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Intrastromal Corneal Ring Segments Implantation After Deep Anterior Lamellar Keratoplasty for Astigmatism Correction: Mid-term and Long-term Follow-up.

PURPOSE
The aim of this study was to assess the long-term outcomes of implanting intrastromal corneal ring segments (ICRSs) using a femtosecond laser for correcting astigmatism in patients who had previous deep anterior lamellar keratoplasty (DALK) throughout a 5-year follow-up period.


METHODS
This retrospective study included 40 eyes of 40 patients with previous DALK and astigmatism ≥3.00 D who underwent Ferrara-type ICRS implantation. The manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuity (logMAR), and corneal topography were recorded preoperatively and at 6, 12, 36, and 60 months postoperatively.


RESULTS
The mean UDVA (logMAR scale) improved from 1.39 ± 0.55 preoperatively to 0.71 ± 0.37 at 6 months postoperatively (P < 0.0001). The mean CDVA (logMAR) significantly improved from 0.36 ± 0.17 to 0.22 ± 0.12 at 6 months after surgery (P < 0.0001). Both UDVA and CDVA remained unchanged throughout the follow-up (P = 0.09). Postoperatively, no eyes lost lines of CDVA compared to preoperatively, and around 80% of the eyes gained lines of CDVA. The safety index remained stable at a value of 1.4 throughout the follow-up. The refractive cylinder decreased from -6.86 ± 2.62 D preoperatively to -2.33 ± 1.09D at 6 months postoperatively (P < 0.0001), and subsequently, it was stable over the postoperative period (P = 0.2). The maximum and minimum keratometry measurements significantly decreased after surgery and remained stable over the postoperative follow-up period (P > 0.07).


CONCLUSIONS
This study shows the long-term viability of Ferrara-type ICRS implantation using a femtosecond laser as a surgical alternative for astigmatism correction in post-DALK eyes.