Intrastromal corneal ring segment implantation for high astigmatism after penetrating keratoplasty

To evaluate the safety and efficacy of intracorneal ring segments (ICRS) for high astigmatism after penetrating keratoplasty (PKP).

Department of Ocular Surface and Inflammation, Ophthalmology, Hospital Clínico San Carlos, Complutense University, Madrid, Spain.

This retrospective noncomparative study comprised eyes with high post-PKP astigmatism (>4.00 diopters [D]), contact lens intolerance, and a minimum follow-up of 24 months who had ICRS (Kerarings) implantation by mechanical stromal dissection. Corrected distance visual acuity (CDVA), refractive astigmatism, spherical equivalent (SE), surgically induced astigmatism (SIA), central corneal curvature, topographic corneal astigmatism, average corneal power, and complications were assessed.

The mean CDVA was statistically significantly better postoperatively (0.23 +/- 0.21) than preoperatively (0.98 +/- 0.27) (P = .007); no eye lost CDVA. The mean refractive astigmatism decreased from 6.17 +/- 1.12 D to 4.04 +/- 1.67 D (P = .068) and the mean SE from -3.17 +/- 5.48 D to -0.12 +/- 2.40 D (P = .34). The mean SIA was 4.55 +/- 2.83 D. The mean central corneal curvature decreased from 46.28 +/- 1.73 D to 42.09 +/- 3.20 D (P<.01); the mean topographic corneal astigmatism, from 7.07 +/- 2.52 D to 4.48 +/- 2.00 D (P<.05) and the mean average corneal power from 45.92 +/- 1.59 D to 41.88 +/- 3.37 D (P<.01); all decreases were statistically significant. One patient developed deep vascularization in the lower temporal stromal channel that resolved after ICRS removal. One patient reported significant night halos.

Implantation of ICRS for high post-PKP astigmatism reduced corneal curvature and topographic astigmatism, significantly improving CDVA.