Contact Lenses

English: Color contact lens on eye(chocola color) 日本語: カラーコンタクトレンズ装用例（ショコラ色のレンズ） (Photo credit: Wikipedia)

Contact lenses are very useful and are the most appropriate alternative method for eyeglasses. The first contact lens was made in 1880 from glass material and the first contact lens solution was created by a pharmacist called Dr. Harry William Hind in 1940. These days contact lenses are worn by “Approximately 36 Million Americans…”( http://www.clspectrum.com/article.aspx?article=12913) Contact lenses differ between people it depends on one’s eyesight and how affected they are.

Properties and Ingredients

The primary ingredient in contact solution is Hydrogen Peroxide and there are other several chemical ingredients as well such as Benzyl Alcohol, Edate Disodium, Polyaminopropyl Biguanide and Chlorhexidine Gluconate. These other ingredients help to get rid of bacteria that may have started to form or to remove heavy metals and calcium from the blood. Chemical formula for hydrogen peroxide: H2O2 H+1 + HO2-1
Equilibrium has to occur in the acidity level, tonicity, buffering agents and viscosity so the contact solution can replenish the lens.
The pH value of the liquid layer that covers the cornea has acidity level anywhere around 7.0 to 8.5. Meaning that the contact lens solution should have pH around those two levels so no irritation or discomfort is felt to the eye. Contact Lens solution has a high buffering capacity which resists pH level changes. Which results in a equilibrium between the eye and the lens.
Buffering agents are used to stabilize the pH level between 7.4 and 7.0. Common buffering agents are Trimethamines, borates, phosphates and citrates.
Finally tonicity of the solution which depends on the amount of salt is in the solution. Ideal contact lens solution has almost one percent of sodium chloride. This means that equilibrium has to be maintained if by chance the concentration of other salts decreased the concentration of sodium chloride would have to increase vice/versa. The contact lens has been made isotonic meaning that they have the same osmotic pressure as the tear film in our eye (the liquid that protects the cornea). Therefore equilibrium is needed between ocular tissue and the water lens so no swelling occurs.
Society
Contact lens solution tries to protect your contact lenses but it doesn’t ensure 100% safety. There have been numerous bacterial infections in the eye because of contaminated hands touching the cornea. Therefore some people where glasses so no chance of harm can occur to our eyes. Old is Gold! There is a student that attends Fletcher s Meadow who has to wear glass temporary because he got eye infection due to touching his eye with contaminated hands.

Work cited
Richard, Cicely A.. “What Are the Ingredients of Contact Solution? | eHow.com.” eHow | How to Videos, Articles & More – Discover the expert in you. | eHow.com. N.p., n.d. Web. 7 May 2013. .
“Pharmacist, Inventor Harry William Hind Dies « Colleagues « Healthcare Jobs, Information, Conferences.” Healthcare Jobs, Information, Conferences. N.p., n.d. Web. 7 May 2013.