Educational Content

 

Comprehensive Eye Care

 

More than you wanted to know about Contact Lenses!

  • Introduction
  • Basic Refreactive Errors
  • Bifocals and Multifocal
  • Lens Materials
  • Keratoconus
  • Tinted Contacts

Contact Lenses are NOT a simple commodity

Contact lenses come in many types. The tabs above will take you to specific information on this topic.

Contact lens prescription requires three steps: determination of the lens power, materials selection and then the actual determination of the fitting characteristics (shape and size) of the lenses to be prescribed.

You can understand that this process is more complex for new fits, or for refitting someone who is having problems. You can also understand that this is a different process form a Comprehensive Eye Exam.

Conditions correctible with Contact Lenses

A contact lens is designed to improve vision. Contact lenses can correct eye conditions including myopia, hyperopia, astigmatism, and presbyopia.

Myopia (nearsightedness)

A vision condition in which objects at near is clearer than objects that are far.

Hyperopia (farsightedness)

A vision condition in which objects that are far are clearer than objects that are near.

Astigmatism

Blurry vision caused by an irregular shape of the cornea or sometimes the curvature of the lens in the eye.

Presbyopia

The loss of the eyes’ ability to focus at near due to loss of elasticity of the crystalline lens. It usually occurs around age 45.

Keratoconus

Keratoconus is a condition in which the cornea has irregualr astigmatism, and generally myopia as well. Gas permeable contacts, sometimes in conjunction with soft materials, can give BETTER vision than eyeglasses for the keratoconic.

Presbyopic Contact Lenses: Multifocals

In our 40s, an eye condition called presbyopia develops, and we start having difficulty focusing on near objects. Today, a number of multifocal contact lens options are available. They provide less dependence on glasses, along with adequate distance and near vision.

Multifocal contact lenses come in both soft and rigid gas permeable lens materials. Some bifocal contact lenses have a design with two distinct lens powers, one for your distance and one for near. Some multifocal contact lenses act more like a progressive eyeglass lens, in which the power changes gradually from distance to near.

If bifocal or multifocal contact lenses aren’t as functional for you, the other alternative may be monovision or modified monovision. Monovision is where we use your dominant eye for distance and your non-dominant eye for reading. Sometimes we may try a modified monovision design, a combination of a multifocal in one eye and a single vision contact lens in the other eye.

Contact Lens Material

There are 2 basic type of contact lenses: soft and rigid.

Soft contact lenses:

Literally soft, pliable and comfortable, soft lenses are often categorized by their replacement schedule.  They come in a variety of hydrogel materials, including now silicone hydrogels. Daily disposables are disposed of each wear.  It’s the best for patients with ocular allergies, since it limits protein build-up.  They are also useful for patients who wear contacts infrequently or for sports activities like swimming.  More common are contact lenses that are disposed of on a two-week or monthly basis.  Advantages of a more frequently replaced contact lens include higher amount of oxygen to the eyes, less protein build-up, less prone to infection, and an easier cleaning system. Quarterly or annual lenses are not as common anymore but are useful for patients with higher prescriptions.

Rigid gas permeable (RGP) contact lenses:

Comfortable and thin, despite being rigid, these were derived from “hard” lenses. The original hard lenses did not allow oxygen to penetrate through the lens to the cornea, and they were often uncomfortable. Much improved in comfort, these new gas permeable lenses come in a variety of materials including silicone/acrylate, fluoro-slicone/acrylate, fluoropolymer, polystyrene, and silicone. They maintain their shape on the eye and don’t conform to the unequal contours of an astigmatic eye like soft lenses do.  When worn in the eye, the space between the back surface of the lens and the front surface of the cornea is filled with tears.  This layer of tears is shaped in a way that it becomes in effect a lens that corrects the astigmatism.  RGPs can provide crisper vision for patients with astigmatism, and they usually last a year or longer.

 

Hi-Tech keratoconic contact lenses

In patients with keratoconus, the cornea is cone-shaped and the surface is irregular resulting in a distorted image being projected onto the brain. As the cornea becomes more irregular in shape, it causes progressive nearsightedness and irregular astigmatism to develop, creating additional problems with distorted and blurred vision that cannot be corrected with glasses or soft contact lenses.

Treatment for moderate and advanced keratoconus include:

Rigid gas permeable: Patients with keratoconus see best with rigid gas permeable (RGPs) contact lenses. These lenses provide a clear surface in front of the cornea allowing the light rays to be projected clearly to the retina.  The rigid material enables the RGP to vault over the cornea, replacing its irregular shape with a smooth, uniform refracting surface to improve vision. There are a variety of types of specialized RGPs, and we will prescribe the one that is best suited for you.

Piggybacking: For those patients that have trouble with the comfort of a RGP lens, we can try a “piggybacking” contact lens method.  This method involves placing a soft contact lens over the eye and then fitting a RGP over the soft lens.  This approach increases wearer comfort because the soft lens acts like a cushioning pad under the RGP.

Hybrid: Hybrid contact lenses are a relatively new design that combines a highly oxygen-permeable rigid center with a soft peripheral “skirt”.  This has the potential to give good quality vision of a RGP with some comfort of a soft lens.

 

Tinted Contact Lenses

 

Visibility tints: These contact lenses are lightly tinted, so you can find your lens if you drop it. They do not affect the color of your eyes.

Enhancement tints: These colored contact lenses have a translucent tint that’s meant to enhance your natural eye color. They are slightly darker than a visibility tint.

Color tints: These colored contact lenses have a darker, opaque tint that changes the color of your eyes.

Light-filtering tint: These contact lenses are designed for athletes. They enhance certain colors and mute other colors to enhance performance.