cleaning and disinfection
2 main components of care system of contacts
used to remove debris from the lens surface from the surface of the contact lens - clean immediately after lens is removed - often used in Hydrogen Peroxide-based systems.
a preservative primarily used as an antimicrobial agent and secondarily as a surfactant in GP lens disinfection system but not in soft lens disinfection system. It is responsible for killing microorganisms and inhibiting their future growth in RGP solutions.
are used in solution to keep them in the range of ph 6 to 8. Includes agents such as citrates, phosphates, borates, and trimethamines.
reduce the level of microbial contamination to a safe level
no rub solution
should still involve a digital rubbing of the lens surface
use for rinsing only. Does not disinfect lenses - made to resemble tear with 0.9 sodium chloride -ph between 7.0 to 7.4
Thermal (heat) and chemical
ways to disinfect soft lens.
-Can harden on deposits and often shortens the life of the lens
-Needs to be used in addition to surfactant cleaning.
- Is most effective against acanthamoeba cysts and trophozoites
occurs when all viable microbes are eliminated
use to clean and disinfect contact lens.
The preservatives in mutli-purpose solutions do not kill microorganisms, but prevent them from multiplying in the solution after the bottle has been opened.
used to remove accumulations of tear proteins, predominantly lysozyme, from the contact lens surface
- Should be used on RGP lenses at least once per week to remove deposits.
- Enzymatic cleaning of soft lenses is important because it prevents the development of Giant Papillary Conjunctivitis, it prevent the lens from shrinking and tightening, and it maintains the hydration of the lens
acts as lubricating drops
Mercury based preservative used in some cleaning solutions to aid in the prevention of bacteria growth in the solution. Less popular in recent years because some people have adverse reactions to it.
Hydrogen peroxide system
The most effective solution for removing deposits/all pathogens from soft contact lenses. They are more effective against viruses and fungi than most chemical disinfection systems. However, residual hydrogen peroxide from incorrectly disinfecting soft contact lenses can cause epithelial damage. In addition, the use of generic 3% hydrogen peroxide solutions can cause lens discoloration.
a preservative derived from the benzalkonium chloride. Used in soft contact lens solutions. It was first used for the storage solutions of contact lenses. Today it is found in many eye drops such as artificial tears and antiglaucomatous. It is considered less toxic to the corneo-conjunctival surface
propylene glycol and hydroxypropyl methylcellulose (HPMC)
used in multi-purpose solutions as wetting / comfort agents
Combination wetting/soaking solutions
are used with RGP lenses to maintain lens surface wettability, to disinfect the lens, and to cushion the lens during insertion.
It is a disinfectant and preservative for RGP and PMMA lens.
- It is unsuitable for use with soft contact lenses
- Benzyl Alcohol is non-cytogenic and relatively non-sensitizing
- It is bactericidal and viricidal but ineffective against Pseudomonas aeruginosa in low concentrations like other alcohols (isopropyl alcohol, isopropanol, ethanol), it behaves like a lipid solvent
has antibacterial and limited antifungal activity. Its concentration in soft contact lens solutions has not been shown to cause the death of the corneal epithelial cells. Sorbic Acid causes yellow or brown discoloration of the contact lens due to its interaction with Amino Acid (lysine) and tear protein.
It is a chlorinated alcohol preservative with a broad spectrum of action.
- It is slow-acting against and bacteria and has a distinctive odor.
- Chlorbutanol is effective in acidic pH and used along with other preservatives
The most common observable sign of this condition is mild conjunctival redness in both eyes which affects the exposed nasal and temporal quadrants as well as the upper and lower bulbar conjunctiva.