of salt in human tears, which I guess is about the same.

Regards
George
 
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George Bray
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      09-05-2004, 11:02 PM
(E-Mail Removed) (George Bray) wrote in message news:<(E-Mail Removed). com>...
> The other risk appears to be damage to the lens plastic if I use the
> wrong concentration of salt. So I will endeavor to find out the
> concentration used in the medical saline solutions and/or the
> concentration of salt in human tears, which I guess is about the same.


I've found out what most people with a medical background would
already know - that human tears have a salt content of about 0.9%,
which happens to be about the same as sea water. Perhaps one could use
sea water as a cheap substitute for contact lens saline solution,
followed by a long soak in hydrogen peroxide to kill any bugs.

I also found that commercial table salt has other additives. These
might not be very good for contact lens, so I will find a source of
sodium chloride with a high level of purity. It should still work out
cheaper than buying commercial saline solution.

Regards
George
 
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Repeating Rifle
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      09-06-2004, 12:32 AM
in article (E-Mail Removed), George Bray at
(E-Mail Removed) wrote on 9/5/04 4:02 PM:

> I've found out what most people with a medical background would
> already know - that human tears have a salt content of about 0.9%,
> which happens to be about the same as sea water. Perhaps one could use
> sea water as a cheap substitute for contact lens saline solution,
> followed by a long soak in hydrogen peroxide to kill any bugs.
>
> I also found that commercial table salt has other additives. These
> might not be very good for contact lens, so I will find a source of
> sodium chloride with a high level of purity. It should still work out
> cheaper than buying commercial saline solution.


While the salt content of physiological (normal has a different meaning in
chemistry) is indeed about 0.9%, The salt concentration in sea wter is much
higher!

Commercial salt is fairly pure. Some additives are there by design. The
crystallization process by itself will lead to purification.

Bill

 
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Dr. Leukoma
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      09-06-2004, 03:22 PM
(E-Mail Removed) (George Bray) wrote in
news:(E-Mail Removed) om:

> (E-Mail Removed) (George Bray) wrote in message
> news:<(E-Mail Removed). com>...
>> The other risk appears to be damage to the lens plastic if I use the
>> wrong concentration of salt. So I will endeavor to find out the
>> concentration used in the medical saline solutions and/or the
>> concentration of salt in human tears, which I guess is about the
>> same.

>
> I've found out what most people with a medical background would
> already know - that human tears have a salt content of about 0.9%,
> which happens to be about the same as sea water. Perhaps one could use
> sea water as a cheap substitute for contact lens saline solution,
> followed by a long soak in hydrogen peroxide to kill any bugs.
>
> I also found that commercial table salt has other additives. These
> might not be very good for contact lens, so I will find a source of
> sodium chloride with a high level of purity. It should still work out
> cheaper than buying commercial saline solution.
>
> Regards
> George



The parameters of the contact lens are determined in a state of equilibrium
with 0.9% saline. Commercially available hydrogen peroxide does not
contain sodium chloride. You would have to resoak your lenses in saline.

Why not just fork over the money and buy the prepared sterile saline
solution and give it up? You are playing with your eyes.

DrG
 
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Repeating Rifle
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      09-06-2004, 07:47 PM
in article Xns955C6ACCF6A89DrLeukoma@207.217.125.201, Dr. Leukoma at
(E-Mail Removed) wrote on 9/6/04 8:22 AM:

> The parameters of the contact lens are determined in a state of equilibrium
> with 0.9% saline. Commercially available hydrogen peroxide does not
> contain sodium chloride. You would have to resoak your lenses in saline.
>
> Why not just fork over the money and buy the prepared sterile saline
> solution and give it up? You are playing with your eyes.


I really get upset by such statements. They are the equivalent of a robber's
"Your money or your life." It is what keeps branded drugs still selling in
the presence of incredibly cheaper generics. Now, if you don't know what you
are doing then pay exxtra for the expertise. The questioner obviously had no
clue.

Bill

 
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Dr. Leukoma
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      09-06-2004, 11:20 PM
Repeating Rifle <(E-Mail Removed)> wrote in
news:BD620D0F.22F45%(E-Mail Removed):

> in article Xns955C6ACCF6A89DrLeukoma@207.217.125.201, Dr. Leukoma at
> (E-Mail Removed) wrote on 9/6/04 8:22 AM:
>
>> The parameters of the contact lens are determined in a state of
>> equilibrium with 0.9% saline. Commercially available hydrogen
>> peroxide does not contain sodium chloride. You would have to resoak
>> your lenses in saline.
>>
>> Why not just fork over the money and buy the prepared sterile saline
>> solution and give it up? You are playing with your eyes.

>
> I really get upset by such statements. They are the equivalent of a
> robber's "Your money or your life." It is what keeps branded drugs
> still selling in the presence of incredibly cheaper generics. Now, if
> you don't know what you are doing then pay exxtra for the expertise.
> The questioner obviously had no clue.
>
> Bill
>
>


Sorry to upset your precarious equilibrium, Mr. Bill. Unfortunately, I
have to treat patients who contract acanthamoeba keratitis from such
contaminated sources.


DrG
 
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