“The pain was unbearable,” is not the typical descriptor heard from your scleral lens patients. This is a case where a misinterpretation of OCT affected a patient’s scleral lens fit.

Case Description

The patient is a 33-year-old white female with long-standing keratoconus. She had epi-off corneal cross-linking in 2019 with a world-famous ophthalmologist. Shortly after, she was fit with scleral lenses by an optometrist in that practice. Initially, her scleral lenses were comfortable, and her vision was outstanding. She left that practice happy. Two months later, her wear time started decreasing. Soon after, she was only able to wear lenses for 3 hours at a time without experiencing pain (OD>OS) and problematic vision, with symptoms of drying, star-bursting, and halos around lights. She stopped wearing lenses all together.

She arrived in our practice in 2023 for her first visit. Corrected vision with scleral lenses was 20/25 OD, 20/20 OS. Spectacle best-corrected vision was 20/40 OD, 20/100 OS. Topography showed inferior steepening. Pachymetry showed thinnest corneal thickness of 430µ OD, 415µ OS. Inspection of habitual scleral lenses using OCT showed appropriate central corneal vault OU, but touch on the limbus in both eyes, with peripheral corneal touch OD (Figure 1a). 

Discussion

The patient consented to a refit of scleral lenses with Ampleye (Art Optical) 8.04/4400/-4.00/16.5/150µ toric PC trial lenses OD and OS. Trial lenses were vastly more comfortable than her habitual lenses. Visual acuity with a large hyperopic over-refraction was found to be 20/20 OD and OS. 

She arrived for her dispensing appointment with excitement. With sclerals inserted, corrected visual acuity was 20/25 OD, and 20/20 OS. Unsettled central vault was measured with OCT to be 308µ OD, 280µ OS. Importantly, there was significant vault at the limbus 360° OD and OS (Figure 1b), and haptics were aligned in all meridians. She commented that although the lenses were comfortable, her vision felt “off.” Wavefront-guided over-refraction yielded +1.75 DS OD and plano OS. Aside from the anisometropia, she was thrilled with the new lenses. She left with this pair until we were able to dispense the next right lens with proper power.

In her final visit of the year, vision was 20/20 OD and OS with plano over-refraction in both eyes. Lenses had central settled vault of 280µ OD and 244µ OS, and importantly, there was limbal clearance in all meridians.

Conclusion

Even in preeminent practices, there is confusion about how to evaluate scleral lenses using OCT. After this patient’s original visit, we obtained the records from the previous fit. The ECP used anterior segment OCT to evaluate the central vault and lens haptics. But it is clear from the images that the OCTs were interpreted incorrectly, with OCT image slices recorded through the peripheral cornea instead of limbus, indicating a misread of the location of the limbus.

Many practitioners are still not using OCT to evaluate their scleral lens fits. For central vault, the slit beam estimation technique has been shown to be wildly inaccurate, even in the best of hands (Brujic, 2016).¹ For evaluating limbal clearance, it can take years of full-time practice with sclerals to master this technique. 

If this is the gold standard for evaluating lenses without OCT, why do practitioners in the United States attend a 2-hour seminar and feel that they have mastered the slit beam estimation technique? Perhaps it is time to set the bar for scleral lens fittings to spending years studying how to evaluate scleral lenses without OCT, or evaluating all fits with OCT. 

Jeffrey Sonsino, OD, practices at Optique Eye Care Eye Wear in Nashville, Tenn. He is a Fellow of the Amercan Academy of Optometry (AAO), and a Diplomate in Cornea, Contact Lenses, and Refractive Technologies of the AAO. He discloses renumeration from ABB Optical Group, Art Optical, Contamac, myEyeris, Visionary Optics, and Visionix.

REFERENCES

1. Brujic M. Estimating Scleral Lens Clearance and Comparing it to OCT Measured Clearance. Poster at Global Specialty Lens Symposium, 2016.