contact lens primer
Soft Contact Lenses Why Fit 'Em?
BY TIMOTHY B. EDRINGTON, OD, MS, FAAO, & JOSEPH T. BARR, OD, MS, FAAO
Initial comfort and instant gratification! OK, there are other compelling reasons to prescribe soft contact lenses. Initial comfort with soft contact lenses is due to their large overall diameter (minimizing lid interaction), thin edge designs,
(minimizing lid interaction), thin edge designs, limited movement, resulting from flexibility of the materials (low modulus of elasticity) and decreased surface resistance (they're wet). Other advantages of soft contact lenses, when compared to rigid lenses, are faster adaptation (making them an excellent choice for part-time wear), no spectacle blur (corneal swelling tends not to be localized), excellent for sports (less apt to dislodge), and they may be prescribed for therapeutic purposes such as recurrent corneal erosions. Cosmetic and prosthetic tints appear more natural and don't move excessively with blinking, thereby avoiding an unattractive diversion.
Poor soft lens candidates include patients who suffer from extreme dry eyes or who are exposed to chemicals or fumes. Patients requiring extremely crisp vision or who have corneal distortion due to disease, trauma or long-term lens wear tend to obtain better vision with RGPs.
Soft Lens Advancements
Increased frequency of lens replacement has revolutionized the way eyecare practitioners manage their contact lens patients. In the past, many soft lens patients exhibited sensitivity to their care solutions or suffered from giant papillary conjunctivitis (GPC) induced by heavy protein deposits on their lenses. These patients now benefit from the availability of more frequent replacement lens options and improved lens care systems.
Other segments of the soft contact lens market have also grown. Toric lenses are now more reproducible, increasing practitioner and patient confidence in the success of this design. More lens replacement options (including two-week replacement) are now available, and manufacturers are more generous in their exchange policies. Parameter availability has also increased, allowing more patients to be prescribed soft torics.
New options in bifocal soft contact lenses appeared on the scene. Disposable bifocals allow the patient and practitioner a more financially "risk-free" program to assess the lenses. Dispensing from a liberal trial lens set gives immediate feedback and allows for more efficiency in fine-tuning the prescription.
Tinted soft contact lenses have been popular in many practices. Success with tinted lenses is largely dependent on the practitioner's willingness to enthusiastically offer this option to patients.
Patient surveys continue to inform us that they have an interest in "safe" extended wear. Bausch & Lomb recently introduced a high Dk (110) soft silicone-hydrogel lens that is FDA approved for seven-day continuous wear.
Daily disposables have provided us with more opportunities to prescribe contact lenses to meet the needs of our patients' varying lifestyles. Many patients prefer only occasional wear of contact lenses, such as to play tennis or for social functions. A growing number of full-time contact lens patients prefer daily disposables for their convenience and comfort.
Yes, there are definitely more (and improved) soft lens options for our prescribing toolbox. Professor Otto Wichterle, inventor of the soft contact lens, would be proud.
However, it is important not to oversell either the benefits or disadvantages of soft versus rigid lenses. Don't burn your bridges, and keep the patient's options open.
Dr. Edrington is a professor and chief of contact lens services at the Southern California College of Optometry. E-mail him at email@example.com.
Dr. Barr is editor of Contact Lens Spectrum and assistant dean of students at The Ohio State University.