Contact Lens Case Reports
Intolerance with a Scleral Lens
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO
When managing irregular astigmatism with rigid contact lenses, we have four primary modalities to consider: corneal lenses, piggyback lenses, hybrid lenses, and scleral lenses (Figure 1). Which modality will best serve a particular patient is complex and greatly influenced by the underlying ocular condition, the corneal and scleral topography, and practitioner experience and skill in fitting the various lens designs.
Figure 1. The four rigid lens options for managing irregular astigmatism.
This month’s case report involves a 68-year-old female with a longstanding history of bilateral keratoconus who underwent a corneal transplant, cataract extraction, and IOL implant to her right eye in the early 1990s. Since then, she has worn a wide range of different lens designs, including corneal lenses, piggyback lenses, hybrid lenses, and, most recently, scleral lenses.
A Surprising Scleral Result
In 2014, the patient was fitted with a scleral lens on her right eye that provided 20/25 vision; however, after numerous attempts with various lens brands and both symmetric and toric scleral designs, she failed to achieve adequate comfort with a scleral lens.
The inability of a patient to achieve comfort with a well-designed and well-fitted scleral lens is an uncommon and often unexplainable event. We believe that this intolerance may be based on a number of factors: 1) neurological hypersensitivity of the cornea, limbus, bulbar conjunctiva, or sclera to the presence of the lens; 2) a subclinical lens design issue related to the multiple junctions that are present on both the anterior and posterior surfaces of scleral lenses; and 3) subclinical anatomical anomalies in the toricity or asymmetry of the sclera.
Go with What’s Comfortable
This patient indicated that her best comfort had always been with the SynergEyes A (SynergEyes, Inc.) hybrid lens that she had worn approximately 10 years ago. The patient had been discontinued from this hybrid lens because the lower Dk of the soft skirt caused edema issues that resulted in significant peripheral neovascularization.
We refitted the patient with a SynergEyes Duette lens (Figures 2 and 3); these have an 8.4mm spherical GP center with a Dk of 130 and a silicone hydrogel peripheral skirt with a Dk of 84. Parameters of 7.5mm base curve, 14.5mm diameter, and –3.75D power provided a stable visual acuity of 20/30. Her comfort with the lens was excellent; within five days, she was wearing the lens from morning to evening with no objective or subjective signs or symptoms of corneal edema.
Figure 2. The Duette lens on our patient’s right eye.
Figure 3. Optical coherence tomography on-eye imaging of the Duette lens.
This case nicely illustrates a condition that we know little about: the rare subjective intolerance that some patients experience with scleral lenses. I am sure that with time, the etiology of this condition will become clearer. In the meantime, alternative lens designs may provide these patients with improved lens comfort. CLS
Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Contamac. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision.