Practitioners frequently turn to scleral lenses to manage the most challenging corneal shapes, sizes, and conditions. The vast majority of challenging cases can be managed with conventional scleral lenses, which utilize diagnostic sets and parameter adjustments to achieve a successful fit. However, there are occasions when a practitioner may need to turn to an alternative option.

A 60-year-old Caucasian female presented with significantly asymmetric corneal ectasia—keratoglobus in her right eye and mild keratoconus in her left eye (Figure 1). She was referred for a specialty contact lens fitting due to lack of success in fitting a conventional scleral lens on the right eye. The referring practitioner reported that even with the largest and deepest sagittal depth trial in their diagnostic set, there was still significant corneal bearing and lens ejection.

What can be done when conventional sclerals fail? Considerations for this patient were to use scleral topography or impression technology to achieve a customized and more precise fit. Given the challenging shape of both the cornea and the sclera in the right eye, impression-molded sclerals were chosen.

Patients undergoing the ocular surface impression process must be out of contact lenses for two to seven days, depending on their habitual lens type, prior to the procedure. This allows for the eye’s scleral shape to rebound to its baseline position. A polymer is applied to the eye for approximately one to two minutes until it sets and can be removed, but this setting time can vary based on room temperature and humidity (Figure 2). Anesthetic is not required, but it can help minimize tearing, which can cause unwanted channels in the impression. The impression mold is then used to produce a free-form scleral lens (Figure 3). These lenses are then manufactured with great accuracy to closely match the contour of the corneal and scleral surfaces, resulting in a comfortable lens that is highly customized to an individual’s eye shape.

The fit achieved complete corneal vault without any issues of lens ejection. The patient was able to comfortably wear her impression-based scleral lens on the right eye (Figure 4) and she continued to wear a corneal GP on her left eye.

As scleral lens innovation evolves, it is important to understand the available options when the limitations of conventional scleral lenses are reached. Impression-molded technology provides a highly customized fit that can provide excellent comfort, and in some cases achieve better vision for patients when other lenses have failed. The fitting process is also more efficient than a standard scleral fitting, requiring fewer remakes of lenses (Nau et al, 2021; Silverman et al, 2021). CLS

References

1. Nau A, Shorter ES, Harthan JS, Fogt JS, Nau CB, Schornack M. Multicenter review of impression-based scleral devices. Cont Lens Anterior Eye. 2021 Oct;44:101380.
2. Silverman JIM, Huffman JM, Zimmerman MB, Ling JJ, Greiner MA. Indications for Wear, Visual Outcomes, and Complications of Custom Imprint 3D Scanned Scleral Contact Lens Use. Cornea. 2021 May 1;40:596-602.