Everyone is to some
extend. The main criteria to evaluate the risk is the frailty of the
corneal epithelial cells, the quality/quantity of
the tearfilm, the duration of the treatment,
the type of preservative used, the dosage of the specific preservative,
the residence time of the preservative in contact with the eye.
But as always, there
are predisposing factors that aggravate the risk, among which are:
Chronic eye diseases: Because these require
long-term treatments and usually several eye drops that contain
preservative over several months or years. Among which are:
Dry eyes: Because dry eye are more fragile and
prone to allergies, because they don't have enough tears to drain
the preservative and protect
the eye from preservatives, the consequences of preservatives are
exacerbated in a dry eye state. Any type of dry eye state, regardless of
the cause, will increase the residence time of preservatives and thus
increase risks.
Glaucoma: Glaucoma eyedrops have usually been
preserved and require long-term if not lifetime treatments
therefore increasing the risk.
Allergic conjunctivitis: Some people are
allergic all-year long or during long periods of the year and therefore
require the use of eyedrops that in some cases are not available without
preservatives. Furthermore, people with an atopic/allergic
predisposition are more prone to develop some kind of sensitivity to
preservatives.
OSD: Severe OSD such as some Dystrophies
(where there is epithelial adhesion issues), Neurotrophic corneas (even
mild forms such after LASIK for instance), Recurrent Corneal Erosions,
Persistent Epithelial Defect, and basically any type of fragile cornea
are more prone to develop ulcers during the use of preserved drops since
preservatives increase epithelial cell apoptosis (death).
Contact Lens
Use: Contact lens materials tend to absorb preservatives. That's
why in preserved drops inserts it is usually advised to remove the
lenses and wait 15 minutes at least after removing the lenses to put
them on again. The preservative substance is then released onto the eye
over very long periods.
But another phenomenon is in cause:
Contact lenses are sometimes impregnated with preservative substances
used in contact lens solutions do reduce contamination risks. These are
necessary in the case of contact lenses but it may be useful to
meticulously rinse contact lenses with a non-preserved solution before
putting the lenses in eye to reduce the amount of preservative released
in eye surface. A very interesting study was
published in the French magazine "60
millions de consommateurs, institut national de la consommation de
Janvier 2007, n°412 dénommée
Toxiques et pas toujours
efficaces par le docteurs/Produits pour lentilles de contact: Toxiques
pour les yeux? en pharmacie Erwan Le Fur & Christian De Thuin".
The study analysed the 10 most used contact lens solutions (particularly
so-called all in one solution) and the main conclusions relevant to the
issues addressed in this website are:
·
Their antibacterial activity is not always
sufficient!
·
The presence of preservatives (especially
since the package inserts don't warn users to rinse the lenses with
non-preserved unit-dose saline solutions) put users at-risk of
developing dry eyes and other intolerances. Furthermore, they have toxic
effects [this should come as no surprise for our readers!]. Therefore,
it was advised to rinse the lenses before wearing them!
·
The contamination risk is increased by 80%
in contact lenses users.
·
All the products are toxic in vitro!
·
The inserts should contain the
recommendation to rinse the lenses with a non-preserved unit-dose before
wearing them.
·
Avoid cigarette smoke! [because cigarette
smoke impregnates lenses as well and is toxic!].
If you wear contact lenses, we advise to
get a copy of this study.
This is what we call the 'Preservative Paradox!
Preserve
our Eyes, not our Drops!
▲
copyright ©
Keratos 2007
