Contact lens care regimens Flashcards
Directly contribute to product efficacy
Active ingridients
Additional ingredients to produce a usable product
Excipients (non active ingredients)
chemical agent that gives form or consistency to the drug preparation but with limited use in ophthalmic preparation:
Excipients - non active drug ingredients
Non-active agent that dissolves the active form of the drug, controlling its viscosity and aids the transport of the active drug:
ophthalmic vehicle
non-active ingredients (Excipient):
- Water
- Salts
- Viscosity enhancing agents
- Buffer systems
- Measure of the relative amounts of hydrogen ions
- Method of expressing the strength of acids and bases (acids <7>bases)
pH
Is a molecule that includes a positively charged hydrogen ion (H+) as part of its chemical structure and can transfer this ion to another molecule
ACID
- Is a molecule that has a negatively charged hydroxide group (OH-) within its chemical structure and can accept hydrogen ion from an acid
BASE
Average pH of tearfilm:
7.4
pH range of contact lens solutions:
6.5 - 8.0
One or more chemical compounds that when dissolved resist drastic changes in pH
Maintains the Ph of contact lens solutions
Buffer
buffer systems:
Borate - boric acid (B&L) / sodium borate (Alcon optisoft)
Citrate - sodium Citrate / Citric acid (Alcon optifree)
Phosphate - Sodium phosphate / phosphoric acid (Allergan)
A chemical term which describes a solution’s total salt concentration
Usually expressed in milli-osmoles per kilogram (mOsm/kg)
Osmolality
average tear film osmolality
302 mOsm/kg
Describes a solution’s effect on the “tone” or shape of a cell
Tonicity
SCL retain their original shape in an _____ solution
Isotonic
A ______solution causes SCL to lose water and shrink
Hypo-tonic
A ________ solution causes the SCL to gain water and expand
Hyper-tonic
improves the wetting time and comfort of the solution
Increases the thickness of the solution
Viscosity Agents
Preservatives (bacteriostatic):
- Thimerosal
- Sorbic acid & EDTA
- BAK (benzalkonium chloride)
- Dymed
- Chorhexidine
- Polyquad
- Effective against lipid
- Remove loosely bound protein
Surfactant cleaner
Lubricants / artificial tears in ophthalmic solutions:
Methylcellulose
Carboxy-methylcellulose
Hydroxy-methylcellulose
polyvinyl alcohol - PVA
polyvinyl pyrrolidine - PVP
Lubricants in Ointment:
White petroleum
Mineral Oil
Lanolin
– preservative and chelating agent (remove calcium)
→ prevent Band Keratopathy
EDTA
chelating agent (remove calcium)
EDTA
Chemical Disinfecting Agents
- Hydrogen Peroxide - H202
- Chlorhexidine and Thimerosal
- Alkyltriethanol Ammonium Chloride (ATEAC) and Thimerosal
- Dymed
- Polyquad
- Povidone Iodine
- Hexachlorophene
