Enhanced effect of double-stacked intrastromal corneal ring segments in keratoconus.

We present a patient with poor visual acuity and contact lens intolerance due to advanced keratoconus who had femtosecond-assisted placement of two 0.35 mm intrastromal corneal ring segments (ICRS) in the right eye. Postoperatively, both rings migrated inferiorly and overlapped each other in a double-stacked formation. This resulted in a dramatic central shift of the cone and flattening of the inferior paracentral cornea with significant improvement in vision. To our knowledge, this is the first report of double-stacked ICRS in a human cornea and raises the possibility that significantly thicker segments may provide enhanced anatomic and visual effects in some keratoectatic patients.