Contact Lens Case Reports

The Unknowns of Scleral Lenses

BY PATRICK J. CAROLINE, FAAO , & MARK P. ANDRÉ, FAAO

When addressing irregular corneas, we have four GP contact lens options: corneal spherical or aspheric lenses, piggyback lenses, hybrid lenses, and scleral lenses (Figure 1). Unquestionably, there has been a large increase in the use of scleral contact lenses (Figure 2) over the past five years. While scleral lenses remain an exciting modality for some patients, their over-use is quite premature.

Figure 1. The four rigid lens options for managing irregular corneas.

Figure 2. A well-fitted scleral contact lens with corneal clearance, limbal clearance, and landing on the sclera.

Ongoing research at Pacific University reveals that there remains much we don’t know about current scleral lenses.

Questions to Consider

The answers to the following questions will be critical to the long-term success of the modality.

1. How much corneal swelling takes place beneath a scleral contact lens over a 12-hour period?

2. How much tear exchange takes place beneath a scleral lens over a 12-hour period?

3. What are the long-term effects of scleral contact lenses on the cornea, limbus, conjunctiva, and sclera?

4. Should scleral contact lenses be designed to clear (vault over) or to land on the cornea and/or limbus?

5. What is the best anterior and posterior design for a scleral lens?

6. What is the optimum center thickness for a scleral contact lens?

7. What are the “settling effects” of scleral contact lenses (onto the bulbar conjunctiva) after one hour, four hours, eight hours, and 12 hours of wear?

8. What is the best post-lens tear film thickness for a scleral contact lens?

9. Does lens diameter and/or design affect any of the above?

10. What is the actual shape of the sclera, and is it symmetrical 360 degrees around the eye?

11. Is the sclera similar in shape (right eye versus left eye)?

12. What are the differences in scleral shape between non-diseased and diseased eyes?

13. Is saline (with its lack of nutrients) the best post-lens solution?

14. How do we best manage the unique scleral complications of tear film fogging, conjunctival prolapse, conjunctival compression, post-lens mucus and debris, and post-penetrating keratoplasty corneal edema?

Where Things Stand

As of now, we have only a limited understanding about the design, fitting, and long-term ramifications of scleral lenses. At Pacific, these questions preoccupy us every day. So we teach our students that when indicated, corneal and piggyback contact lenses remain the modalities of first choice when managing irregular corneas. We remain huge advocates of scleral contact lenses, but for use only in cases of 1) managing ocular surface disease or 2) when corneas exhibit asymmetric height differences that prohibit the successful fitting of a corneal contact lens design.

We need to continue our research into both advanced corneal and scleral contact lens designs— both modalities are critical in today’s management of irregular corneas. CLS

Patrick Caroline is an associate professor of optometry at Pacific University. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for Cooper-Vision.