Contact Lens and the Cornea

Contact Lens and the Cornea

Cornea is a clear, remarkable biological tissue that sits in front of the eye.  It is one the few tissues of the human body that is devoid of blood vessels. It is the main part of the eye that is taken into consideration when fitting a contact lens.  Technology in contact lens have evolved greatly, materials allow more oxygen to  eyes for better comfort and range of options for correcting astigmatism to presbyopia (correcting for distance, near, and intermediate simultaneously).

Aside from soft contacts lens, there are contacts made from of durable plastic known as rigid permeable gas lenses (RGP lenses). The designs of these lenses are superior because they give good optics, better breathability, and fewer deposits adhere to them than soft lenses.  All of these properties make them ideal for patients that suffer from moderate to severe allergies and dry eye that cannot tolerate soft contacts.  In fact these lenses are medically necessary for patients that have diseases of cornea such as keratoconus, irregular astigmatism, and for patients who have undergone corneal surgery. Post-refractive surgery patients are at increased likelihood of dry eye and patients that undergone corneal surgeries have altered corneal geometry that prevents them from achieving optimal vision with spectacles.  RGP lens are ideal for these patients as they come in various sizes and multitude of designs. They also are great for presbyopic patients and patients with high astigmatism that are unhappy with their vision in soft contact lenses.

Contacts are very safe, however, they also come with responsibility, from American Optometric Association.

Rookie Mistakes Patients Make:

  1. Overstayed welcome. Studies have indicated around half of disposable and frequent replacement lens users wear lenses longer than their recommended schedule. What barometer do patients use to change their lenses? They wait until the lenses become bothersome. That’s like saying, ‘I’m going to wear my underwear until they start to bother me. Thomas Quinn, O.D., AOA Contact Lens and Cornea Section (CLCS) chair says. “No, you change them before they start to bother you.”
  1. Caught dirty-handed. The cleanest, daily disposable lenses are all for naught if wearers do not wash their hands before handling their lenses. Dr. Quinn recalled a teenage patient with daily disposable lenses who persistently would be treated for corneal infiltrative events (CIEs). He learned the teen’s hands were never washed before handling lenses.
  1. Damp digits. The flip side of the coin: Although most patients do think to wash their hands, sometimes they forget to dry their hands before handling contact lenses. Water can harbor harmful microorganisms that can be transferred onto the lens and subsequently onto the eye if wearers fail to dry their hands with a clean surface.
  1. No respect for the system. Not all contact lens care systems are created equal, in terms of disinfection, and chemical sensitivities and incompatibilities with lens materials. Patients might opt for a cheaper, generic solution as opposed to the care system specifically designed for their lenses. “The cheapest solution isn’t always the best solution,” Dr. Quinn says.
  1. A case of grimy cases. Proper contact lens care extends to storage cases, as well. The AOA recommends wearers replace lens cases at least every three months, and cases should be cleaned and disinfected periodically in between.
  1. Dozing dangers. And finally, people snoozing in contact lenses that are not designed to be slept in are at a five times higher risk of developing CIEs, according to some studies. Even extended wear lenses carry some risk of infection as compared to daily wear lenses.


by Dr. Dixita Patel, OD