Its important that contact lenses receive appropriate care to retain their shape & optical characteristics & for their safe use
products used in the care of contact lenses include :
A) CLEANING SOLUTIONS :
All contact lenses are liable to become contaminated with oil , protiens , salt , cosmotics & atmospheric pollutants .
these contaminants must be regularly removed by cleaning solutions to ensure maximum comfort , clear vision & durability of the lens
Hard lenses require daily cleaning with a solution containing a non ionic surfactant such as tween 80
Deposits on soft lenses tend to be more proteinaceous . In addition to the daily surfactant cleaning , they require a regular enzymatic cleaning with a silution containing a photolytic enzyme
As enzymes are unstable in solution, they are supplied in the form tablets to be dissolved in sterile water immediatly before use
Cleaning solution may be isotonic or hypertonic . The latter is often preferred since concentrated solutions of sodium chloride have mucolytic properties which aids in cleaning process
DISINFECTING SOLUTIONS
The insertion of a lens contaminated with micro-organisms into the eye have very serious concequences . Therefor, contact lenses must be effectively disinfected before insertion
Disinfection can be accomplished by : Chemicah disinfection , the lenses are soaced in a solution containing an antimicrobial agent such as benzalkonium chloride , thiomersal or chlorhexidine . However , certain patients may develop sensetivity reactions with these compounds ; therefore an alternative chemical disinfection using hydrogen peroxide has been developed
To prevent eye irritation from residual hydrogen peroxide after disinfection , it is necessary that the lenses be exposed to one of three types of neutralizing agents ,
a catalytic type ( using catalase enzyme ) ,
a reactive type ( using sodium thiosulfate ) or
diluting type ( using sterile water)
SOAKING SOLUTIONS
Once the contact lenses are removed from the eye , they are placed in a soaking solution to maintain their hydration , curvature , diameter & optical characteristics.
Soaking solutions sre saline solutions which are isotonic with lachrymal fluid & of physiological pH .
They should contain anti-microbial preservative to protect the solution from contamination
For sensetive patients , preservative free saline solutions are also available & packaged in unit-dose vials or aerosol containers
D)WEETING SOLUTIONS
These are used to facilitate insertion of hard & gase permeablelenses & make them more comfortable to the patient
They provide temporary hydrophilic quantities to the hydrophobic surface of the lenses to facilitate their hydration by the tears
They also facilitate a cushion between the lens & the cornea
They cintain
a surfactant such as tween 80
a vicosity- inducing agent such as PVP ore hydroxyethyl cellulose
a presrvative such as benzalkonium chloride
& buffering agent
التعليقات
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