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Hong, Whang, Chung, and Joo: Corneal Collagen Crosslinking in Progressive Keratoconus
Original Article

J Korean Ophthalmol Soc 2016;57(11):1714-1722.

Published online: 25 September 2016

DOI: https://doi.org/10.3341/JKOS.2016.57.11.1714

Corneal Collagen Crosslinking in Progressive Keratoconus

Kyung Euy Hong, MD, Woong-Joo Whang, MD, PhD, So Hyang Chung, MD, PhD, Choun-Ki Joo, MD, PhD

Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea

Address reprint requests to Choun-Ki Joo, MD, PhD Department of Ophthalmology, The Catholic University of Korea Seoul St. Mary's Hospital, #222 Banpo-daero, Seocho-gu, Seoul 06591, Korea Tel: 82-2-2258-1188, Fax: 82-2-599-1173 E-mail: ckjoo@catholic.ac.kr

Received 19 May 2016       Revised 29 July 2016       Accepted 1 November 2016

Copyright © 2016 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 report the clinical efficacy and safety of progressive keratoconic eyes in Korean patients treated with accelerated corneal cross-linking.

Methods

This retrospective study focused on progressive keratoconic eyes in Korean patients that underwent accelerated corneal cross-linking from February 2015 to October 2015. Keratoconus was diagnosed in 45 eyes in 30 patients. After accelerated corneal cross-linking with VibeX rapid solution, best corrected visual acuity, maximum keratometry, mean keratometry, corneal thickness, corneal astigmatism, and endothelial cell count were measured at the preoperative visit and post operation 1 week, 1 month, 3 months, and 6 months.

Results

Best corrected visual acuity (log MAR) was 0.51 ± 0.23 at pre operation and 0.51 ± 0.26 at post operation 6 months, showing no improvement. The maximum keratometry measured with Auto K, Pentacam, and Orbscan II at pre operation was 49.11 ± 4.5 D, 48.37 ± 3.31 D, and 48.98 ± 4.88 D and changed to 49.29 ± 4.34 D, 46.99 ± 3.63 D, and 47.01 ± 3.62 D post-operatively, respectively. Only Pentacam and Orbscan II measurements showed a statistically significant decrease (p < 0.05). Corneal thickness (at the thinnest area) was measured with Pentacam and Orbscan II; pre-operative and post-operative 6 month data showed changes from 485 ± 26.27 and 479.24 ± 27.89 to 471.64 ± 27.12 and 472.52 ± 25.36, respectively. Only the Pentacam method resulted in a statistically significant decrease. Endothelial cell count was measured with confocal microscopy and showed a statistically significant difference between pre-operative 2,857 ± 390.49/mm2 and post-operative 6 month 2,639.21± 249.92/mm2.

Conclusions

This 6-month follow-up study of Korean keratoconus patients who underwent accelerated corneal cross-linking indicates that the method is effective in stabilizing the progression of keratoconus, according to maximum keratometry change. With regard to endothelial cell count change, further long-term evaluation is required. Other than endothelial cell count change, this procedure is expected to show long-term safety comparable to that of conventional corneal cross-linking.

Keywords: Corneal collagen cross-linking, Keratoconus, Keratometry

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Figure 1.
Visual acuity changes in patients. The mean log MAR ± standard deviation, uncorrected and corrected distance visual acuity of patients with keratoconus with thin corneas before and after the accelerated corneal collagen cross-linking. CXL = corneal collagen cross-linking; UDVA = uncorrected distance visual acuity; CDVA = corrected distance visual acuity.
jkos-57-1714f1.tif
Figure 2.
Keratometric changes in patients. The mean ± standard deviation of keratometric changes in Auto Kmax, Pentacam Kmax, ORB scan Kmax before and 1 week, 1 month, 3 month, and 6 months after the accelerated corneal collagen crosslinking in patients with keratoconus with thin corneas. CXL = corneal collagen cross-linking.
jkos-57-1714f2.tif
Figure 3.
Image of demarcation line. Corneal stromal demarcation line image with anterior segment optical coherence tomography 1 month after accelerated corneal collagen cross-linking ([CXL] 8 minutes at 30 mW/cm2, total surface dose of 7.2 J/cm2).
jkos-57-1714f3.tif
Table 1.
Progression of keratoconus during preoperative 12 months in patients
Subject ref. CDVA (log MAR) line change Kmax change (D) Kmean change (D)
1 2 2.5 1.8
2 2 2 1.4
3 2 1.5 1.5
4 2 2.5 1.8
5 4 1.6 1.4
6 2 1.3 1.2
7 2 1.2 1
8 3 1.4 1
9 2 2.5 1.5
10 2 2.2 1.9
11 2 2.7 1.7
12 2 1.7 1.2
13 3 7.5 1.5
14 2 2.7 1.3
15 2 1.2 1
16 2 1.5 1.0
17 2 2.2 1.9
18 2 1.6 1.4
19 3 1.3 1.2
20 2 1.1 1.8
21 2 1.5 1
22 2 1.4 2.1
23 2 1.4 1.2
24 2 1.7 1.4
25 2 1.5 1.6
26 2 1.6 1.6
27 2 1.7 1.4
28 2 2.2 1.5
29 2 2.3 1.3
30 3 1.6 1.5
31 4 1.5 1.4
32 2 1.6 1.3
33 2 1.2 1.6
34 2 1.2 1.5
35 2 1.5 1.8
36 2 1.5 1.3
37 2 1.2 0.8
38 2 1.6 0.9
39 3 1.7 1.1
40 2 1.7 0.5
41 2 1.2 1
42 2 2.9 1.1
43 2 1.6 1.3
44 2 1.8 1.1
45 2 1.2 1

CDVA = corrected distance visual acuity.

Table 2.
Visual refractive and topographic al parameters on preoperativ ve assessment and at fo llow up (n = 45)
  Mean before CXL Mean after CXL Difference p-value
CDVA (log MAR) 0.51 ± 0.23 0.51 ± 0.26 0 ± 0.26 0.985
Spherical error (D) –4.85 ± 3.86 –4.98 ± 3.68 0.13 ± 1.7 0.707
Cylindrical error (D) –3.96 ± 2.52 –3.98 ± 2.53 0.02 ± 1.71 0.954
Spherical equivalent –6.86 ± 4.25 –6.9 ± 4.15 0.04 ± 1.64 0.904
Auto Kmax (D) 49.11 ± 4.5 49.29 ± 4.34 –0.18 ± 3.58 0.804
Astigmatism by AutoK (D) 4.70 ± 2.64 4.58 ± 2.42 0.12 ± 1.70 0.750
Pentacam Kmax (D) 48.37 ± 3.31 46.99 ± 3.63 1.38 ± 1.27 0
Astigmatism by Pentacam (D) 4.55 ± 2.71 4.40 ± 2.52 0.15 ± 1.74 0.711
ORBscan Kmax (D) 48.98 ± 4.88 47.01 ± 3.62 1.96 ± 2.02 0
Astigmatism by ORBscan (D) 4.77 ± 2.98 4.61 ± 2.88 0.16 ± 1.90 0.650
Apex corneal thickness on Pentacam (μm) 485 ± 26.27 471.64 ± 27.12 13.36 ± 12.33 0
Apex corneal thickness on ORB scan (μm) 479.24 ± 27.89 472.52 ± 25.36 6.72 ± 18.18 0.077
Endothelial cell density (cells/mm2) 2857 ± 390.49 2639.21 ± 249.92 218.32 ± 400.24 0.012

Values are presented as mean ± SD unless otherwise indicated.

CXL = corneal collagen cross-linking; CDVA = corrected distance visual acuity.

Table 3.
Visual topographical correlation between preoperative parameters and the degree of postoperative corneal flattening using Pentacam method
  Pentacam Kmean (D)
 Difference p-value
Before CXL After CXL
Pentacam Kmax > 50 (D) before CXL 52.70 ± 1.85 51.49 ± 2.83 1.20 ± 1.26 0.045
Pentacam Kmax ≤ 50 (D) before CXL 46.68 ± 1.88 45.23 ± 2.25 1.45 ± 1.31 0

Values are presented as mean ± SD unless otherwise indicated. CXL = corneal collagen cross-linking.

Table 4.
Visual topographical correlation between preoperative parameters and the degree of postoperative corneal flattening using ORB scan method
  ORB Kmean (D)
 Difference p-value
Before CXL After CXL
ORB Kmax > 50 (D) before CXL 55.02 ± 4.77 51.71 ± 2.52 3.31 ± 3.00 0.027
ORB Kmax ≤ 50 (D) before CXL 46.64 ± 2.18 45.19 ± 1.93 1.44 ± 1.24 0

Values are presented as mean ± SD unless otherwise indicated.

CXL = corneal collagen cross-linking.

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