Contact Lenses Care

I am short sight patient, I never asked questions about my glasses or contact lenses (normally I directly went to my doctor). Until I had to shop my own lenses some years later, so I started to wonder this question: Why Two Systems of lenses?

In hard lenses and gas-permeable lenses, wetting solutions are a most important product. They are directly responsible for making the lenses more comfortable. Hard lenses have a slick, hydrophobic (water-hating) surface over which water and tears do not readily spread. Wetting solutions make the lens’s hydrophobic surface a hydrophilic (water-loving) one that accepts water more readily. Wetting solutions must, however, be applied to a clean lens to be effective. So there must be a cleaning solution to remove the deposits and dirt that can accumulate during wear. A soaking and storage solution is also needed to keep the lens clean and aseptic when not being worn. Thus for hard lenses you use a system of daily cleaning, wetting, and soaking solutions.

By contrast, another problem takes precedence in soft lenses and extended-wear lenses. These are made of naturally hydrophilic plastics that are almost spongelike in their ability to absorb water. Unlike hard-lens polymers, soft lenses may also absorb other substances; thus, keeping them clean is a major priority. The traditional preservatives used in hard contact lenses will bind chemically with the soft lenses, causing damage to the lens and irritation to the eye. In addition, wetting solutions aren’t necessary; however, a different procedure, disinfection, is needed. Hence soft lenses require a special system and different solutions. A daily cleaning, rinsing, and disinfection /storage system is used, along with a weekly special cleaning with an enzyme solution.

For both types of lenses there are additional lubricating products that rewet, clean, and cushion the lenses while they are worn.

Hard lens solutions should never be substituted for soft lens solutions, and vice versa! Look carefully when you buy to make certain that you get the correct solution for the specific lens.

Contact Lens Solution Ingredients

The list of exotic chemical names on the packaging is a long and puzzling one for most contact lens wearers. Here are the most important common ingredients and what they do.

Buffers. Used to adjust and prevent changes in the pH (acidity / alkalinity) of the solution to make it more compatible with the tears and the eye:

• Sodium bicarbonate Sodium phosphates Sodium borate
• Boric acid

Surfactants. Surface-active agents (detergents) that purify or cleanse:

• Octylphenoxy (oxyethylene) ethanol Polyoxyl 40 stearate
• Tyloxapol

Chelating Agents. Remove metallic ions in a solution and stabilize and enhance the effectiveness of other agents:

• EDTA
• Edetate disodium

Disinfectants and Preservatives. Destroy or inhibit the growth of microorganisms:

Benzalkonium chloride Chlorobutanol

• Thimerosal
• Phenylmercuric nitrate
• Chlorhexidine gluconate
• Sorbate (sorbic acid)

Wetting and/or Lubricating Agents.Cushion the lens against the eye and lubricate the lens:

• Octylphenoxy (oxyethylene) ethanol Providone
• Polyvinyl alcohol
• Hydroxyethyl cellulose
• Polyethylene glycol 300

In addition, soft lens wearers use an enzyme cleaner containing proteolytic pa pain, which digests protein deposited on the lenses by tears and lid secretions.

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