Piggybacks offer comfort, quality of vision
Keratoconus Tx seen as valuable option
Dr. Malooley added that when fitting piggyback lenses, it's best to ensure that the edge of the gas permeable lens is slightly flatter than it is in a non-piggyback application. "Err on the side of having a little bit flatter peripheral curve," she said. "If it's too tight it can bind down on the soft lens."
The two lenses should be stable but should be able to move independently of each other.
Dr. Faron advised to always use lenses with high Dk values when piggybacking. The higher the value the better it will transmit oxygen to the eye. "You really need the higher Dk because you have two lenses. If a patient is in a low-Dk RGP, it behooves the practitioner to upgrade him or her to a lens with a higher level of oxygen transferability when piggybacking."
Proper lens solutions
Drs. Faron and Malooley both noted that patients who are fitted for piggyback lenses must be educated about the importance of using the correct lens solution.
"You can use soft lens solutions on a gas permeable lens, but you can't use gas permeable solutions on a soft lens," Dr. Malooley said. "For our piggyback patients, we either have them use a soft lens solution for both lenses, or we have them use the hard solution for the hard lens, the soft solution for the soft lens, and then rinse both with the soft lens solution. Another option is to have patients use a hydrogen peroxide solution on both lenses, and then rinse them well with saline."
Don't be afraid to try piggybacking lenses, Dr. Faron said. "Get your feet wet and try it," he continued. "What we see on many keratoconus patients is that the apex of the cornea is much steeper than the RGP lens, and that leads to apical scarring and abrasions. These patients can really benefit from piggybacking because you want to get them back into a lens as quickly as possible, and you may not have time to fit them into a hybrid lens. So a good option is to simply slide a soft lens underneath a well-fit RGP and then follow them carefully to see how they do."
Although patients at first may be puzzled or even intimidated by the idea of adding a second lens, the immediate comfort they experience often sells them on piggybacks, Dr. Faron added.
"We see many patients who tell us, 'I was never told this existed,' or, 'No one ever tried this on me,' and we're not really doing anything unusual," Dr. Malooley said. "This is something that every optometrist can offer, if they so desire. Practitioners need to be encouraged to persevere and not be afraid to try things that might be a little outside of their comfort zone."
Chuck Faron, OD
Marsha M. Malooley, OD, FAAO
Drs. Faron and Malooley have no relevant disclosures.