Contact Lenses Specialty Lenses

By Scott Burge, OD

Maryland Eye Associates

. http://marylandeyeassociates.com

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Contact Lenses Specialty Lenses

There are a wide variety of contact lens cases that are both challenging and rewarding. Beyond the commonly used soft lens products, which the large majority of contact lens patients enjoy, there are advanced designs and materials to address special cases.

Children, adolescents and young adults with myopia (nearsighted) from -1.00 to -3.00 have the option of being fit with CRT Rigid Gas Permeable lenses for the purpose of reshaping the cornea to eliminate the need for wearing glasses and contacts during the day. This lens is a specialized “reverse geometry” design that is worn during sleep, typically every night, and removed upon awakening. Wearing the lens flattens corneal curvature. The myopic measurement is neutralized and the patient has 20/20 vision all waking hours.

This result is similar to that of LASIK surgery, however, with CRT lens wear there is no surgery. If lens use is discontinued, the cornea returns to its pre-lens wear state in a week or two. While not a medically validated outcome, patients who wear CRT RGP lenses usually do not have a progressive myopic increase over time.

Eye doctors who fit these lenses have to be well experienced in working with rigid gas permeable lenses and committed to monitoring corneal integrity, lens fit and patient compliance to assure success.

Patients with high refractive measurements, including astigmatism, have several contact lens options. Soft astigmatism (toric) lenses are now available in extended power ranges for nearly all patient prescriptions. However, because the lens is floating on the cornea, lens rotation may cause misalignment of the sphere and cylinder power curves resulting in intermittent blurred vision. Some toric lens brands perform better than others. Diagnostic fitting and evaluation with trial lenses from different companies requires perseverance and patience.

There are two specialty contact lens alternatives when soft toric lenses are not providing consistent, clear vision Bitoric RGPs and Hybrids. Bitorics are double curve Rigid Gas Permeable lenses that accurately correspond to and optically neutralize the corneal curvatures that are causing astigmatism. Hybrid designs are a “combination lens” made with a RGP center and a peripheral soft lens skirt. SynergEyes Duette and Ultra Health are two leading brands in this category.

The goal of Hybrids is to provide the superior clarity of RGP lenses while improving comfort with the peripheral soft lens skirt. Both types of lenses require experience and expertise for successful fitting. Conditions appropriate for these designs include keratoconus, LASIK complications, irregular corneas and corneal transplant cases.

Not all cases that initially appear complex require specialty lenses. Sometimes a straightforward refit with a different brand lens solves the patient's problem. Sometimes an adjustment to the base curve, diameter and power will solve problems of centering, stability and clarity. It is the eye doctor's responsibility to identify the best options for patient success and satisfaction.