Safe use of cheap distilled water to clean contact lens

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

 

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

Somewhat. The problem is keeping it sterile.

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

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

-- Robert

 

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

 

(George Bray) wrote in

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

 

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

 

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

 

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

 

(George Bray) wrote in

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

 

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

 

I was not suggesting that people who have no clue do their own thing. It is
just that I do get upset at being talked down to. I do get upset with a
charge of many dollars for small amount of physiologic saline solution when
most of the cost is in the packaging. Because it is a considerable amount of
trouble to prepare it, I am happy to buy it--but at the 99¢ store.

Bill

 

Don't forget the added costs of manufacturing in a highly regulated FDA
environment. I'm a chemist, and I certainly know how to make normal
saline. I am also knowledgeable enough in microbiology to know that spores
are difficult to kill, even with boiling. Did you know that it takes
several hours of exposure to 3% hydrogen peroxide to kill acanthamoeba
spores? To me, it isn't worth the risk, and I buy my saline just like
everybody else.

DrG

 

Dr G

Thank you for your inputs. I respect your views, and know you're right
even if I decide to take a calculated risk with my own eyes.

Many eye care professionals encourage their patients to have laser eye
surgery, and I think that's 1000 times more risky than what I'm
proposing:

1. Prepare a 0.9% saline solution from de-ionised car battery water
which can be left hanging around under the kitchen sink for years. It
may have lots of bugs but I'll get rid of some of those by boiling the
water for 10 minutes in a saucepan with the lid on, before adding
relatively pure sodium chloride.

2. Use the DIY saline with a protein removal tablet. I need to do
this so infrequently, that I would end up buying a new bottle of
saline every time - a waste of money.

3. Leave the lens to soak in 'stage 1' 3% hydrogen peroxide solution
for 8 or 9 hours, at least, and then neutralise.

4. Put the cleaned and disinfected lens in my eye.

On the other hand, perhaps I can avoid all this by dissolving the
protein removal tablet in 'stage 1' 3% hydrogen peroxide solution, and
avoid any need to use saline in the first place. Do the tablets work
perfectly well in stage 1 solution do you know?

Regards
George

 

I don't get upset by these statements. The amount of money to be saved is
nearly inconsequential, and the cost of treatment when something goes
wrong is major. Most people do not need to wear contacts. Thus, I feel
that most people who aren't willing to take the extra time, effort and
money that contacts take, should stick to glasses.

And the same people who don't know what they are doing, are often the same
people who don't realize it.

Many people who read this group (like me) are layfolks. A clear warning
not to try to make your own contact lens solutions is appropriate, in my
mind. Those who have the expertise can determine for themselves whether
they wish to take this advice or not.

 

IIRC, there are protein removal tablets that are designed
for use in 3% H2O2. Not all will necessarily work because
peroxide is a strong oxidizer and may react with the remover.

-- Robert

 

I thought that the approach to tackling resistant spores was to encourage
their initial growth and then zapping them with heat. Has this changed over
the years?

Bill

 

The cornea is a good culture medium. Then, when all of the spores have
converted into trophozites, a transplant is performed.

DrG

 

(George Bray) wrote in

Let me point out the problems with this scenario. First of all,
acanthamoeba spores have been found in both deionized as well as distilled
water commercially available. I haven't researched this lately, but
boiling the water for 10 minutes probably will not be sufficient. You may
have to autoclave it, i.e. use a pressure cooker. YOU NEED TO FIND THIS
OUT FIRST.

Then - and I think you have already spotted the next logical flaw - what is
the purpose of the saline if you are going to subsequently soak your lenses
in 3% hydrogen peroxide? How will you remove the peroxide before inserting
the lenses into your eyes without compromising the sterility?

My recommendation is that you purchase commercially available sterile
saline. Normal saline has many applications in medicine, including
respiratory therapy. There may be more cost-effective alternatives if you
purchase in bulk.

DrG

 

Thank yor for your latest suggestions and sound warnings.

The only purpose of the saline is to dissolve the protein removal
tablets, as I thought saline is the best solvent for the tablets. If
commercial 3% hydrogen peroxide solution is just as good, then I could
use that and will not need any saline. But is hydrogen peroxide
solution just as good for the protein removal tablets?

You ask how I will remove the peroxide before inserting the lenses
into my eyes, without compromising the sterility?

I assumed that after 9 hours soaking in the peroxide, I am at exactly
the same stage in a cleaning/disinfection cycle as anyone using
2-stage peroxide based systems. After removal from the peroxide, I
will place the lens in neutralising solution for at least 10 minutes,
before placing the lens in my eye.

Regards
George

 

You'll have to read the directions on everything to find out how they
work. I have used two different kinds of protein removal tablets. The
first kind came with little plastic cups and you dissolved the tablets in
saline. The second kind went directly into the hydrogen peroxide
disinfectant. If I remember, the second kind was easier to use but cost
more.


I buy all my stuff at Costco. It is quite cheap, considering how long it lasts.