Dry Eye Preparations Flashcards
(42 cards)
What percentage of agents recommended by optometrists involved in MECS were ocular lubricants?
30%
What forms do ocular lubricants come in?
Eye drops, gels and ointments
Why should ocular lubricants not be called artificial tears?
They do not mimic the electrolyte composition of human tears
What exactly does ocular lubricants treat?
Discomfort associated with a reduced or unstable tear film and also with recurrent corneal erosion
Are ocular lubricants a P medicine?
No, it is a CE-marked medicine products and therefore can be sold and supplied by optometrists
Are ocular lubricants regulated by the Medicines Act?
No, it is a medical device
What is the main Management for step 1 dry eye?
Ocular lubricants
What are two main dry eye managements for step 2 of dry eye?
Non-preserved lubricants and non-medicated ointment at night
What is the main objective of ocular lubricants?
Improve patient’s ocular comfort and quality of life
What are five example of aqueous substitutions?
- Cellulose esters
- Carbomers
- Polyvinyl alcohol
- Sodium hyaluronate
- Hydroxypropl Guar
What are some issues with more adhesive ocular lubricants?
Although they have a longer contact time with the ocular surface, they can cause blurry vision and for the eye lids to stick together
The tear has non-newtonian behaviour, what does this mean?
Tears change viscosity when under stress (does not follow newton’s viscosity law)- when the sheer rate is low then the viscosity increases
What is the sheer rate?
the rate of change of velocity at which one layer of fluid passes over an adjacent layer
What are pros & cons of cellulose esters?
- Good retention time
- Blurred vision
- Crusting of eyelids
What are the two formulations of carbomers?
Carbomer 980 and carbomer 940
(Can come in a tube called GelTears)
What is a carbomer?
Synthetic polymer with a good retention time and good viscosity by displaying non-newtonian shear thinning
What are some features of Polyvinyl Alcohol?
- Synthetic polymer
- LOW viscosity
- Good for mucin and lipid deficiency
- Shorter retention time
Is sodium hyaluronate a synthetic polymer or naturally occurring polymer?
Naturally occuring (Muccopolysaccharide)
What are some properties of sodium hyaluronate?
-Viscous formulation
- Good retention time
- Exhibits non-newtonian shear thinning properties
- Blurs vision
- Avilable as single and multidose
What is different about hydroxypropyl-guar?
It incraeses its viscosity after contact with the ocular surface due to a difference in the pH which cuases the chemical reaction to take place
Why are preservative added into ocular lubricants?
Exposure to the atmosphere leads to increased risk of microbial contamination
What is an issue with ocular lubricants with preservatives?
Increased risk of corneal toxicity and damage to the cornea
Which patients in particular would you recommend preservative free eye drops to?
If they use the drops more than 6 times a day and if they are using multiple preserved formulations
Why are preservative ocular lubricants NOT compatible with contact lenses?
Benyzlkonium chloride is taken in by the CLs and slowly released and then released slowly and artificially increased the preservative contact time with the ocular surface which is more so true with high water content lenses