Dry eye preparations Flashcards
what is the most general way to improve dry eyes
using ocular lubricants
how many % of the total ophthalmic drugs do artificial tears contribute to in the UK
33%
why are artificial tears not exactly the same as natural tears
because lots of glands contribute to natural tears which artificial tears can’t mimic
other than functioning as lubricants, what do some more recent formulations mimic
the electrolyte composition of human tears (e.g.TheraTears®)
what are the 3 forms that ocular lubricants are available as and what are they used to treat
- eyedrops
- gels
- ointments
used to treat the discomfort associated with conditions in which the tear film is reduced or unstable
what are lubricant eye ointments also used in the treatment of as well as the discomfort associated with conditions in which the tear film is reduced or unstable
the treatment of recurrent corneal erosions
what are the majority of dry eye preparations available as and who can they be sold and supplied by
over the counter (P medicines, GSL or CE marked products) and can be sold and supplied by optometrists
what are the most commonly used drugs in optometric practice
ocular lubricants
what are the 2 foremost objectives in caring for patients with dry eye disease
- to improve the patient’s ocular comfort and quality of life and
- to return the ocular surface and tear film to the normal homeostatic state
symptoms can rarely be ____________, they can often be __________ with ocular lubricants
symptoms can rarely be eliminated, they can often be improved with ocular lubricant
what did a systematic review conclude about artificial tears
that they improved the condition of the exposed ocular surface in patients with dry eye, based on Rose Bengal staining as the primary outcome measure.
However, there was no statistical difference in the efficacy of the various formulations
list 4 limitations that the treatment of dry eye with ocular lubricants has
- Formulation cannot replace complexity of natural tears
- Administered intermittently rather than continuously as with natural tears. Therefore formulated to increase their contact time e.g. mucoadhesive polymers
- Choice of therapy is determined by the severity of the condition (taking into account the lifestyle and dexterity of the patient)
- The presence of preservatives in artificial tears can compromise the ocular surface following prolonged use
what is the recommended treatment of ocular lubricants for mild dry eye disease
Artificial tears up to 4x per day
what are the recommended treatments of ocular lubricants for moderate dry eye disease
- Unpreserved artificial tears up to 12x per day with lubricating ointment at night
- Tear conservation
what are the recommended treatments of ocular lubricants for severe dry eye disease (name 3)
- Immunotherapy e.g. cyclosporin
- Autologous therapy (serum)
- Tear conservation
what is the name of the recommended immunotherapy treatment for severe dry eye disease
cyclosporin
list the 7 types of formulations that ocular lubricants are available in
- Cellulose esters
- Carbomers
- Polyvinyl alcohol
- Sodium hyaluronate
- Lubricating ointments
- Acetyl cysteine
- Liposomes (liposomal spray)
what type of products are ocular lubricants increasingly available stand what does this stand for
- available as CE–marked products
- These are ‘medical devices’ (similar to contact lens solutions) and therefore not regulated by the Medicines Act
if a product is a medical device which is CE marked, what are they not regulated by
the medicines act
because ocular lubricants are increasingly available as medical devices, what is a limit as a consequence
their availability on NHS prescriptions
what advantage do mucoadhesive properties in ocular lubricants have, and what are they available as
- Increased contact time with the ocular surface
as they are more sticky - available as mucoadhesive viscous gels
- most are polymers (artificial molecules)
what are the side affects associated with mucoadhesive viscous gels
- blurring
- sticky lids
what is the most commonly prescribed formulation of ocular lubricants and name 4 examples
Cellulose esters
e. g.
- hypromellose
- hydroxyethylcellulose
- methylcellulose
- carboxymethylcellulose
which formulation of drugs are viscoelastic polysaccharides
Cellulose esters
what is an advantage of the Cellulose ester formulation of ocular lubricants
Good retention time on ocular surface
what is a disadvantage of the Cellulose ester formulation of ocular lubricants
Can cause crusting of eyelids mimicking blepharitis
what two forms of packaging are the Cellulose ester formulations of ocular lubricants available as
- unit dose preservative free
or - multi dose
which type of ocular lubricant formulation is the cheapest and thus available on the NHS
Cellulose ester
which type of molecule are the ocular lubricant formulation, carbomers
Synthetic polymers
name 2 advantages of the carbomer formulation of ocular lubricants
- Good retention time on ocular surface
- Good viscosity when eyes open shear thin during blinking
what is a disadvantage of the carbomer formulation of ocular lubricants
- Tends to blur vision
what causes the viscosity of tears to be decreased
if applying a force when blinking
what behaviour does the tear fluid display
non-Newtonian behaviour
what are the majority of solutions unaffected by
the shear rate
which type of molecule are the ocular lubricant formulation, Polyvinyl alcohol
Synthetic polymers
Polyvinyl alcohol formulations have low….
viscosity
which type of dry eye is Polyvinyl alcohol ocular lubricant formulations beneficial in
mucin and lipid deficiency dry eye
what is a disadvantage of Polyvinyl alcohol ocular lubricant formulations
Short retention time
therefore need to put in more times
which formulation of drugs are Mucopolysaccharides
Sodium hyaluronate
Sodium hyaluronate is a __________ formulation
Sodium hyaluronate is a vicious formulation
what is the advantage of Sodium hyaluronate ocular lubricant formulations
Good retention time on ocular surface (superior to cellulose esters and PVA)
what 2 other formulations is the retention time of Sodium hyaluronat superior to
- cellulose esters
and - Polyvinyl alcohol
which ocular lubricant formulation is a natural product, which makes it work well as a ocular lubricant
Sodium hyaluronate
what is the disadvantage of the ocular lubricant formulation, Sodium hyaluronate
Tends to blur vision
which ocular lubricant formulation blurs vision less than the Cellulose ester formulation
Sodium hyaluronate
what form do ophthalmic lubricating ointments come as
Liquid paraffin
ophthalmic lubricating ointments have high….
viscosity
what does ophthalmic lubricating ointments contribute to
rebuilding the lipid layer
what does ophthalmic lubricating ointments melt at
the temperature of ocular tissues
what is the advantage of ophthalmic lubricating ointments
long retention time
when is ophthalmic lubricating ointments used at its best
when other artificial tears are used during the day and ophthalmic lubricating ointments used at night
what is a disadvantage of ophthalmic lubricating ointments
Blurred vision
what can be a result of tear modification as a result of dry eye
Mucolytic in filamentary keratitis
which formulation of ocular lubricant needs to be used to treat Mucolytic in filamentary keratitis and at what dose
Acetylcysteine 5-10%
name an example of Acetylcysteine 5-10% used to treat Mucolytic in filamentary keratitis and which type of medicine is it available as
- Ilube
- available as POM
how does the Acetylcysteine 5-10% formulation of ocular lubricant treat Mucolytic in filamentary keratitis
it dissolves mucous filaments by breaking disulphide bonds
what sensation is felt when instilling Acetylcysteine 5-10% into the eye
stinging sensation
the cornea feels rough
what is the purpose of preservatives in ocular lubricants
to prevent bacterial contamination
what is the drawback of preservatives in ocular lubricants
they are toxic to the ocular surface
when do preservatives cause more harm/toxicity to the ocular surface
when they are put into the eye lots of times a day to treat a chronic condition
what is the most common type of ocular preservative found in ocular lubricants and solutions
Benzylkonium chloride BAK
what affect on the eye can 1 drop of Benzylkonium chloride have after 10 minutes
an effect/morphology on the microvilli of the corneal epithelium and on the corneal stroma
what affect on the eye can 1 drop of Benzylkonium chloride have after 6 hours
it strips off microvilli of the corneal epithelium and on the corneal stroma
how are preservative free ocular lubricants generally packaged as and what implications does this have
- as single dose minims
- this is more expensive
what is Benzylkonium chloride BAK taken up by and what consequences does this have
- by soft contact lenses
- and then is released slowly
- exceeding upper safety limits (increases toxicity)
what type of contact lenses absorbs greater quantities of Benzylkonium chloride BAK
High-water content lenses
greater than low water content lenses
which lenses take up a very small amount of Benzylkonium chloride BAK and what implications do they have
- hard contact lenses
- and then is released slowly
- approaching upper safety limits (increases toxicity)
what can tear film concentrations of benzalkonium, such as after eye drop use in the presence of soft contact lenses could result in
adverse effects on the ocular surface
what have newer generation ophthalmic preservatives been developed with
reduced ocular toxicity
name 4 newer generation ophthalmic preservatives
- Purite
- Sodium perborate
- SofZia
- Polyquaternium
what can newer generation preservatives be used with and why
contact lenses
as they’re less toxic
what happens to the newer generation preservative purite after going into the eye
dissociates into water, oxygen, sodium, and chlorine free radicals
what happens to the newer generation preservative Sodium perborate after going into the eye
converts into water and oxygen on instillation
what happens to the newer generation preservative SofZia after going into the eye
it is modified into harmless elements on instillation
which newer generation preservative is more common in multi dose contact lens care products, and is less toxic than BAK
Polyquaternium
name a brand of ocular lubricant that is a multi dose preservative free system and how does it achieve this
Hycosan
by having a valve system in the neck of its bottle
what is the advantage to having a multi dose packaging preservative system
it is more cos effective than single use minims
other than Hycosan, name 3 other multi dose preservative free systems with its available dose
- Hylotear 0.1% hyaluronate
- Hyloforte 0.2% hyaluronate
- Hyabak 0.15% hyaluronate
what impact does a more concentrated dose (%) preservative free multi dose ocular lubricant have
it sticks more to the ocular surface
but then can affect vision
what ingredient does the ocular lubricant Systane contain which causes it to increase its viscosity on contact with the ocular surface
hydroxypropyl (HP) guar
what is the mechanism of the ocular lubricant Systane to increase its viscosity on contact with the ocular surface based on
the change in pH
Systane is a liquid in the bottle at a pH of 7.0, but when placed in the eye (which has a pH of ~7.4), a chemical reaction occurs
how does the ingredient hydroxypropyl (HP) guar in Systane cause it to increase its viscosity on contact with the ocular surface
the HP guar binds to the ocular surface and simultaneously crosslinks with borate ions in the solution, forming a network with a gel-like consistency
what is the ocular lubricant liposomal spray and what does it contain
An aqueous suspension of phospholipid-containing liposomes containing hydrogenated phosphatidylcholine
i.e. a lipid in an emulsion
what type of dry eye has liposomal sprays been beneficial in
evaporative dry eye
how is the liposomal spray formulation used
it is sprayed onto the closed eyelids
what is recognised as a key pathogenetic mechanism of dry eye
inflammation
which anti inflammatory drug was the first commercially available pharmaceutical therapeutic agent for the treatment of dry eye/keratoconjunctivitis sicca
Restasis - 0.05% cyclosporine ophthalmic emulsion
available in US but not UK
how does autologous serum work as a treatment for dry eye
it uses the patients own blood plasma, this is because it is a neutral substance and is very good for the ocular surface
why is autologous serum a good dry eye treatment for the ocular surface
it contains serum and anti-bodies
what other alternative dry eye treatments are there from ocular lubricants
ingestion Omega-3 and Omega-6 fatty acids
where can Omega-6 fatty acids be found
evening primrose oil
which fish contains lots of Omega-3 fatty acids
- mackerel
- tuna
- cod liver