Solutions

Question 1

Examples: Preservative/Disinfectants (2)

Answer 1

Polyhexanide

Peroxide

Question 2

Purpose: Preservative/Disinfectants (3)

Answer 2

Restricts growth of micro-organisms

Maintains sterility

Breaks down cellular wall of bacteria (can also do to epithelium)

(failure to disinfect is major cause of microbial keratitis)

Question 3

Examples: Chelating Agents (1)

Answer 3

Ethylene Diamine Tetra-acetic Acid (EDTA)

Question 4

Purpose: Chelating Agents (3)

Answer 4

Enhances preservatives (especially against gram -ve bacteria)

Prevents bacterial growth (binds ions)

Reduces protein build up

Question 5

Examples: Buffer (1)

Answer 5

Boric Acid

Question 6

Purpose: Buffer (2)

Answer 6

Balances acid/alkaline concentration - stabilises pH

Average tear pH is 7.45 but buffer aims for 6.6-7.8

Question 7

Example: Isotonic Agent (1)

Answer 7

Sodium chloride

Question 8

Purpose: Isotonic Agent (4)

Answer 8

Maintains tonicity to match tears

About 0.9% sodium chloride

Too high tonicity = hyperaemia & dehydration

Too little tonicity = oedema

Question 9

Examples: Viscosity Agent (1)

Answer 9

Polyvinyl Alcohol (PVA)

Question 10

Purpose: Viscosity Agent (3)

Answer 10

Increases thickness

Increases contact time with lens

Found in artificial tears

Question 11

Examples: Wetting Agents (1)

Answer 11

Polyvinyl Alcohol (PVA)

Question 12

Purpose: Wetting Agents (2)

Answer 12

Conditioning

Reduces wetting angle = better spread of tears & solution across surface

Question 13

Examples: Surfactants (1)

Answer 13

Polaxamine

Question 14

Purpose: Surfactants (2)

Answer 14

Reduces surface tension

Easy removal of debris and pathogens

Question 15

Example: Stabiliser (1)

Answer 15

Phosphonic Acid

Question 16

Purpose: Stabiliser (1)

Answer 16

Maintains cohesion within a solution (can become unstable over time)

Question 17

Examples: Enzymes (2)

Answer 17

EDTA

Aldox

Question 18

Purpose: Enzymes (2)

Answer 18

Removes deposits

Breakdowns protein bonds

Question 19

Current Preservatives: (3)

Answer 19

Polyquaternium

Polyhexanide

Polyquaternium-1

Peroxide

Question 20

Polyquaternium (polyquats) (2)

Answer 20

Large molecule size does not penetrate soft lens material

Less toxic to ocular surface

Question 21

Polyquaternium-1 (polyquads) (2)

Answer 21

Minimal toxicity

Less efficient against fungai - aldox included to aid this

Question 22

Polyhexanide (dymed) (3)

Answer 22

Lighter than polyquads

Effective against bacteria

Risk of allergies with sensitive wearers

Question 23

Pathogens (Example): Gram Positive Bacteria (1)

Answer 23

Staphylococcus Aureus

Question 24

Pathogens (Presents): Gram Positive Bacteria (3)

Answer 24

Keratitis

Conjunctivitis

Blepharitis

Question 25

Pathogens (Example): Gram Negative Bacteria (1)

Answer 25

Pseudomonas Aeruginosa

Question 26

Pathogens (Presents): Gram Negative Bacteria (2)

Answer 26

Keratitis/Ulceration Conjunctivitis

Question 27

Pathogens (Example): Virus (2)

Answer 27

Herpes Simplex HIV

Question 28

Pathogens (Presents): Virus (2)

Answer 28

Keratitis/Ulceration Conjunctivitis

Question 29

Pathogens (Example): Fungi (1)

Answer 29

Candida Albicans

Question 30

Pathogens (Presents): Fungi (1)

Answer 30

Keratitis/Ulceration

Question 31

Pathogens (Example): Amoeba (1)

Answer 31

Acanthamoeba

Question 32

Pathogens (Presents): Amoeba (1)

Answer 32

Keratitis/Ulceration

Question 33

Five aims of a contact lens care system (5)

Answer 33

Non-toxic Compatible Effective Simple Affordable

Question 34

Non Toxic:

Answer 34

Should not damage or irritate ocular surface

Question 35

Compatible:

Answer 35

Should perform well with lens type it was designed for

Question 36

Effective (3)

Answer 36

Remove deposits & build up Decontaminate/disinfect the lens Optimise vision & comfort

Question 37

Simple

Answer 37

Easy to use and encourage compliance

Question 38

Affordable

Answer 38

Avoid non-compliance and reuse/sparingly use solution

Question 39

Reasons for solution compliance issues (6)

Answer 39

Cost Convenience Ignorance Denial Bad advice (from friends) Lack of incstruction/forgetting

Question 40

Peroxide (2)

Answer 40

Effective against bacteria and fungi Low concentration used