A Judicious Approach to
RGP Planned Replacement

BY EDWARD S. BENNET, O.D., M.D.. ED.
AUG. 1997

The RGP question of the hour seems to be: Should I prescribe planned replacement for RGPs? Because high Dk materials (>50), particularly the superpermeables (>90), are more prone to surface contamination and scratches, a planned replacement schedule seems appropriate. And it follows that patients who benefit from high Dk materials -- hyperopes, people who want flexible and extended wear, and those with hypoxic problems, traumatized corneas, neovascularization or diabetes -- are all potential candidates.

People with very active lifestyles who don't want to be inconvenienced by waiting for a replacement lens, and patients who frequently lose or break lenses are also good candidates for planned replacement.

IN SUPPORT OF MORE FREQUENT REPLACEMENT

In a retrospective study, Jones et al. (1996) found that <40 Dk lenses should be replaced about every 20 months; 41-89 Dk lenses every 16 months; and >90 Dk lenses every nine months, usually due to surface deposition, breakage and warpage. This was confirmed by Michel Guillon (1996) who reported on five superpermeable materials and found that the length of time lens performance remained unchanged was highly patient-dependent, but in most cases was less than six months.

Woods and Efron (1996) reported that individuals who replaced their superpermeable lenses every three months showed significantly less lens adherence, mucous coating and corneal staining than those who replaced their lenses as needed.

The convenience of always having a spare pair of contact lenses cannot be emphasized enough. This should also decrease the incidence of emergency phone calls to replace a lost or broken lens.

BUT IS RGP PR FOR EVERYONE?

Right now, it appears that the answer is no. The best-known benefits of RGP lenses are their durability and longevity. If a lens is still good, why replace it? This is particularly true with low Dk materials, which can last up to two years. Although manufacturing quality is improving, patient dissatisfaction with a replacement lens is still possible.

Also, I don't necessarily agree that dry eye patients are good candidates for RGP planned replacement, at least not until the material technology is such that lipid and mucus-based surface contamination for the superpermeables is no greater than that with lower Dk materials.

The rationale that lens care is less complicated with RGP planned replacement is not necessarily true. Surfactant cleaning is important regardless of the replacement schedule, and the new liquid enzymes make it much simpler for all lenses.

The final concern is a legitimate one. Will RGP lenses that are replaced more frequently be perceived similarly to soft lenses? According to Jon Kendall, O.D., as planned replacement has become the trend in soft lenses, there are fewer new polymers, fewer parameters and more discontinued lens brands. Most important, patients perceive soft lenses as a commodity, not a medical device. People who wear RGPs have a greater appreciation of the custom nature of their correction device and tend to be more loyal to the prescribing practitioner. Whether this will be an issue for patients on a relatively infrequent replacement schedule remains to be seen.

THE BOTTOM LINE

For certain materials, a six-month or even one-year planned replacement program makes sense, especially if the laboratory discounts the additional lenses. Some manufacturers have introduced their own planned replacement programs and offer practice support materials.

RGP planned replacement could mean providing two pairs of lenses initially with a six-month evaluation required or providing one pair and holding the second pair until the six-month visit or as needed. Obviously, there are benefits to an RGP planned replacement program, but is it for everyone? Not yet. CLS