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Ha, Choi, Lee, and Kim: The Clinical Results of Intrastromal Corneal Ring Segment Implantation Using a Femtosecond Laser in Keratectasia
Original Article

J Korean Ophthalmol Soc 2010;51(1):1-7.

Published online: 7 September 2010

DOI: https://doi.org/10.3341/jkos.2010.51.1.1

The Clinical Results of Intrastromal Corneal Ring Segment Implantation Using a Femtosecond Laser in Keratectasia

Chang II Ha, MD, Suk Kyue Choi, MD, Do Hyung Lee, MD, PhD, Jin Hyoung Kim, MD

Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine, Ilsan, Korea

Address reprint requests to Jin Hyoung Kim, MD Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine #2240 Daehwa-dong, Ilsanseo-gu, Goyang 411-760, Korea Tel: 82-31-910-7240, Fax: 82-31-911-7241, E-mail: jhk0924@hanmail.net

Received 1 June 2009       Accepted 22 September 2009

Copyright © 2010 Korean Ophthalmological Society

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

To evaluate the clinical results of intrastromal ring segment (Keraring®) implantation using a femtosecond laser in patients with keratectasia.

Methods

Twenty eyes of 19 keratectatic patients (15 eyes of keratoconus and five eyes of post-LASIK keratectasia) who completed at least three months of postoperative follow-up were included in this study. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), spherical equivalent, keratometric value, corneal astigmatism, corneal higher order aberrations (HOA) and specular microscopy were determined or performed before and after surgery. In addition, intraoperative and postoperative adverse complications were recorded.

Results

UCVA improved in 13 out of 20 eyes (65%), and BSCVA improved in 16 out of 20 eyes (80%). At the postoperative examination there was no statistically significant reduction in the spherical equivalent with that observed at the examination before implantation. Conversely, there were statistically significant reductions in topographic mean K value and Sim K astigmatism, corneal total and comalike HOA (p<0.05). On specular microscopy, there was no statistically significant difference between preoperative and postoperative endothelial cell density. There was one case of partial Descemet membrane detachment and one case of microperforation as a complication during surgery, which recovered over time without any treatment.

Conclusion

Keraring® implantation appears to be an effective and safe procedure for improving visual acuity and stabilizing corneal refractive power in keratectactic patients.

Keywords: Femtosecond laser, Intrastromal corneal ring segment, Keratectasia

References

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Figure 1.
Bar graphs demonstrating (left) uncorrected visual acuity (UCVA) and (right) best spectacle-corrected visual acuity (BSCVA) changes after intrastromal corneal ring segment (ICRS, Keraring®) implantation in keratectatic patients.
jkos-51-1f1.tif
Table 1.
Technical specification of Femtosecond laser and Keraring® in patients
Parameter Femtosecond laser
Tunnel depth in cornea (mean± SD) 407.7±43.9 μm (range: 340∼480)
Inner diameter 5.0 mm
Outer diameter 5.8 mm
Ring energy 1.50 μJ
Entry cut energy 1.50 μJ
Entry cut length 1.10 mm
Entry cut thickness 1.0 μm
Parameter Keraring®
Design(Cross-section) Triangular
Implantation in respect to Center of visual axis
Implantation depth 80% of the corneal thickness
Arc length 90, 120, 160 and 210 degree
Available segment thickness 150, 200, 250, 300 and 350 μm
Table 2.
Demographics of patients undergoing intrastromal corneal ring segment (Keraring®) implantation
Number of patients 19
Number of eyes 20
 Keratoconus: Post-LASIK keratectasia 15: 5
Gender
 Male: Female 12: 7
Age (years)
 Mean± SD* 29.2±9.8
 Range 14 to 45
Follow-up (months)
 Mean± SD 6.0±3.9
 Range 3 to 15

* SD=standard deviation.

Table 3.
Preoperative and postoperative data of patients with keratectasia after intrastromal corneal ring segment (Keraring®) implantation
Parameter Preoperative Postoperative 3 months p-value§ Last postoperativeΠ p-value
Spherical equivalent (D*)
 Mean± SD† −8.09±6.70 −6.66±6.03 0.067 −6.87±6.09 0.076
 Range −21.00 to +2.00 −20.00 to +1.00 −20.50 to +1.50
Topo mean K (D)
 Mean± SD 52.04±5.74 50.07±5.63 0.001 50.23±5.96 0.001
 Range 42.45 to 68.40 42.35 to 65.60 41.50 to 66.70
Sim K astigmatism (D)
 Mean± SD −5.21±3.29 −3.47±2.00 0.015 −3.31±1.87 0.007
 Range −13.90 to −1.50 −7.40 to −0.90 −7.20 to −0.80
Cornea total HOA‡ (μm)
 Mean± SD 5.809±5.253 3.438±1.740 0.009 3.453±1.781 0.009
 Range 2.055 to 23.563 1.548 to 6.900 1.548 to 6.900
Cornea comalike HOA (μm)
 Mean± SD 5.319±4.582 2.969±1.536 0.003 3.023±1.605 0.003
 Range 1.954 to 20.743 1.408 to 5.847 1.354 to 5.847

* D=diopter

† SD=standard deviation

‡ HOA=higher order aberration

§ Wilcoxon signed rank test

Π Last postoperative=6.0±3.9 months (Mean± SD) (range: 3∼15 months).

Table 4.
Results of preoperative and postoperative endothelial cell density (CD, cells/±)
Mean± SD* Range p-value†
Preoperative 2379.7±369.5 2028∼2985
Postoperative 1 week 2338.3±366.4 1976∼2777 0.499
Postoperative 1 month 2338.8±232.5 1982∼2712 0.866

Total N =7

* SD=standard deviation

† Wilcoxon signed rank test.

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