This study evaluated 152 eyes of 105 patients that underwent advanced surface ablation (LASEK or Epi-LASEK) to treat extreme refractive errors. The authors found that 72% of eyes achieved 3-month postoperative uncorrected visual acuity equal or better than preoperative best corrected visual acuity, and this was maintained for at least one year. However, extremely hyperopic eyes were at greater risk of losing best corrected visual acuity postoperatively. The study demonstrates that advanced surface ablation can safely and effectively treat extreme prescriptions when combined with adjunctive treatments to prevent scarring, but further research is needed on outcomes for extremely hyperopic eyes.

1. Emil W. Chynn, MD
Sze H. Wong
Dorina Jaubelli
The authors have no financial interest LASEK or Epi-LASEK to treat extreme
in the subject matter of this poster. refractive errors
is not FDA-approved.

2. LASIK is not recommended for high
prescriptions because of compromised
visual outcomes1
Stromal bed thickness >250 microns to
avoid iatrogenic keratectasia2
PRK is prone to scarring for extreme
prescriptions3
Advanced Surface Ablation (LASEK/Epi-

3. To determine whether extreme prescriptions
may be safely and effectively treated with
Advanced Surface Ablation (ASA)

4. Adjunctive treatment to prevent scarring:
• Mitomycin C (MMC) 0.01% intraop
• Oral steroids: 1-3 wks postop
• Topical steroids: 2-6 mo postop
• Vitamin C: 2-6 mo postop
• UV protection: 3-12 mo postop

5. n = 105 Patients (187 Eyes)
Male 51%
Female 49 %
Age (mean ± SD [range]) 32 ± 9 [19 – 66]
Eyes With Extreme Myopia (SE ≥ -9) 78 %
Eyes With Extreme Hyperopia (SE ≥ +6) 7%
Eyes With Extreme Astigmatism (cyl ≥ -3) 29 %
LASEK Eyes 83 %
Epi-LASEK Eyes 17 %
WaveFront Eyes 55 %
Rx Range (SE) -22.63 to +7.50
Preop Corneal Thickness (mean ± SD) 554 ± 38 µm
Ablation Thickness (mean ± SD) 126 ± 36 µm
Postop Corneal Thickness (mean ± SD) 428 ± 53 µm

6. 20/50 =
4
error bar = standard error
20/40 =3
n = 152
UCVA
20/32 =2
Line n = 134 n = 70
Number n = 143 n = 94
20/25 =
1
0
20/20 =
0 1 2 3 4 5 6 7 8 9 10 11 12
1 line = 0.1 logMAR 4 Mo. Postop

7. Postop 1 Mo. 2 Mo. 3 Mo. 6 Mo. 12 Mo.
(n = 152) (n = 134) (n = 143) (n = 94) (n = 70)
Lines
Gained ± 19.21 ± 0.78 19.64 ± 19.83± 19.49 ± 18.55 ±
Standard 0.87 0.84 1.01 1.19
Error
% Eyes
Postop 98 97 97 95 97
UCVA ≥
Preop UCVA
% Eyes
Postop 97 96 97 95 94
UCVA
>Preop
UCVA
1 line = 0.1 logMAR
CF% 20/2000, HM = 20/20,000 4
= Eyes
Postop 1 1 0 0 3

8. 2.0
error bar = standard error
1.5
n = 152
1.0
Postop UCVA
Minus
0.5 n = 134
Preop BCVA n = 70
(line difference) n = 143 n = 94
0.0
0 1 2 3 4 5 6 7 8 9 10 11 12
-0.5
-1.0
Mo. Postop

9. Postop 1 Mo. 2 Mo. 3 Mo. 6 Mo. 12 Mo.
(n = 152) (n = 134) (n = 143) (n = 94) (n = 70)
% Eyes
Postop 40 58 72 65 69
UCVA ≥
Preop BCVA
% Eyes
Postop 18 28 34 33 35
UCVA
>Preop
BCVA
% Eyes
Postop 22 30 38 32 34
UCVA
=Preop
BCVA

10. Null hypothesis tested with unpaired, two-
tailed, unequal variance t-test. P values
listed below:Mo. 2 Mo.
Postop 1 3 Mo. 6 Mo. 12 Mo.
Male vs. Female 0.414 0.612 0.431 0.849 0.314
Age < 40 vs. ≥ 40 0.664 0.149 0.647 0.909 0.400
Extreme Myopia *0.047 0.076 0.067 0.408 0.400
vs. Extreme
Hyperopia
Extreme 0.801 0.526 0.999 0.057 0.864
Astigmatism vs.
Without
Amblyopia vs. 0.216 0.424 0.718 0.114 0.568
Extremely hyperopic eyes had
Without
significantly worse line gain than extreme

11. 8
6
4
2
Postop UCVA
minus 0 Ablation
Preop BCVA Depth
-2 0 50 100 150 200
(micron
-4 s)
-6
-8
Correlation coefficient = 0.02

12. 8
6
4
2
Postop UCVA
Number
minus 0
of
Preop BCVA
-2 0 500 1,000 Pulses
-4
-6
-8
Correlation coefficient = -0.04

13. 8
6
4
2
Postop UCVA
0 Treatment
minus
Time (s)
Preop BCVA -2 0 100 200 300 400 500
-4
-6
-8
Correlation coefficient = -0.02

14. Of 187 eyes:
8 (4 %) postop haze (tr to 2+)
1 (0.5%) corneal edema
3 (1.5%) scarring
2 (1%) iatrogenic keratoconus

15. Extreme prescriptions may be safely and
effectively treated with advanced surface
ablation when combined with adjunctive
treatments to prevent scarring
72% eyes: 3-mo. postop UCVA ≥ preop
BCVA (maintained for at least one year)
Further studies are needed to determine
whether extremely hyperopic eyes are at
risk for loss of BCVA and how to avoid this
loss

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