Comparison of higher-order aberration and optical quality after Epi-LASIK and LASIK for myopia.
BACKGROUND
Epipolis laser in keratomileusis (Epi-LASIK) and laser in situ keratomileusis (LASIK) are two main surgical techniques for myopia in refractive surgery at present. However, the visual outcome and optical quality after the two procedures are not clear. We conducted the current prospective study to compare ocular higher-order aberrations and evaluate optical quality after Epi-LASIK and LASIK.


METHODS
Sixty-two eyes were included. Thirty-two eyes were treated using Epi-LASIK and thirty eyes using LASIK. Best-corrected visual acuity, uncorrected visual acuity, manifest refraction, and wavefront aberrations were measured and analyzed preoperatively and 4-6 months postoperatively. Wavefront aberrations were measured by Wavescan (VISX, Santa Clara, CA, USA) using a Hartmann-Shack sensor.


RESULTS
The mean changes in RMS for the 5th order (S(5)) were 0.022 ± 0.009 µm and 0.050 ± 0.010 µm, which was significantly smaller in the Epi-LASIK group than in the LASIK group for a 6-mm pupil (P = 0.048, analysis of covariance). The mean changes in C (5) (-1) and C (5) (5) were significantly smaller in the Epi-LASIK group than in the LASIK group at both 3-mm and 6-mm pupil sizes (P = 0.027, 0.045 and 0.024, 0.027, analysis of covariance). Also, the changes in the contribution of coma-like and spherical-like aberration at 6-mm pupil size were statistically significantly different after both procedures (P = 0.000, randomized block design analysis of covariance).


CONCLUSIONS
Both Epi-LASIK and LASIK show their own characteristics in increased higher-order aberration at smaller and larger pupil sizes, and may create different effects on optical quality for photopic (smaller pupil) and scotopic conditions (larger pupil). We speculate that the visual performance in the Epi-LASIK group may be better than in the LASIK group for the larger pupil size.
Yang
Xiaoyan
X
Tianjin Eye Hospital, Clinical College of Ophthalmology, Tianjin Medical University, No 4, Gansu Rd, Heping District, Tianjin, 300020, China.
Wang
Yan
Y
Zhao
Kanxing
K
Fang
Lihua
L
D057128:Aberrometry; D000293:Adolescent; D000328:Adult; D003315:Cornea / Q000503:physiopathology*; D057108:Corneal Wavefront Aberration / Q000175:diagnosis / Q000503:physiopathology*; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult
J Refract Surg. 1998 May-Jun;14(3):312-7
9641422
J Refract Surg. 2001 Sep-Oct;17(5):S578-83
11583234
J Cataract Refract Surg. 1998 Feb;24(2):190-5
9530593
Br J Ophthalmol. 1997 Feb;81(2):136-40
9059248
Am J Ophthalmol. 1999 Jan;127(1):1-7
9932992
Am J Ophthalmol. 2003 Aug;136(2):327-37
12888057
Curr Opin Ophthalmol. 2006 Aug;17(4):389-93
16900033
J Refract Surg. 2006 Sep;22(7):656-64
16995547
J Refract Surg. 2002 Sep-Oct;18(5):S652-60
12361175
Am J Ophthalmol. 2005 Jan;139(1):168-78
15652843
J Opt Soc Am A Opt Image Sci Vis. 1997 Nov;14(11):2873-83
9379245
J Refract Surg. 2008 Jan;24(1):S90-6
18269157
Curr Opin Ophthalmol. 2003 Aug;14(4):207-12
12888719
Korean J Ophthalmol. 2007 Sep;21(3):131-6
17804916
J Cataract Refract Surg. 2005 May;31(5):879-85
15975451
J Refract Surg. 2007 Nov;23(9):880-7
18041240
Curr Opin Ophthalmol. 2008 Jul;19(4):330-4
18545017
J Cataract Refract Surg. 2006 May;32(5):779-84
16765794
J Cataract Refract Surg. 2002 Dec;28(12):2109-16
12498844
Ophthalmology. 2004 Mar;111(3):447-53
15019317
Arch Ophthalmol. 2005 Jun;123(6):741-56
15955975
J Refract Surg. 2002 Sep-Oct;18(5):S579-83
12361161
J Refract Surg. 2006 Jun;22(6):589-95
16805123
Ophthalmology. 2000 May;107(5):925-33
10811085
Ophthalmology. 2002 Jan;109(1):175-87
11772601
J Opt Soc Am A Opt Image Sci Vis. 2002 Oct;19(10):1937-45
12365613
Chin Med J (Engl). 2007 Feb 20;120(4):269-73
17374275
J Refract Surg. 2005 Nov-Dec;21(6):734-41
16331843
Indian J Ophthalmol. 2002 Dec;50(4):265-82
12532491
Surv Ophthalmol. 2002 Nov-Dec;47(6):533-46
12504738
J Refract Surg. 2002 Sep-Oct;18(5):S556-62
12361157
IEEE Trans Biomed Eng. 2001 Jan;48(1):87-95
11235595
J Cataract Refract Surg. 2002 Oct;28(10):1737-41
12388021
J Refract Surg. 2003 Mar-Apr;19(2 Suppl):S270-4
12699188