Intracorneal Ring Segment Implantation for the Management of Keratoconus: Short-Term Safety and Efficacy

Ho Soong Kim; Tae Hun Lee; Kyung Hun Lee

doi:10.3341/jkos.2009.50.10.1505

Journal List > J Korean Ophthalmol Soc > v.50(10) > 1008388

Go to TopGo to Top Go to BottomGo to Bottom

TOOLS

Kim, Lee, and Lee: Intracorneal Ring Segment Implantation for the Management of Keratoconus: Short-Term Safety and Efficacy

Original Article

J Korean Ophthalmol Soc 2009;50(10):1505-1509.

Published online: 3 August 2009

DOI: https://doi.org/10.3341/jkos.2009.50.10.1505

Intracorneal Ring Segment Implantation for the Management of Keratoconus: Short-Term Safety and Efficacy

Ho Soong Kim, MD¹, Tae Hun Lee, MD², Kyung Hun Lee, MD¹

¹Sungmo Eye Hospital, Busan, Korea

²St. Mary’s Lasik Center, Busan, Korea

Address reprint requests to Tae Hun Lee, MD Sungmo Eye Hospital #1078-7 Woo 2-dong, Haeundae-gu, Busan 612-823, Korea Tel: 82-51-743-0775, Fax: 82-51-743-0776, E-mail: Styie1@empal.com

Received 3 April 2009 Accepted 30 June 2009

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 assess the safety and efficacy of intracorneal ring segment (Intacs ring) implantation in managing keratoconus.

Methods

This retrospective case series comprised of 11 keratoconic eyes (11 patients) had Intacs ring (Addition Technology, Inc, California, USA) implantation. The main outcome measures were best corrected visual acuity, refraction, keratometry, topography, and pachymetry. Patients were examined before Intacs ring implantation as well as one week, one, three, and six months postoperatively.

Results

The mean best corrected visual acuity improved from 0.60±0.33 logMAR preoperatively to 0.39±0.23 logMAR six months postoperatively (p >0.05) and the mean corneal thickness, from 432.82±41.17 μm preoperatively to 448.00±62.27 μm at six months (p >0.05). The mean cylinder improved from -5.36±2.70D preoperatively to -2.50±1.66D six months postoperatively (p <0.05) and the mean keratometry, from 47.99±2.38D to 42.83±1.72D at six months (p <0.05). In addition, the mean spherical equivalent improved from -6.64±3.49D preoperatively to -3.66±3.37D six months postoperatively (p <0.05). One eye had a risk of ring exposure, but the others had no significant complications.

Conclusions

Intacs ring implantation appears to be effective in improving cylinder, spherical equivalent, and keratometry in patients with keratoconus.

Keywords: Intacs, Intracorneal ring segment, Keratoconus

References

1. Rathi VM, Krishnamachary M, Gupta S. Cataract formation after penetrating keratoplasty. J Cataract Refract Surg. 1997; 23:562–4.

2. Ing JJ, Ing HH, Nelson LR, et al. Ten-year postoperative results of penetrating keratoplasty. Ophthalmology. 1998; 105:1855–65.

3. Colin J, Cochener B, Savary G, Malet F. Correcting keratoconus with intracorneal rings. J Cataract Refract Surg. 2000; 26:1117–22.

4. Siganos CS, Kymionis GD, Kartakis N, et al. Management of keratoconus with Intacs. Am J Ophthalmol. 2003; 135:64–70.

5. Hellstedt T, Makela J, Uusitalo R, et al. Treating keratoconus with intacs corneal ring segments. J Refract Surg. 2005; 21:236–46.

6. Meek KM, Tuft SJ, Huang Y, et al. Changes in collagen orientation and distribution in keratoconus corneas. Invest Ophthalmol Vis Sci. 2005; 46:1948–56.

7. Troutman RC, Gaster RN. Surgical advances and results of keratoconus. Am J Ophthalmol. 1980; 90:131–6.

8. Frost NA, Wu J, Lai TF, Coster DJ. A review of randomized controlled trials of penetrating keratoplasty techniques. Ophthalmology. 2006; 113:942–9.

9. Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003; 135:620–7.

10. Alio JL, Shabayek MH, Belda JI, et al. Analysis of results related to good and bad outcomes of Intacs implantation for keratoconus correction. J Cataract Refract Surg. 2006; 32:756–61.

11. Guell JL. Are intracorneal rings still useful in refractive surgery? Curr Opin Ophthalmol. 2005; 16:260–5.

12. Sharma M, Boxer Wachler BS. Comparison of single-segment and double-segment Intacs for keratoconus and post-LASIK ectasia. Am J Ophthalmol. 2006; 141:891–5.

13. Chan SM, Khan HN. Reversibility and exchangeability of intrastromal corneal ring segments. J Cataract Refract Surg. 2002; 28:676–81.

14. Zare MA, Hashemi H, Salari MR. Intracorneal ring segment implantation for the management of keratoconus: safety and efficacy. J Cataract Refract Surg. 2007; 33:1886–91.

15. Rabinowitz YS. INTACS for keratoconus. Int Ophthalmol Clin. 2006; 46:91–103.

16. Ratkay-Traub I, Ferincz IE, Juhasz T, et al. First clinical results with the femtosecond neodynium-glass laser in refractive surgery. J Refract Surg. 2003; 19:94–103.

17. Coskunseven E, Kymionis GD, Tsiklis NS, et al. One-year results of intrastromal corneal ring segment implantation (KeraRing) using femtosecond laser in patients with keratoconus. Am J Ophthalmol. 2008; 145:775–9.

18. Kymionis GD, Siganos CS, Tsiklis NS, et al. Long-term follow-up of Intacs in keratoconus. Am J Ophthalmol. 2007; 143:236–44.

19. Ruckhofer J, Twa MD, Schanzlin DJ. Clinical characteristics of lamellar channel deposits after implantation of intacs. J Cataract Refract Surg. 2000; 26:1473–9.

20. Randleman JB, Dawson DG, Larson PM, et al. Chronic pain after Intacs implantation. J Cataract Refract Surg. 2006; 32:875–8.

Table 1.

Nomogram for Intacs ring size selection (Addition Technology, Inc, California, USA)

Symmetric
Spherical equivalent		Intacs
+7.00 to +1.00		0.21 mm
+0.75 to -1.75		0.25 mm
-2.00 to -2.75		0.30 mm
-3.00 to -3.75		0.35 mm
-4.00 to -4.75		0.40 mm
-5.00 to -5.75		0.45 mm
-6.00 to -7.75		0.40 mm SK
-8.00 and higher		0.45 mm SK
Asymmetric
Spherical	Inferior	Superior
equivalent	Intacs	Intacs
+1.00 to -2.00	0.30 mm	0.21 mm
-2.00 to -3.00	0.35 mm	0.21 mm
-3.00 to -4.00	0.40 mm	0.21 mm
-4.00 and higher	0.45 mm	0.21 mm

Table 2.

Preoperative and postoperative patient data in patients with keratoconus who underwent Intacs ring implantation

Parameter	Mean± SD
Parameter	Preoperative	1 week	1 month	3 months	6 months
BCVA^* (logMAR)	0.60±0.33	0.53±0.29	0.50±0.20	0.45±0.32	0.39±0.23
Cylinder (D)	-5.36±2.70	-3.14±2.29	-4.09±3.83	-3.50±1.58	-2.50±1.66^§
Spherical equivalent (D)	-6.64±3.49	-2.43±3.78^‡	-4.91±5.21	-5.38±3.68	-3.66±3.37^§
Mean keratometry (D)	47.99±2.38	41.36±2.90^‡	42.98±2.81^‡	42.99±2.89^§	42.83±1.72^‡
Pachymetry^† (µm)	432.82±41.17	448.18±58.07	435.64±53.51	431.27±47.30	448.00±62.27

^* BCVA=best corrected visual acuity;

^† Pachymetry=thinnest point;

^‡ p<0.01;

^§ p=0.01.

Table 3.

Characteristics and outcomes of patients who underwent Intacs ring implantation

Case No.			PreOP					PostOP 6 months
Case No.	Age	Sex	BCVA^*(logMAR)	SE^†(D)	Cylinder (D)	Mean K^‡(D)	Pachymetry^§(µm)	BCVA^*(logMAR)	) SE^†(D)	Cylinder (D)	Mean K^‡(D)	Pachymetry^§(μm)
1	31	M	1.00	-7.50	-5.00	49.40	408	0.15	-7.00	-4.00	43.80	554
2	32	M	1.00	-6.00	-4.00	45.00	442	0.22	-0.75	-1.50	40.00	421
3	32	M	0.40	-8.50	-4.00	48.70	368	0.52	-9.50	-1.00	44.60	378
4	31	F	0.52	-8.00	0.00	49.50	457	0.70	-6.75	-4.50	41.50	420
5	29	M	0.40	-4.50	-9.00	45.00	449	0.10	-0.50	-3.00	42.50	468
6	31	M	0.40	0.00	-6.00	47.80	506	0.70	-0.88	-1.75	45.60	517
7	29	M	0.10	-4.00	-5.00	43.60	478	0.05	0.50	-2.00	40.70	514
8	31	M	0.40	-3.25	-3.50	49.30	448	0.52	-1.13	-1.25	42.90	468
9	31	F	1.00	-8.50	-5.00	50.40	399	0.52	-4.50	-3.00	44.30	432
10	20	M	0.40	-11.50	-9.00	48.60	385	0.40	-3.25	-5.50	43.30	354
11	32	F	1.00	-11.25	-8.50	50.60	421	0.40	-6.50	0.00	41.90	402

^* BCVA=best corrected visual acuity;

^† SE=spherical equivalent;

^‡ K=keratometry;

^§ pachymetry=thinnest point.

Table 4.

Mean best corrected visual acuity (logMAR), spherical equivalent (diopter) and cylinder (diopter) outcomes by preoperative mean keratometry

Preoperative Keratometry (D)	Mean BCVA^* (logMAR)± SD		Mean SE^†± SD		Mean Cylinder± SD
Preoperative Keratometry (D)	PreOP	6-Month PostOP	PreOP	6-Month PostOP	PreOP	6-Month PostOP
<49 (6 eyes)	0.45±0.29	0.33±0.25	-5.75±3.96	-2.40±3.69	-6.17±2.32	-2.46±1.63^‡
≥49 (5 eyes)	0.78±0.30	0.46±0.20	-7.70±2.88	-5.18±2.47^§	-4.40±3.07	-2.55±1.89

^* BCVA=best corrected visual acuity;

^† SE=spherical equivalent;

^‡ p<0.01;

^§ p=0.04.

TOOLS

Similar articles