Rigid Gas Permeable (RGP) contact lenses are frequently prescribed to correct vision in keratoconus-afflicted adolescents and adults. Yet, these lenses can be too uncomfortable in people with persistent corneal pain for all-day use. Since the Covid-19 pandemic has resulted in many people working from home or attending classes via videoconferencing software, having adequate vision to interact online with employers or teachers has become necessary. A research article in Eye and Contact Lens in 2017 noted that Piggy-Back (PB) contact lens systems were first used in keratoconus-afflicted people who were unable to comfortably tolerate Rigid Gas Permeable contact lenses in their eyes. The following describes Piggy-Back contact lenses.
What are Piggy-Back Contact Lenses and Why Were They Developed?
There is no single lens that is a “Piggy-Back” lens, but this term refers instead to a system in which a Rigid Gas Permeable lens is placed on top of a soft contact lens. According to the National Organization for Rare Diseases (NORD), some people with keratoconus are unable to comfortably-wear contact lenses that rest on the cornea (such as Rigid Gas Permeable and “Piggy-Back” lenses) due to progressive corneal thinning, corneal ulcers, and/or corneal pain.
However – since traditional soft contact lenses do not correct for astigmatism (as typical in keratoconus) – Rigid Gas Permeable contact lenses remain the foremost contact lenses prescribed for a person diagnosed with both myopia and astigmatism. (Scleral contact lenses in the past decade have been prescribed at increasing rates for keratoconus-afflicted people with astigmatism and corneal pain, but correct insertion involves a steeper learning curve.)
According to the National Keratoconus Foundation (NKF) the soft lenses utilized in Piggy-Back contact lenses can provide cushioning for people who are intolerant of their Rigid Gas Permeable contact lenses (i.e., feeling that their RGP lenses are foreign bodies in their eyes). Furthermore, the NKF notes that keratoconus-afflicted people with decentered cones may find Piggy-Back lenses work better for them than solely RGP contact lenses.
Piggy-Back lenses were developed to enable children with both myopia and astigmatism to comfortably-wear contact lenses to improve eyesight, as well as provide another corrective eyewear option for anyone unable to benefit from other available corrective lenses. A disadvantage of Piggy-Back contact lenses is that two contact lenses need to be utilized in each eye, as well as the proper utilization of two different cleaning solutions.
Hybrid Contact Lenses and Scleral Contact Lenses
Other options for keratoconus-afflicted people who cannot tolerate Rigid Gas Permeable lenses are hybrid lenses and scleral lenses. The NKF describes hybrid contact lenses as having a Rigid Gas Permeable center surrounded by a soft border. Meanwhile, scleral contact lenses do not rest on the cornea, so may be a better option for keratoconus-afflicted people with cornea pain. In addition, scleral lenses are recommended for keratoconus-afflicted people with “dry eye” syndrome since these lenses include a fluid-filled reservoir.
Corneal Infections and Contact Lens Care
An infection in the cornea can both permanently damage the cornea and worsen vision in people with keratoconus – and incorrect contact lens care can easily lead to infection. Therefore, correct cleaning and storage of contact lenses is essential. Inserting contacts with unwashed hands can introduce pathogens (such as Staph. aureus) into the eye. Since children and adolescents may disregard proper hand hygiene due to a lack of understanding the potential negative ramifications, parents need to emphasize the importance of hand-washing before any occurrence of contact lens insertion or removal.
The professionals at the Precision Keratoconus Center can assist you in determining the type of corrective eyewear that is appropriate for your needs.