Planned Replacement for this Century
Older contact lenses have done a great job, but newer lenses have more to offer.
BY MILTON HOM, O.D., F.A.A.O., AND LORETTA SZCZOTKA, O.D., M.S., F.A.A.O.

Approximately 80 million people currently use contact lenses and this number continues to grow worldwide because the industry has been responsive to the needs of patients and practitioners. The original contact lenses were prescribed for conventional wear, but since then patients have been afforded the option of planned replacement and daily disposability.

At the beginning of the 21st century, 90% of contact lens wearers wore soft lenses, 43% of wearers wore disposable contact lenses, 21% wore frequent replacement lenses and 36% wore conventional wear lenses. About 10% of wearers wore gas permeable contact lenses.⁷

Many manufacturers compete with variations on planned replacement. Before blister packs became commercially available, some fitters were dispensing their own planned replacement programs with vialed lenses for extended wear.⁶

Possible complications of contact lens wear. At left, contact lens stromal infiltrate. At right, giant papillary conjunctivitis (GPC).These complications are reduced with the use of frequent replacement or disposable lenses.

The concept of frequent replacement has caught on because of its many advantages (See Tables 1 and 2). Trial lenses were provided to the doctors at minimal or no charge and in the beginning, doctors marketed these lenses to patients as free trial pairs. The fitter bought only the multi-packs and sold them to the patient. Practitioners could either stock lenses as inventory or order them as needed, but multi-packs offered the ultimate in convenience. To this day, some doctors feel that multi-packs have contributed to the trivialization of contact lenses. Initially, disposable lenses were intended for extended wear but they later emerged as the first choice for daily wear.⁶ Below are some reasons why.

MAKING THINGS EASIER

Convenience is the major reason behind the wide acceptance of disposable or planned replacement contact lenses by patients. With the advent of disposable lenses, lens care was simplified. They're also convenient for practitioners because multi-packs reduce the bother for a lost, torn or damaged lens. Most practitioners will replace damaged lenses at no charge from their trial lens supply.⁶

WEIGHING COSTS

Disposable and frequent replacement contact lenses have been marketed as being more economical than conventional contact lenses. Interestingly, the multi-packs alone have a higher cost than conventional lenses. However, the savings were realized by the need for fewer lens care products and cleaners for these lenses than for others.

TECHNICALLY SPEAKING

The FDA defines a disposable contact lens as a lens that the patient uses only once and throws away after removing it from his eye. If the patient reuses the lenses after disinfection, then the lens is technically defined as a planned or frequent replacement modality.⁶

Most practitioners identify a disposable lens by its wearing cycle. Lenses that are replaced after 14 days or less are disposable. Those replaced in one- to six-month intervals are defined as planned or frequent replacement. Conventional lenses are also referred to as reusable lenses.⁷

PLANNED REPLACEMENT

From a clinical standpoint, the thinking behind planned replacement contact lenses is simple: cleaner contact lenses produce fewer complications and problems.¹ Over time, all soft contact lenses suffer from spoilage and deposits. This is a fact of life when dealing with contact lenses. Using solutions and protein removers to clean lenses can slow down the process of spoilage and deposit accumulation, but replacing them before this occurs is best.

Prevention is usually better than a cure. How contact lenses feel to a patient can tell us when he needs to replace them. If the patient says that the new contact lenses feel considerably better than his older lenses, then it's probably too late and you should instruct the patient to change the new pair and future pairs of contact lenses earlier than he changed his last pair of lenses.

THE STANDARD OF LENS CARE

Shorter replacement cycles have raised the standards of lens care. The advent of shorter cycles has provided patients with simplified lens care. When patients mainly used conventional contact lenses, the care systems were designed to prolong lens life. Prolongation of lens life by reduction of deposits required superior cleaning action. More recently, frequent replacement and disposable lenses have given the solution manufacturers more leeway and have greatly enhanced innovation. In fact, most patients do well maintaining their lenses with one bottle and without the inconvenience of rubbing.

In the past, care systems followed many steps and required many solutions. We were accustomed to using a surfactant for digital cleaning, a saline rinse and an overnight soak. Sometimes the soak cycle required neutralization, as in the case of peroxide systems. Once a week, a "weekly cleaner" or enzyme cleaning was needed. After the enzyme cleaning, an additional disinfection cycle was needed. Patients would complain about the complexity of cleaning while toting around many bottles.

The care systems of today show extremely high acceptability and can even enhance wearing comfort. New ingredients have been added to multi-purpose solutions to make lens wear better. Almost all of the multi-purpose solutions of today have comfort-enhancing ingredients. Frequent replacement has "unshackled" the care systems.

SINGLE-USE LENSES

Daily replacement is the ultimate modality. It seems logical to replace contact lenses as often as possible. If cost and parameter availability weren't issues, then we could argue that all daily wear soft lens patients should use single-use lenses.¹

Daily disposable wearers have fewer symptoms, fewer deposits, better vision, fewer tarsal abnormalities, fewer complications and better overall satisfaction than patients who use conventional contact lenses.² Other studies have shown a significant improvement with lens comfort, dryness, soreness, scratchiness and vision with single-use lenses over previous planned replacement modalities.³ Complication rates are 4.9% for daily disposables and 8.5% for conventional daily wear soft lenses.⁴ Studies have also shown better convenience and comfort of single-use contact lenses over two-week contact lenses.⁵

Some of the complications that are reduced with frequent replacement or with disposable lenses are giant papillary conjunctivitis (GPC), corneal infiltrates, peripheral ulcers and microbial keratitis (See images).

Advantages of daily disposables include less chair time required for problems related to lens care systems and minimized patient anxieties about lost or damaged lenses. Whereas planned replacement has encouraged improvements in lens care, daily disposables have all but eliminated the need for solutions. Other advantages of daily disposables are fewer "disputes" about wearing cycles.

MONOVISION ADVANTAGE

One area where daily disposable contact lenses are especially valuable for their use in monovision. Daily disposable lenses are helpful during the trial lens fitting period.

Many times, just 0.25D of power change can make a huge difference to the patient. Disposable lenses allow much more accurate prescriptions with trial lenses. It's usually possible to undertake a trial on a monovision patient with the proper power and base curve. You can change contact lens parameters easily.⁸

Another area where daily disposable lenses are helpful is the greater flexibility. Patients can change modalities easily. Depending on need, a patient can change from monovision to two distance lenses.

For instance, monovision may be suitable for the patient to wear at work, but changing the near lens to a distance contact lens may make the drive home during the dark evening hours much safer.⁸

Contact lens stromal infiltrate.	Contact lens ulcer

COMPLIANCE ISSUES

Many of the advantages of daily disposable contact lenses are centered around the issue of fewer compliance problems. One major advantage of disposable and planned replacement contact lens modalities is that you can link the follow-up visits or annual exams to when the patient runs out of his supply of contact lenses. Although the lenses have reduced difficulties, practitioners may need to be more vigilant in certain areas.

A potential compliance disadvantage is the adoption of unwise contact lens care practices (ex. storing a lens over night in tap water), or reusing contact lenses after only a few hours of wear each day.

Additionally, because of the low unit cost of the lenses, patients may think that it's okay to allow friends to try on their contact lenses.⁸ So while daily disposable lenses offer many great advantages over other lens modalities, you still have to educate patients on the importance of compliance and caring for their contact lenses.

REFERENCES

1. Tanner Joe. Planned soft lens replacement. In: N. Efron (ed). Contact Lens Practice. Oxford: Butterworth-Heinemann. 2002.

2. Soloman O. Freeman M. Boshnik E. et. al. A 3 year prospective study of the clinical performance of daily disposable contact lenses compared with frequent replacement, and conventional daily wear contact lenses. CLAO Journal. 22: 250-257.

3. Jones L. Jones D. Langley C. et. al. Subjective responses of 100 consecutive patients to daily disposables. Optician 199(5240):15-23.

4. Hamano H. Watanabe K. Hamano T. et. al. A study of complications induced by conventional and disposable contact lenses. CLAO Journal. 20:103-108.

5. Sindt C. Daily disposable versus two-week disposable lenses. CL Spectrum 14(5):33-38.

6. Gailmard NB. Gailmard SM. Frequent replacement and disposable lenses. In: C. Schwartz Specialty contact lenses: a fitter's guide. St. Louis: Elsevier Health. 1996;11:118-125.

7. Freeman MI. Disposable and frequent replacement contact lenses. In: HA Stein, BJ Slatt RM Stein. Et.al. Fitting guide for rigid and soft contact lenses a practical approach 4e. St. Louis: Elsevier Health. 2002;32: 411-418.

8. Efron N. Contact lenses A-Z. Oxford: Elsevier Health. 2002.