RGP insights

The Comeback of the Piggyback

BY LORETTA B. SZCZOTKA, OD, MS
DECEMBER 1999

Piggyback contact lens fitting is often reserved for the most challenging cases, or only routinely implemented by a select group of contact lens practitioners. Recently, the piggyback fitting technique has been revisited. Paragon Vision Sciences has been heavily promoting their Flexlens PiggyBack soft contact lens, which incorporates an anterior cutout zone in which an RGP can be countersunk for improved centration. Additionally, investigators from The Ohio State University and The CLEK Study have just completed the largest pilot study of the feasibility of fitting keratoconic patients with piggyback lenses.

Piggyback fitting is most often used to solve comfort problems in keratoconic patients and to manage recurrent abrasions.

Piggybacking Pearls

When RGP intolerance and discomfort persists in first-time wearers, try adding a piggyback soft lens to act as a wedge between the RGP and the cornea during the adaptation phase. Although lid sensation of the RGP will continue, the patient's lessened awareness of the RGP on the cornea will encourage him to continue lens adaptation. Usually steep (base curve <8.5mm) daily or two-week disposable lenses work best for moderate to advanced keratoconic patients. Often, only a three-month supply is required to gradually discontinue use of the soft lens either due to RGP acceptance or frustration with handling four lenses on a daily basis! Try using piggyback fitting to aid patients who depend on their lenses in the evening hours. If the fit is successful, the patient can gain six or more hours of wearing time a day.

Recurrent abrasions induced by an RGP over a compromised area of corneal epithelium can benefit from intermittent or permanent use of a piggyback system. Areas prone to breakdown include the cone apex, raised scars covered with hypertrophied epithelium and proud nebula.

If a successful clearance RGP fit can't be achieved to prevent mechanical impingement over the fragile zone, then piggyback fitting is indicated. Some patients can detect the early signs of an impending abrasion, and temporarily use the soft lens when their first symptoms present. Education is critical for such patients to prevent inappropriate use of the soft lens, which can delay the treatment of more severe complications.

Sagging cones and tight lids often cause persistent RGP lens decentration that cannot be counteracted with traditional refitting techniques. If a thin disposable lens still fails to improve centration, the Flexlens PiggyBack is an excellent alternative. Order the RGP diameter about 1mm smaller than the anterior cutout in the soft lens for the best performance, and remember to use high molecular weight fluorescein to evaluate the fit. My most successful fits are those which have a three-point-touch pattern over the soft lens carrier, with an adequate but narrow peripheral edge lift to ensure entrapment of the RGP within the anterior cutout.

Although hypoxia has been a major concern with fitting full-time piggyback lens wear, hyper-Dk RGP and silicone-hydrogel lenses can now be incorporated into the piggyback system to improve transmissibility.

Dr. Szczotka is an assistant professor at Case Western Reserve University Dept. of Ophthalmology and Director of the Contact Lens Service at University Hospitals of Cleveland.