Scleral contact lenses have benefited from the introduction of new materials and new manufacturing techniques. The result is a contact lens that can overcome corneal irregularity while maintaining clear vision and comfort.
Scleral contact lenses are hardly new, but more oxygen-permeable materials, more sophisticated manufacturing technology, and a growing understanding of their benefits are breathing new life into this modality. Scleral lenses are particularly applicable to patients who can’t be fit with, or are uncomfortable in, rigid gas permeable (GP) lenses, including patients with keratoconus, recurrent epithelial erosion, highly toric or irregular corneas, or those who require post-transplant correction.
Scleral contact lenses are not just larger GP lenses, they act differently on the eye. Scleral lenses come in different lens designs, as well as different sizes. The larger scleral lenses often work well for patients with highly irregular corneas, as the lens simply vaults the area of irregularity. Because scleral lenses are stable, have large optic zones, and utilize spherical optics, they can offer excellent visual results.
Fitting scleral contact lenses requires some practice, but after the initial learning curve, many eyecare practitioners find these lenses easier to fit than standard GP lenses. Scleral contact lenses are fit based on sagittal depth of the lens in relation to the sagittal depth of the cornea. For the initial lens, I usually try to match the curvature of the reference sphere from the topographer. From there, simply observing lens fit will determine whether more or less sagittal depth is needed. When checking the fit, there should be no vascular impingement, conjunctival blanching, or sclera indentation at the lens edge. There should be adequate pooling over the limbal area, which can be observed with fluorescein.
While some patients may have difficulty getting used to inserting scleral lenses (the lens needs to be inserted with a bowl full of preservative-free saline, requiring the patient to be in a nose-down position), most will eventually get it. Upon mastering the technique, both patient and provider will usually agree that the benefits justify the effort.
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