Intrastromal corneal ring segment implantation for high astigmatism after penetrating keratoplasty

Abstract

PURPOSE: To evaluate the safety and efficacy of intracorneal ring segments (ICRS) for high astigmatism after penetrating keratoplasty (PKP). SETTING:METHODS: 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. RESULTS:The mean CDVA was statistically significantly better postoperatively (0.23 G 0.21) than preoperatively (0.98 G 0.27) (P Z .007); no eye lost CDVA. The mean refractive astigmatism decreased from 6.17 G 1.12 D to 4.04 G 1.67 D (P Z .068) and the mean SE from À3.17 G 5.48 D to À0.12 G 2.40 D (P Z .34). The mean SIA was 4.55 G 2.83 D. The mean central corneal curvature decreased from 46.28 G 1.73 D to 42.09 G 3.20 D (P<.01); the mean topographic corneal astigmatism, from 7.07 G 2.52 D to 4.48 G 2.00 D (P<.05) and the mean average corneal power from 45.92 G 1.59 D to 41.88 G 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.CONCLUSION: Implantation of ICRS for high post-PKP astigmatism reduced corneal curvature and topographic astigmatism, significantly improving CDVA.

Intrastromal corneal ring segment implantation to correct astigmatism after penetrating keratoplasty

“…According to Coskunseven et al, eyes with thin corneal grafts and recurrent keratoconus are unsuitable for laser refractive corrections because of the possibility of postoperative complications. In addition, Arriola-Villalobos et al, 5 in a series of 9 patients, found that ICRS implantation improved the CDVA in all eyes and decreased the topographic mean, minimum, and maximum K values. They conclude that ICRS implantation might be a good surgical choice to correct high astigmatism after PKP and yields good visual, refractive, and topographic outcomes.…”

“…We proceeded as Arriola-Villalobos et al 5 suggest; that is, we waited at least 2 years after corneal transplantation and a minimum of 6 months after suture removal to avoid damaging the interface by the traction generated by the dissectors used during surgery in the manual technique.…”

“…Contact lenses are a better choice than spectacles to correct astigmatism because they provide better quality of vision. 5,6 Moreover, the corrected distance visual acuity (CDVA) with contact lenses is usually better than with spectacles in this type of astigmatism. When optical methods fail to achieve satisfactory visual rehabilitation, surgical treatment may be necessary.…”

Management of Post-Penetrating Keratoplasty Astigmatism

“…34 However, several complications were encountered during and after Kerarings implantation including small dehiscence of grafthost interface during stroma tunnel dissection, an inflammatory infiltrate around the segment immediately after operation, stromal channel vascularization leading to ring explantation and night halos. 34 …”

Implantation of intrastromal corneal ring segments for post-keratoplasty astigmatism

“…Moreover, ICRS implantation appears to reduce corneal curvature and topographic astigmatism, providing satisfactory visual results, but the effect of this reduction on refractive astigmatism is not significant. 3 It is also important to remember that ICRS nomograms are designed for keratoconus treatment, as recognized by the authors, and they are based on subjective empirical data, although the complex biomechanical alterations after ICRS implantation necessitate a more sophisticated mathematical model for analyzing the corneal ring effect. 4 This may represent a possible explanation for the low predictability of ICRS implantation in the surgical treatment of post-PKP astigmatism, at least to some extent.…”