A 49-year-old keratoconus patient complained of decreased vision in both eyes for six months. The patient had been successfully fit by another practitioner with corneal lenses, with her left (R)GP piggybacked on a daily disposable soft lens (Figure 1). She reported using Optimum (Lobob) for cleaning and disinfecting her (R)GP lenses. Systemically, the patient has been a Type II diabetic for the previous nine years with a recent hemoglobin A1C reading of 12% (for people without diabetes, the normal range for the hemoglobin A1C test is between 4% and 6%).
Visual acuity with her contact lenses was 20/100 and 20/200 in the right and left eyes respectively, but was correctable to 20/40 and 20/30 with over-refraction. The right (R)GP lens had a lid attachment fit without any excessive lens bearing. The daily disposable soft lens (nelfilcon 69%) of the left eye showed adequate centration and movement. The piggybacked (R)GP of the left eye demonstrated complete corneal vault and adequate centration, but did eventually drop mildly between blinks. Several sets of (R)GP lenses duplicating the fitting parameters but adjusting the power to accommodate her fluctuating refractive error were dispensed to the patient while her diabetes was uncontrolled. At her last contact lens check, her vision measured 20/20 OD and 20/30 OS. Her left eye did improve to 20/20 with an S-0.50D over-refraction. The patient also reported that more recently she achieved a 7.2 A1C reading.
Although this case highlights the importance of diabetes control to prevent refractive fluctuations, it also highlights using a daily disposable soft contact lens for a piggyback system, which has a number of advantages over a planned replacement soft lens design. First, the complexity of wearing two lenses in each eye is lessened by the fact that no additional care is needed for the soft lens. Secondly, lens deposits and allergen buildup are not factors that will interrupt the contact lens system. Keep in mind that most (R)GP soaking solutions will react negatively with the soft lens and so using a hydrogen peroxide or alcohol-based cleaner is recommended for cleaning and disinfecting the (R)GP lens. Although the soft lens was a standard hydrogel, consider using a daily disposable silicone hydrogel if hypoxia is a concern.
Greg DeNaeyer is a 1998 graduate of The Ohio State University College of Optometry. He completed a hospital based residency at the Columbus VA Medical Center. Greg joined Arena Eye Surgeons in 1999 and is currently the Clinical Director. His primary interest is specialty contact lenses.
Greg is the president of the Scleral Lens Education Society and is a Fellow of the American Academy of Optometry. He is a contributing editor for Contact Lens Spectrum and a contributor to Review of Cornea and Contact Lenses and Optometric Management. Currently his primary research is focused on profilometer designed scleral contact lenses, scleral lenses that correct higher order aberrations, and topical drug delivery devices. He has consulted for Visionary Optics, Essilor, Inspire Pharmaceuticals, B+L, and Aciont.