Further sources:
References
English FP, Nutting WB (1981),
‘Demodicosis of ophthalmic concern’
Am J Ophthalmol, 91:362–372.
1
Lee SH, Chun YS, Kim JH, et al. (2010),
‘The relationship between demodex and
ocular discomfort’, Invest Ophthalmol
Vis Sci. 51:2906–2911
2
Spickett SG (1961), ‘Studies on Demodex
folliculorum’, Parasitology, May, 51:181-192.
3
www.bbc.co.uk/earth/story/20150508-
these-mites-live-on-your-face
4
Turk M, Ozturk I, Sener AG, et al. (2007),
‘Comparison of incidence of Demodex
folliculorum on the eyelash follicule in
normal people and blepharitis patients’,
Turkiye Parazitol Derg. 31:296–297.
5
Liu J, Sheha H, Tseng SC (2010),
‘Pathogenic role of Demodex mites in
blepharitis’, Curr Opin Allergy Clin
Immunol, 10:505-10
6
Despite the patient exiting the first
treatment session with perfectly clean-
to-the-base lashes, the CD’s return to
the extent that they appear similar to
the pre-treatment visit. As the treatment
weeks advance, there is progressively
less returning CD to deal with. Because
TTO or T4O usage promotes outward
migration of Demodex, the quick
reformation of CD after opening the
follicles is expected, as Demodex are
being purged. With a decreasing active
population of Demodex, the amount
of CD being formed also reduces and
this is conformational the treatment is
working. We have noticed a proportional
relationship between the amount
of resurgent CD and the initial
pre-treatment CD count.
Innovative treatment
Tea tree oil contains chemically sensitive
substances. Several oil constituents
oxidize on contact with air at room
temperature, especially when there’s
light, too. In this way, air greatly
reduces the terpinen-4-ol content.
What’s worse is that the gradual loss
of active constituents is accompanied
by a dramatic rise in the concentration
of substances, such as p cymol, ascaridol
and 1,2,4-trihydroxymenthane,
which irritate the skin and can cause
allergic reactions.
One way out of this predicament is the
molecular inclusion of T4O in a suitable
cyclodextrin – a method that has proved
effective for fragrances, vitamins,
and other lipophilic substances.
Cyclodextrins are ring-shaped sugar
molecules comprising several interlinked
glucose units. Each cyclodextrin
molecule can house a lipophilic guest
molecule in its cavity, and will release
it again under suitable conditions. It is
best to imagine a cyclodextrin molecule
as a tiny safe in which an individual
molecule is kept and protected against
the influence of oxygen, light and heat.
When necessary, the safe is opened
16
etCETera | June 2016
and the molecule emerges completely
unchanged – as fresh as when it was
put inside. The key to opening these
molecular safes is moisture.
For as long as the T4O remains
enclosed in the cyclodextrin, it enjoys
perfect protection – it can neither
evaporate nor be altered chemically.
The skin’s natural moisture and
temperature are sufficient to release
the T4O. The T4O thus reaches the
skin in juvenile form. There are no skin
irritating and sensitising oxidation and
degradation products.
Accelerated treatment
To improve patient outcomes for
severe cases, we have tried a slow
release version of T40 entrapped
in Cyclodextrin on four patients, to
deliver 10% T4O active over 12 hours.
The product particles are around
5000nm in size, which is far too large
for deep follicular penetration and
resemble talcum powder. Applied onto
the eyelids and lashes before sleep
it is absent upon wakening. Patients
report no irritation whatsoever. We
have observed a greater production
of resurgent CD, which may imply a
quicker evacuation of Demodex.
Another agent, related to limonene
and a by-product of the orange juice
industry is also miticidal but has not yet
been commercialised. There is scope for
further product development.
Currently, Demodex treatment is an
arduous process for both practitioner
and patient. The time burden,
commitment required and commercial
revenue lost in the disruption of the
provision of spectacles and contact
lenses makes this work unattractive for
most practices. However the professional
reward in curing a condition where
others have failed is priceless and the
patients are extremely grateful.
About the author
David Crystal transferred from an
undergraduate degree course in
Physics with Computing at Bradford
University to study Optometry at
Caledonian University Glasgow in
1980. He established Scotland’s
first specialised dry and watery
eye clinic, with routine punctal
occlusion and tear duct syringing
procedures. David gained his
Post Graduate Diploma in Ocular
Therapeutics in 2002, becoming the
first of his kind in Scotland. He now
occasionally facilitates workshops
for Glasgow Caledonian University
Ocular Therapeutics course. David
is currently pursuing treatments
that eradic ate Demodex; the most
common indirect cause of evaporative
dry eye. Outside of optometry,
his interests are snowboarding
and website SEO. He also created
EyeDispense, Just Reading Test Types
and Maddox Rod iPad apps.
7
heirkhah A, Casas V, Li W, et al. ‘Corneal
K
manifestations of ocular Demodex infestation’.
English FP, Nutting WB (1981),
‘Demodicosis of ophthalmic concern’,
Am J Ophthalmol, 91:362–372.
8
Bonnar E, Eustace P, Powell FC (1993),
‘The Demodex mite population in rosacea’,
J Am Acad Dermatol. 28:443–448.
9
Huang Y, He H, Sheha H, Tseng SCG
(2013), ‘Ocular demodicosis as a
risk factor of pterygium recurrence’.
Ophthalmology, 120:1341–1347.
10
Gao Y-Y, Di Pascuale MA, Li W, et al.
(2005), ‘High prevalence of ocular
Demodex in lashes with cylindrical
dandruffs’. Invest Ophthalmol Vis Sci.
46:3089–3094. [PubMed]
11
Nichols KK, Foulks GN, Bron AJ, et al.
(2011), ‘The inter- national workshop on
meibomian gland dysfunc- tion: executive
summary’ Invest Ophthalmol Vis Sci.
52(4):1922-9.
12
Gao Y-Y, Di Pascuale MA, Li W, et al.
(2005), ‘High prevalence of ocular
Demodex in lashes with cylindrical
dandruffs’. Invest Ophthalmol Vis Sci.
46:3089–3094. [PubMed]
13
Tighe et al. (2013), ‘Terpinen-4-ol is the
Most Active Ingredient of Tea Tree Oil to
Kill Demodex Mites’ http://www.ncbi.
nlm.nih.gov/pmc/articles/PMC3860352/
14
Gao YY, Xu DL, Huang lJ, Wang R, Tseng
SC. (2012), ‘Treatment of ocular itching
associated with ocular demodicosis by
5% tea tree oil ointment’, Cornea. Jan.
31(1):14-7. [Medline].
15
Simpson et al. (2004) ‘Prevalence of
botanical extract allergy in patients with
contact dermatitis’, Dermatitis 15:67-72.
16
Kheirkhah A, Blanco G, Casas V, Tseng
SC (2007), ‘Fluorescein dye improves
microscopic evaluation and counting of
demodex in blepharitis with cylindrical
dandruff’, Cornea. Jul. 26(6):697-700.
[Medline].
17
English FP, Cohn D, Groeneveld ER.
(1985), ‘Demodectic mites and chalazion.
Am J Ophthalmol’, 100:482–483.
[PubMed]
Kheirkhah A, Casas V, Li W, et al. (2007),
‘Corneal manifestations of ocular Demodex
infestation’, Am J Ophthalmol. 143:743–749.
Kim J, Chun Y, Kim J. (2011), ‘Clinical
and immunological responses in ocular
demodecosis’, J Korean Med. 26:1231–1237.
Knop E, Knop N, Millar T, et al. (2011),
‘The international workshop on meibomian
gland dysfunction: report of the
subcommittee on anatomy, physiology, and
pathophysi- ology of the meibomian gland’,
Invest Ophthalmol Vis Sci. 52(4):1938-78.
Koksal M, Kargi S, Taysi BN, Ugurbas
SH. (2003), ‘A rare agent of chalazion:
demodectic mites’, Can J Ophthalmol.
38:605–606. [PubMed]
Liang L, Safran S, Gao Y, et al. (2010),
‘Ocular demodicosis as a potential cause of
pediatric blepharoconjunctivitis’, Cornea.
29:1386–1391.
Obata H. (2002), ‘Anatomy and
histopathology of human meibomian gland’,
Cornea. 21(7 Suppl):S70-4 24.
Wertz PW (2009), ‘Human synthetic sebum
formulation and stability under conditions
of use and storage’, Int J Cosmet Sci. Feb,
31(1):21-25
David Crystal can be contacted at
www.crystaloptometry.co.uk
June 2016 | etCETera
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