Corneal thinning disorders often lead to protrusion, irregular astigmatism, and even perforation. Corneal ectasia can also be acquired after the LASIK (Laser Assisted in Situ Keratomileusis) procedure. Corneal ecstatic disease may impair vision which can be restored by optical means such as glasses, soft, or rigid gas permeable contact lenses. However, severe cases may require correction or restoration of tectonic integrity of the cornea by surgical means. Previously, PKP (Penetrating Keratoplasty) was the treatment of choice. Although PKP can be very successful in this subset of patients, limitations of PKP can include high post-op cylinder, side effects from chronic topical steroids, corneal rejection, and recurrence of keratoconus in the donor cornea. Intracorneal ring segments are a new modality in the treatment of corneal ecstatic disorders.
Intrastromal corneal ring segments (ICRSs) are made of PMMA (polymethylmethacrylate). They are implanted in the deep corneal stroma to modify the corneal curvature. This procedure does not involve corneal tissue nor does it invade the central optical zone