Allergy & Dry
Allergies are often associated with
ocular surface disease and in particular with dry eye syndromes. For the
least, it is likely that the reduced quantity or quality of tears increases
the quantity of allergens, limits their evacuation through the canaculi
and increses inflammation which is a known aggravating factor for
allergies. The prevalence of allergic persons among dry eye sufferers and
particularly with blepharitis, rosacea and meibomitis seems to indicate
that there is some connection in many cases. Some authors suggest that
severe allergies may cause a permanent dry eye state and sometimes; the
exact frontier between the 2 pathologies is unknown. But it's obvious
that both cause inflammation and both aggravate each other. In any
case, we may say that allergy further complicates diagnostic and care of
ocular surface diseases.
Ocular Allergy in its mildest forms
is more and more prevalent and surely one of the most common conditions.
It's probably the result of the increase of allergy sufferers altogether
but surely other factors such as internal (in-house) and external
pollution, the catastrophic management of human environnement, etc. The
causative agents are pollens, acarians, some chemical substances
provoking intolerances, cosmetics, furs and animal hair, etc. Let's
mention two examples of catastrophic management of our new
environnement: It is obvious that if some many persons are
allergic to plane trees in European cities it's probably because of the
omnipresence of that tree in our polluted cities and bordering our roads.
Another example is new species, such as rag weed (ambrosias), which colonize
new territories and become omnipresent, or excessive planting of cyprus
trees by man for ornamentation. For the first time, a babyborn was granted
the righ to uproot trees that were threatenning his life in Connecticut.
A better management and planting various/different breeds, as much as
possible non-allergenic trees, will surely be part of the solution if
when want to avoid the increased incidence of allergy in our modern cities. On
the left, a picture of an eyelid presenting allergic sign including
papillary reaction by
Dr Edouard Benois.
In any case, ocular allergy, as all
allergies are immunitary reactions to the excessive production of IgE
and liberation of histamine, prostaglandins, leucotriens and kinins.
The body (and in this case) the eye will interpret the presence of the
allergen as an aggression.
Two types of allergy are predominant
(more that half of all cases) and are associated with high IgE levels in
conjunctivitis, is an inflammatory reaction or the conjonctiva (the slim
transparent membrane covering the eye and the
interior of the lids. It is similar to allergic rhinitis, with which it
shares many features and sometimes even a link. The main symptoms are: red
eyes, stinging, grittiness, irritation, photophobia and tearing. The
lids are also often swollen and red and sometimes chemosis (conjonctival
swelling), dark circles around the eyes. In some cases, mucus secreation
may be very important. it usually doens't affect the cornea. It's
less serious and surely the most frequent types of ocular allergy. This
type of allergic reaction is often the result of the presence of pollens
in the spring and summer (tree pollens and grasses).
Perannual conjonctivitis last all
year long and is often due to the presence of allergens such as acarians
or animals in the house of the patient. It's frequently a mild form of
allergy and an annual variant of the allergic conjonctivitis. The
symptoms are the same.
But there are rarer and surely more serious
forms of ocular allergy. These are usually totally unknown by the general
population. These are allergies seem to combine both a Type I and Type II
Vernal (kerato)conjonctivitis is essentially
a male and infantale form of ocular allergy (it usually disappears after
adolescence). It's a serious form of allergy, since it sometimes causes
ulcerations leading to extensive and definitive loss of sight. The
ulcerations will usually appear in the upper part of the cornea and
papillary hypertrophy of the upper lid.
Atopic (kerato)conjonctivitis is found in
patients having an atopic tendency (eczema, asthma and other allergic
sylptoms, at least 40% of the patients have allergic dermatitis), it's
usually a male subject of 30 to 50 years. it's a very serious form of
allergy that leads to ulcerations and possibly extensive and definitive
Giant-papillary conjonctivitis is
often seen in contact lens wearers (or due the presence of a foreign
body in the eye). Preservatives in eye drops or contact lens solutions
may cause these severe allergic reactions. It provokes serious papillary
hypertrophy of the lids (mainly the upper ones).
These may also have an
impact on the eye surface.
Eczema: is an allergic
reaction caused by many allergens including preservatives in eye drops
or make up.
is an inflammation of lids caused by allergies (pollens,
drugs, creams and make-up), which ocular consequences are often
disregarded. As with any blepharitis, it may cause meibomitis and
further disturb the lipid layer of tears and further disrupt stability
of tears altogether. On the left, a picture of an eyelid
presenting eczema by
Dr Edouard Benois.
impact of preservatives in eye drops
Allergic and toxic, preservatives may
alter the eye's epithelium, in particular benzalkonium and thiormersal.
This allergenic activity particularly concerns all ocular surface
sufferers who have to use many drops. Preservatives may cause severe
allergic reactions. A similar problem is sometimes noticed in contact
lens wearers where
preservatives in decontamination solutions are usually the culprits.
Beyond allergy many studies show that cytotoxicity (a
different and delayed type of immunitary reaction
that occurs without any
obvious short term signs) and tear film disruption caused by
preservatives are likely to inscrease corneal erosions.
This situation is particularly absurd
when so many drops for ocular allergies containt preservatives (notably
benzalkonium) which are allergenic, inflammatory and irritant for eye
surface. The limited choice of unpreserved antihistaminic eye
drops is obvious challenge for dry eye sufferers.
our site dedicated to preservatives in eye drops:
Preserve our Eyes, not our Drops!
See our following pages on
ocular allergy testimonials
contacts on allergy and air quality
How is it possible to explain the
exponantial rise and incidence of ocular allergies?
As with dry eyes, probably a better diagnostic, improved
screening of patients and attentive doctors to patients complaints has permitted
to unravel more cases of allergies and probably milder cases that would have
remain disregarded until they became very disabling. But this does not
explain such a rise and one must look for additional
changes in our way
of life and food habits
to justify this.
The role of
The main cause of allergy is the allergen itself of course, but
since it has existed all along, there are surely other aggravating factors to
justify this current prevalence. Certain authors point out in-house and air
pollution, which could trigger, amplify and catalyse allergic reactions.
The exact mechanism is unknown but
three leads are usually suggested:
Immunotoxicity - the pollution in
this configuration, would be a co-factor of allergie by inter-acting with the
allergen inscreasing the immune reaction.
Pro-inflammatory effect - pollution
creates an inflammatory reaction which could serve has mediator for allergy
facilitating and inscreasing it.
By inscreasing the allergen's allergenicity - pollution is then
accused of modifiying the allergen itself and amplifying their release in the
case of pollens.
This could explain the importance
of allergies in urban areas whereas
pollens are more present in rural areas. As such, quantity
alone may not explain the inscrease of allergies in urban areas. Another
immunitary reaction beyond allergy may be involved in the process: the
complement system which has a key role in inflammatories processes
and immunitary responses.
- Pollution et
Allergies Oculaires - Volume2, Système du
complément et allergies, Collection Librairie Médicale Théa.