Outcomes of Small Incision Lenticule Extraction: Mild to Moderate Myopia versus High Myopia

Jae Ryun Kim; Hyun Seung Kim; Su Joung Mun; Young Taek Chung

doi:10.3341/jkos.2014.55.7.963

Journal List > J Korean Ophthalmol Soc > v.55(7) > 1010012

Go to TopGo to Top Go to BottomGo to Bottom

TOOLS

Kim, Kim, Mun, and Chung: Outcomes of Small Incision Lenticule Extraction: Mild to Moderate Myopia versus High Myopia

Original Article

J Korean Ophthalmol Soc 2014;55(7):963-968.

Published online: 30 August 2014

DOI: https://doi.org/10.3341/jkos.2014.55.7.963

Outcomes of Small Incision Lenticule Extraction: Mild to Moderate Myopia versus High Myopia

Jae Ryun Kim, MD¹, Hyun Seung Kim, MD, PhD¹, Su Joung Mun, MD, PhD², Young Taek Chung, MD, PhD²

¹Department of Ophthalmology and Visual Science, The Catholic University of Korea College of Medicine, Seoul, Korea

²Onnuri Eye Clinic, Jeonju, Korea

Address reprint requests to Young Taek Chung, MD, PhD, Onnuri Eye Clinic, #5 Meneomeo 2-gil, Wansan-gu, Jeonju 560-838, Korea, Tel: 82-63-277-2774, Fax: 82-63-278-8701 E-mail: eyegreen@eyegreen.com

Received 28 February 2014 Revised 25 April 2014 Accepted 24 June 2014

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 refractive outcomes of small incision lenticule extraction (SMILE) in high myopia patients compared with mild to moderate myopia patients.

Methods

This study included 332 eyes of 166 myopic patients treated with SMILE using Visumax 500 kHz femtosecond laser. Treated eyes were divided into 2 groups according to preoperative spherical equivalent (SE): mild to moderate myopia (A group, <-6.0 D) and high myopia (B group, >-6.0 D). Follow-up visits were at 1 day, 1 week, 1 month, 3 months, and 6 months. The out-come measures included uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (BDVA), post-operative SE, efficacy index, safety index and predictability.

Results

Preoperative SE was −4.85 ± 0.86 D in the A group and −7.70 ± 1.0 D in the B group. No differences were observed between −0.04 ± 0.29 D in the A group and −0.30 ± 0.37 D in the B group at 6 months postoperatively (p = 0.062). At 6 months post-operatively, 98.3% and 97.3% had UDVA of 20/25 or better in the A group and B group, respectively. In the A group, 97.3% and 100% were within ±0.5 D and ±1.0 D of intended correction and in the B group, 91.7% and 96.9% were within ±0.5 D and ±1.0 D, respectively. Efficacy indices were 1.02 ± 0.19 in the A group and 0.99 ± 0.18 in the B group. Safety indices were 1.16 ± 0.16 in the A group and 1.14 ± 0.16 in the B group. The efficacy and safety indices were not significantly different between the A and B groups at 6 months postoperatively (p = 0.09, p = 0.695, respectively).

Conclusions

This study showed that SMILE is effective and safe for correcting high myopia as well as mild to moderate myopia.

Keywords: Best corrected distance visual acuity, High myopia, SMILE, Uncorrected distance visual acuity

References

1. Sandoval HP, de Castro LE, Vroman DT, Solomon KD. Refractive Surgery Survey 2004. J Cataract Refract Surg. 2005; 31:221–33.

2. Shtein RM. Post-LASIK dry eye. Expert Rev Ophthalmol. 2011; 6:575–82.

3. Mohammadpour M, Jabbarvand M. Risk factors for ectasia after LASIK. J Cataract Refract Surg. 2008; 34:1056.

4. Kim HJ, Cho SH, Kim JH, Joo CK. Risk factors and clinical evalu-ation for corneal ectasia after LASIK. J Korean Ophthalmol. 2005; 46:589–96.

5. Khoueir Z, Haddad NM, Saad A, et al. Traumatic flap dislocation 10 years after LASIK. Case report and literature review. J Fr Ophtalmol. 2013; 36:82–6.

6. Reinstein DZ, Archer TJ, Randleman JB. Mathematical model to compare the relative tensile strength of the cornea after PRK, LASIK, and small incision lenticule extraction. J Refract Surg. 2013; 29:454–60.

7. Li M, Zhao J, Shen Y, et al. Comparison of dry eye and corneal sensitivity between small incision lenticule extraction and femtosecond LASIK for myopia. PLoS One. 2013; 8:e77797.

8. Shah R, Shah S, Sengupta S. Results of small incision lenticule extraction: All-in-one femtosecond laser refractive surgery. J Cataract Refract Surg. 2011; 37:127–37.

9. Hjortdal JO, Vestergaard AH, Ivarsen A, et al. Predictors for the outcome of small-incision lenticule extraction for Myopia. J Refract Surg. 2012; 28:865–71.

10. Sekundo W, Kunert KS, Blum M. Small incision corneal refractive surgery using the small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism: results of a 6 month prospective study. Br J of Ophthalmol. 2011; 95:335–9.

11. Kamiya K, Shimizu K, Igarashi A, Kobashi H. Visual and refractive outcomes of femtosecond lenticule extraction and small-incision lenticule extraction for myopia. Am J Ophthalmol. 2014; 157:128–34.e2.

12. Vestergaard A, Ivarsen AR, Asp S, Hjortdal JO. Small-incision lenticule extraction for moderate to high myopia: Predictability, safety, and patient satisfaction. J Cataract Refract Surg. 2012; 38:2003–10.

13. Li M, Niu L, Qin B, et al. Confocal comparison of corneal reinnervation after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK). PLoS One. 2013; 8:e81435.

14. Ang M, Chaurasia SS, Angunawela RI, et al. Femtosecond lenticule extraction (FLEx): clinical results, interface evaluation, and intraocular pressure variation. Invest Ophthalmol Vis Sci. 2012; 53:1414–21.

15. Ivarsen A, Asp S, Hjortdal J. Safety and complications of more than 1500 small-incision lenticule extraction procedures. Ophthalmology. 2014; 121:822–8.

Figure 1.

A schematic drawing of cornea in small incision lenticule extraction (SMILE) procedure.

Figure 2.

Safety. Gain and loss of CDVA of 2 groups 6 months postoperatively. CDVA = corrected distance visual acuity; D = diopters.

Figure 3.

Predictability. (A) Bar graph represents the percentage of eyes within ±0.5 D of intended correction at 3 and 6 months postoperatively. (B) The percentage of eyes within ±1.0 D of intended correction. D = diopters; POD = post-operative day.

Table 1.

Demographics of patients

Characteristics	Total	Group A	Group B	p-value
Eyes (n)	332	109	223
Sex (M/F)	102/230	27/82	75/148
Age (years)	27 ± 6 (18-48)	28 ± 7 (18-48)	26 ± 6 (18-48)	0.231
Mean corneal power (diopter)	44.2 ± 1.49 (39.4-48.3)	44.3 ± 1.47 (40.4-47)	44.2 ± 1.51 (39.4-48.3)	0.934
UDVA (log MAR)	1.63 ± 0.25 (0.5-2.0)	1.53 ± 0.31 (0.5-2.0)	1.68 ± 0.19 (0.7-2.0)	0.000^*
CDVA (log MAR)	-0.054 ± 0.05 (-0.2∼0.2)	-0.07 ± 0.05 (-0.2 ∼ 0.1)	-0.05 ± 0.06 (-2∼0.2)	0.003^*
IOP (mm Hg)	15.1 ± 2.62 (8-24)	14.6 ± 2.75 (8-20)	15.4 ± 2.51 (9-24)	0.166
Sphere (diopter)	-6.17 ± 1.68 (-10∼-2.25)	-4.24 ± 0.89 (-5.75∼-2.25)	-7. 07 ± 1.15 (-10 ∼ −4.5)	0.001^*
Cylinder (diopter)	-1.18 ± 0.80 (-4∼0)	-1.03 ± 0.83 (-4∼ 0)	-1.25 ± 0.77 (-4∼0)	0.313
Spherical equivalence (diopter)	-6.76 ± 1.66 (-10.5∼-2.25)	-4.85 ± 0.86 (-5.88∼-2.25)	-7.70 ± 1.04 (-10.50 ∼ −6)	0.004^*
CCT (μm)	525 ± 31 (450∼625)	517 ± 34 (450 ∼ 596)	529 ± 29 (462∼625)	0.007^*
Expected residual corneal bed (μm)	298 ± 28 (450∼625)	311 ± 30 (253∼389)	293 ± 24 (252 ∼389)	0.014^*

Values are presented as mean ± SD.

UDVA = uncorrected distance visual acuity; CDVA = corrected distance visual acuity; log MAR = log of the minimum angle of resolution; IOP = intraocular pressure; CCT = central cornea thickness.

^* p < 0.05.

Table 2.

Comparison of uncorrected and corrected distance visual acuity of 2 groups

		POD
		1 day	1 week	1 month	3 months	6 months
UDVA (log MAR)	Total	0.05 ± 0.13	-0.01 ± 0.09	-0.03 ± 0.08	-0.05 ± 0.09	-0.05 ± 0.09
	Group A	0.04 ± 0.12	-0.03 ± 0.09	-0.04 ± 0.09	-0.07 ± 0.09	-0.07 ± 0.09
	Group B	0.06 ± 0.14	-0.01 ± 0.09	-0.02 ± 0.08	-0.04 ± 0.08	-0.04 ± 0.08
	p-value	0.171	0.496	0.05	0.328	0.372
CDVA (log MAR)	Total	0.00 ± 0.09	-0.08 ± 0.07	-0.09 ± 0.06	-0.11 ± 0.06	-0.12 ± 0.06
	Group A	-0.01 ± 0.08	-0.08 ± 0.07	-0.10 ± 0.07	-0.11 ± 0.06	-0.12 ± 0.06
	Group B	0.01 ± 0.09	-0.07 ± 0.07	-0.09 ± 0.06	-0.11 ± 0.06	-0.12 ± 0.06
	p-value	0.711	0.134	0.854	0.17	0.075

Values are presented as mean ± SD; Group A: mild to moderate myopia (<-6.0 D, n = 109), Group B: high myopia (>-6.0 D, n = 223). UDVA = uncorrected distance visual acuity; CDVA = corrected distance visual acuity; POD = postoperative day.

Table 3.

Comparison of error in spherical equivalent refraction of 2 groups

	POD
	1 week	1 month	3 months	6 months
Total	-0.20 ± 0.40	-0.21 ± 0.40	-0.21 ± 0.39	-0.21 ± 0.37
Group A	-0.04 ± 0.35	-0.04 ± 0.34	-0.05 ± 0.33	-0.04 ± 0.29
Group B	-0.29 ± 0.40	-0.29 ± 0.40	-0.28 ± 0.39	-0.30 ± 0.37
p-value	0.171	0.39	0.293	0.062

Values are presented as mean ± SD; Group A: mild to moderate myopia (<-6.0 D, n = 109), Group B: high myopia (>-6.0 D, n = 223). POD = postoperative day.

Table 4.

Comparison of efficacy index and safety index of 2 groups

		POD
		3 months	6 months
Efficacy index	Total	1.0 ± 0.19	1.0 ± 0.18
	Group A	1.02 ± 0.20	1.02 ± 0.19
	Group B	0.99 ± 0.18	0.99 ± 0.18
	p-value	0.071	0.09
Safety index	Total	1.12 ± 0.16	1.15 ± 0.16
	Group A	1.13 ± 0.15	1.16 ± 0.16
	Group B	1.12 ± 0.16	1.14 ± 0.16
	p-value	0.98	0.695

Values are presented as mean ± SD; Group A: mild to moderate myopia (<-6.0 D, n = 109), Group B: high myopia (>-6.0 D, n = 223).

POD = postoperative day.

TOOLS

Similar articles