A KERATOCONUS AND POST-GRAFT patient was one of the first that I fitted with scleral lenses more than 10 years ago. Then, he was 64 years old, working as a truck driver, and looking to improve his comfort and vision by being fitted with GP lenses.

The scleral lenses made a marked difference for this patient. During all these years, he has been very compliant, has been seen frequently, and his lenses have been replaced every two years. The story could end there, without the spectacular fall or cliffhanger often found in good movies. But his latest chapter brought surprises. At the patient’s last visit, when he told me that he was finally retiring, his lens replacement was not as easy as the previous ones had been.

I had not made changes to the design and fit of the previous lenses. I simply asked the laboratory for a duplicate of the existing lenses. In such cases, dispensing of the lenses is made without an appointment, while advising the patient to come back if something goes wrong. A few days after, the patient came back into the office with temporal ocular redness that was segment-shaped in both eyes. Discomfort forced him to remove his lenses sooner than desired. With time, it got even worse.

HOW CAN WE EXPLAIN THIS?

There are many reasons why a newly dispensed scleral lens does not seem to function properly:

• Lens is placed on the wrong eye.
• Patient begins taking a new “natural product” or topical/systemic medication.
• Sudden change in systemic/ocular health (e.g., hyperthyroidism).
• Improper handling of lens.
• Patient experiences an inflammatory reaction (that may or may not be related to lens wear).
• There was an error in the ordering or manufacturing of the lens.

Simply put, either the lens is not the exact duplicate of the older one, or the eye condition or the patient’s behavior has changed.

This happens with corneal GP lenses; because the lenses are worn for many years, they may become warped over time. Their curves become flatter or toric. The cornea may become warped also, in consequence. So, a new lens, made according to the previous parameters, does not fit. This is not applicable to scleral lens wear.

When this patient came back, analysis of the scleral lenses confirmed that the base curve and lens power were accurate. There had been no lens reversal. Lens handling was adequate. Slit lamp examination showed a compression of the conjunctiva temporally, generating redness around the scleral lens.

Upon removal, a conjunctival indentation was visible, which had never been noticed before. Clearly, the lenses were too tight in one particular meridian, which was surprising, as they were supposed to be a perfect copy of those successfully prescribed 17 months prior.

BUYER BEWARE

It can be difficult to analyze and cross-check the peripheral curvatures of a scleral lens. On the packing slip, the lens parameters listed were identical to those on the previous order. This left only the hypothesis of a change in the manufacturing of the lenses.

A call to the laboratory’s consulting department confirmed that changes had been made to the calibration of the edging devices (lathe), but that it was not expected that this routine maintenance procedure could change the lens parameters. However, in this case, it took two more pairs of lenses to finally get back to a comfortable wear, so that the patient could fully enjoy his retirement.

Practitioners agree that scleral lenses are becoming more and more complex to manufacture (quadrant-specific, etc.). It is also logical to expect periodic maintenance of the machinery to be performed. We understand all of this. But in an ideal world, laboratories should notify us when they make important changes to the production line that may affect the final result. We can then prevent issues and manage patients’ expectations. After all, we are all one team, so we can all serve our patients better! CLS