cleaning lens case with tap water?

Someone told me that it is dangerous to clean your contact lens case with
tap water.. (assuming afterwards, you let it stand to dry for many hours).
I figured the organizims would be dead and dried up if you let it dry
completely anyways. Also, what miniscule amounts of organisims are left,
wouldn't they be killed off by the solution?

I've also heard that you must boil your lens case every week to keep it
clean, but wouldn't the solution act as a sterilizer anyways and kill off
whatever is in there?

Thanks, Ian

 

I had that very thought in mind, Ian, when I posted my original
question here this morning about what's the best way to clean lens
cases--that if you leave a case wet with water, bacteria could end up
growing in the moisture. When I rinse my case and leave it
upside-down on a paper towel to dry, I notice that the inside bowls of
the case are almost instantly dry (they are so smooth that water
apparently won't stick to them), but moisture occasionally remains on
the inside of the caps (around the crease of the rim) even 24 hours
later.

Many pathogens can survive for a time on dry surfaces (I assume
because their cell walls or protein coats seal in their own water). I
don't know if any of the ones that cause eye infections do.

I've been thinking that exact same thing too. If there are any
leftover bacteria, I would think that the solution would kill them
off. If, however, as Mike pointed out, a fungal film begins to form
on surfaces that the solution doesn't normally soak, I could see how
bacteria could survive protected on or inside the film, and perhaps
get transferred to the lenses or your fingers when they are removed
from the case.

If any doctors reading this know of a published study that discusses
the mechanism through which old lens cases cause infection, I would be
very interested to read a summary. I wonder if it is only people who
are not careful about rinsing their cases who experience such
problems, or if it is inevitable that any case will eventually become
unsafe to use.

Lothar

 

I am a slob. When they came out with that study showing that children
raised in, um, untidy homes got fewer colds and other infections than
those raised by the neat-freaks I told everybody I knew "SEE?"

That being said, I rinse my case in cold water (it takes forever for the
hot water to get to the tap), let it dry upside down loosely wrapped in a
paper towel, and use the same case for months. If I were worried about it
I'd soak the case in a mild bleach solution every once in a while and
rinse well. I do, however, always wash my hands with disinfectant soap
before inserting or removing my lenses. I'm lazy, not stupid!

--
Cheers,
Bev
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
"Even Islamic terrorists don't hate America like liberals do.
They don't have the energy. If they had that much energy,
they'd have indoor plumbing by now." -- Ann Coulter

 

The problem is that the organism Acanthamoeba is present in tap water and
this can
lead to a rather nasty keratitis, which if not treated promptly can be sight
threatening.

If acanthamoeba is present in the case, if you leave it to dry out then the
organism goes into
a cystic state which preserves against any further dessication and survives
until it is
rehydrated. The problem is that in its cyst form it is resistant to nearly
all MPS solutions,
except in very high concentrations. The only methods of disinfection that
are really effective
are heat or hydrogen peroxide.

Regards


Ian Hodgson - Isle of Man

 

Thanks, Ian, that's exactly the kind of info I was looking for! That
reinforces my idea to rinse my case with hydrogen peroxide or alcohol.
I suspect that alcohol is none too good for the eyes if a drop makes
contact accidentally, but can anybody tell me what hydrogen peroxide
would do? I expect that neither one would leave any sort of residue
in an air-dried case anyway, so this shouldn't even be a concern.

Lothar

 

Okay, thanks Mike. So it sounds like peroxide should be perfectly
fine to use as a lens case rinse. I wonder if 70% isopropyl alcohol
would be just as appropriate for sanitizing. It would certainly
evaporate faster.

Lothar