INTRASTROMAL CORNEAL RING segments (ICRSs) are polymethyl methacrylate ring segments designed to improve uncorrected and corrected visual acuity for patients who have keratoconus (Asbell, 2006). Unfortunately, patients who have moderate or worse keratoconus often still need specialty lenses to improve visual acuity after ICRS implantation.

One challenge of fitting these patients arises because ICRS can alter corneal topography from a prolate ectasia to one that is more oblate. Therefore, in many cases scleral lenses are the best option to achieve a stabilized fit without exacerbating complications of the epithelial surface over the plastic segments. This case will review a patient who required an ICRS removal secondary to chronic erosion both prior to and after scleral lens wear.

A 55-year-old female keratoconus patient reported for scleral lens evaluation for her left eye. Her right eye had mild keratoconus with uncorrected visual acuity of 20/20 without previous treatment or surgery. Her left eye had 20/400 best corrected visual acuity with manifest refraction and prior history of ICRS surgery of 2 ICRSs with superior and inferior placement. She previously had the upper segment removed after epithelial erosion that resulted in chronic irritation.

Corneal topography OS showed moderate ectasia. Slit lamp exam was remarkable for corneal scarring of her previously removed ICRS and an inferior ICRS with no overlying erosion. Corneoscleral topography revealed moderate scleral shape toricity.

The patient’s left eye was fit with a 16.5-mm scleral lens (sagittal depth of 4,575 µm, landing zone toricity of 237 µm, Acuity 100) with a power of –2.42, which gave her 20/20 acuity.

At follow-up, she reported doing well except for mild irritation of her left eye after lens removal. The scleral lens had adequate central corneal clearance, with 260 microns of clearance over her inferior ICRS (Figure 1). The lens did exhibit 1+ nonwetting. So, an exchange replacement lens was ordered with a polyethylene glycol coating along with a small over-refraction, after which the patient did well for a short time without complaints or complications, except for one more exchange for an additional power adjustment. 

However, 11 months later she complained of chronic irritation of her left eye with scleral lens wear. Scleral lens assessment showed that the lens was still adequately vaulting the cornea, including over the ICRS. After scleral lens removal, fluorescein staining showed epithelial erosions over her inferior ICRS (Figure 2). The patient was referred to her corneal surgeon for successful removal of her remaining ICRS. After her postoperative recovery, she was able to wear the same lens without any further incident. 

 A properly fit scleral lens can provide keratoconus patients who have ICRSs improved visual acuity. Be sure there is a proper vault to prevent possible epithelial irritation. However, as this case illustrates, erosions are possible without lens wear and during lens wear, even with a properly fitting lens.

Reference

1. Asbell P. Corneal Implants in the treatment of ectasia. American Academy of Ophthalmology. Published July 1, 2006. Accessed March 1, 2026. https://www.aao.org/education/current-insight/corneal-implants-in-treatment-of-ectasia#:~:text=Intacs%20corneal%20implants%20were%20first,9)%3A1688%2D1694)