Contact Lens Fitting
When patients prefer contact lenses instead of eyeglasses, additional evaluation is typically required to find the right type and size of contact lens. This additional evaluation is commonly referred to as a "contact lens fitting." Most providers charge an additional fee for this type of fitting and the fee will vary depending on the provider. The cost may also vary due to circumstances or complexities involving condition of the eyes and cornea, the lens prescription and the type of lenses used.
The first step in contact lens fitting involves measuring the patient's eye to determine the correct size of the contact lens. In the case of disposable contact lenses, "trial" lenses may be issued so that the fit can be evaluated. Patients new to contact lens wear will be instructed on proper cleaning, insertion and removal of the lenses. A wear schedule may be prescribed to allow the patient to adapt gradually to the lenses, leaving them in for longer periods each day. The Doctor may carefully monitor the eyes over a specified period of time to determine a proper fit and to ensure that there are no complications.
There are generally two categories of contact lens patients: (1) Elective/Cosmetic and (2) Medically Necessary.
Most contact lens wearers fall under the "elective/cosmetic" category. These patients have chosen to wear contact lenses for cosmetic, fashion or vocational reasons.
Some patients cannot achieve clear, comfortable vision with eyeglasses due to certain medical conditions. Medical conditions that may make these lenses necessary include: Keratoconus, Anisometropia, Aphakia and Pseudophakia. (Prior Approval is required to authorize medically necessary contact lenses).
Types of Prescription Contact Lenses
Contact lenses have been traditionally categorized by their material type: being either "Soft", "Rigid Gas Permeable (RGP)" or "Hard" lenses ("Hard" lenses are virtually obsolete and rarely used). In addition to being categorized by material, contact lenses may also be identified by their wearing characteristics (daily-wear, disposable, planned replacement, etc.) and according to the type of prescription (toric, bifocal, monovision etc.). The following terms are generally used in describing the various types of contact lenses.
"Daily-wear" soft contact lenses
These lenses are made of flexible, soft plastics that allow oxygen to pass through to the eye. They are easy to adjust to and comfortable to wear. Because they fit close to the eye and are difficult to dislodge, they are often recommended for sports. They won't correct all vision problems, however, and may not provide the sharp vision required by some wearers. They also require daily removal and cleaning.
Disposable soft lenses are normally worn for one or two weeks and then discarded. They are easy to adjust to and comfortable to wear. Because they fit close to the eye and are more difficult to dislodge, they, too, are often recommended for sports. As with the "daily-wear" lenses, they won't correct all vision problems and may not provide the level of vision required by some wearers. They also require daily removal and cleaning, but need much less maintenance than standard daily-wear soft contact lenses.
This type of disposable lens is designed to be worn for a single day, discarded at night, and replaced by a new pair in the morning. The big advantages are that no lens care is needed and a fresh pair of lenses is worn every day.
These contact lenses are replaced on a planned schedule, usually monthly or quarterly. They are available for most prescriptions and require less care than standard daily-wear contact lenses, since they are frequently replaced.
These contact lenses can usually be worn for a specified number of days (overnight) without removal. Because of the "extended" wear time, more frequent visits to the eye doctor for follow-up care may be required. "Continuous wear" is a term that's sometimes used to describe 30 consecutive nights of extended lens wear - the maximum wearing time approved by the FDA.
Gas permeable (RGP) contact lenses
RGP contact lenses are manufactured from slightly flexible plastics that allow oxygen to pass through. These lenses may provide sharper vision than standard soft lenses and can be used to correct most vision problems. They are also more durable and easier to care for, but often require a considerably longer period of adjustment.
Contact lenses that contain both a spherical and cylinder component to correct prescriptions in patients who have astigmatism. These lenses may be thicker in one area than another to maintain correct orientation on the eye.
As with multifocal eyeglasses, bifocal contact lenses are designed to provide sharp vision up close and at a distance. Various designs are available depending on the specific needs and adaptability of the patient.
Monovision is a contact lens fitting technique that is an alternative to bifocal contacts. Using this technique, the eye doctor fits a close-up prescription contact in one eye for reading and a distance vision contact in the other. The technique can be very effective for some patients, but requires some adaptation and sometimes results in compromised depth perception. Monovision fitting can be performed with virtually any type of standard or specialty contact lens.
Hybrid contact lenses
Hybrid contacts are large-diameter lenses that have a rigid gas permeable central zone, surrounded by a peripheral zone made of soft or silicone hydrogel material. The purpose of this design is to provide the visual clarity of GP lenses, combined with wearing comfort that is comparable to soft lenses.
Hybrid contacts for keratoconus have a special design that enables the central GP zone of the lens to vault over the irregularly shaped cornea. Hybrid lenses also are available for the correction of nearsightedness, farsightedness and astigmatism in healthy eyes.
Soft contacts for keratoconus
Today there are even custom soft contact lenses that can correct mild to moderate keratoconus. These special, made-to-order soft lenses sometimes are more comfortable than gas permeable or hybrid contact lenses for people with keratoconus or irregular corneas.
Custom soft contacts for keratoconus typically have a larger diameter than regular soft lenses and have either a medium or high water content. Examples include KeraSoft IC lenses (Bausch + Lomb) and NovaKone contact lenses (Alden Optical).
Sometimes custom soft lenses are recommended for people with keratoconus who enjoy excellent vision with GP or scleral lenses but cannot wear rigid lenses comfortably all day. For example, custom soft lenses might be worn for leisure activities during the day, and GP or scleral lenses might be worn for night driving and other activities that demand sharper vision.