Transcript Corneal Epithelial Healing After LASIK Surgery

Category: P5 Refractive
Corneal Epithelial
Healing After
LASIK Surgery
Yousuf Khalifa, MD
Tracie Sponseller, OD
David Bogorad, MD
Introduction
• LASIK flap creation and stromal ablation elicit
healing responses in the corneal epithelium
and stroma
• Physiology of corneal stroma healing after
LASIK surgery has been described
• Corneal epithelial wound healing after LASIK
surgery has not been reported previously to
our knowledge
• Insights into the factors involved in corneal
epithelium healing can be drawn from LASIK
surgery
Methods
• 65 consecutive LASIK surgery patients were included
• LASIK flaps created with the Moria M2
microkeratome, with Moria disposable heads, using
published nomograms
• Alcon Ladarvision 4000 platform used
• Conventional, Custom, Myopic, and Hyperopic
corrections included
• Prednisolone Acetate 1% and Vigamox were
prescribed tid along with Systane qid + prn
• Patients evaluated at postoperative day 1 with
fluorescein staining to assess number of clock hours
healed
Methods
• Patient age, sex, treatment refraction,
microkeratome suction ring and flap
thickness, ablation depth, time of LASIK,
elapsed time from surgery, number of stained
clock hours entered into Excel spreadsheet
• SAS version 9.1 was used for all analyses
and statistical significance was assessed at
the 5% level
Results
Variable
n (%)
Gender
Male
Female
29 (45%)
36 (55%)
Smoker
Yes
No
8 (12%)
57 (88%)
Table 1. Descriptive Statistics for demographic variables
Results
Variable
n
OS
Mean ± SD
OD
Median
(Range)
5 (0, 10)
n
Mean ± SD
65
5.2 ± 3.6
5 (0, 10)
Median (Range)
Clock Hours
Healed
62 5.0 ± 3.5
Ablation Depth,
(microns)
62 73.6 ± 32
72 (28,
167.5)
65
70 ± 33.9
64 (22.9, 158.8)
Sphere
(diopters)
62 -2.2 ± 2.7
-2.5 (-7, 5.4)
65
-2.3 ± 2.5
-2 (-7.5, 5.4)
Cylinder
(diopters)
62 -1.0 ± 0.8
-0.8 (-3.7, 0)
65
-0.9 ± 0.8
-0.6 (-3.4, 0)
Surgery Time
(seconds)
62 85 ± 36.9
81.5 (2, 192)
65
78 ± 35.1
72 (30, 168)
Shots Fired
62 4853.6 ± 206
6.5
4734 (2 048,
11784)
65
4592.8 ± 21 10.8
Table 2. Median and range of continuous variables.
4202 (1591
, 10307)
Results
2
4
Mean + 2SD
-2
0
Mean
-4
Mean - 2SD
0
2
4
6
8
Mean Clock Hours For Each Person
10
A Bland-Altman plot
illustrates that the
majority of the eyes
within each subject
are within the limits of
agreement. Thus, the
measurement of clock
hours is in agreement
for the two eyes within
each subject and that
healing did not differ
between the eyes.
Results
Variable
n
OS
Median
(Range)
OD
Clock Hours Median
Healed
(Range)
Mean ± SD
Suc tion Ring
2
1
0
-1
28
8
24
2
Clock
Hours
Healed
Mean ± SD
4.8 ± 3.7
6 ± 3.3
4.8 ± 3.4
4.0 ± 5.7
p-value
n
5 (0, 10)
6.5 (0, 10)
5 (0, 10)
4 (0, 8)
0.797
25
10
28
2
5.4
5.9
4.9
4.5
± 3.8
± 4.1
± 3.4
± 0.7
5 (0, 10)
7 (0, 10)
5 (0, 10)
4.5 (4, 5)
0.858
Ring Diameter
7.5
8
37
25
4.9 ± 3.7
5.0 ± 3.4
5 (0, 10)
5 (0, 10)
0.818
36
29
5.6 ± 3.8
4.8 ± 3.3
6 (0, 10)
5 (0, 10)
0.402
Blade
90
130
26
36
5.5 ± 3.7
4.5 ± 3.4
6 (0, 10)
5 (0, 10)
0.159
26
39
5.9 ± 4.0
4.7 ± 3.2
7 (0, 10)
5 (0, 10)
0.189
Number of
Surgery
Interruptions
0
1
2
54
7
1
5.0 ± 3.4
5.1 ± 4.6
2.0 ± 0
5 (0, 10)
7 (0, 10)
2 (2, 2)
0.745
61
4
0
5.1 ± 3.5
7.3± 4.2
-
5 (0, 10)
9 (1, 10)
-
0.276
Gender
Male
Female
27
35
5.1 ± 3.5
4.9 ± 3.6
6 (0, 10)
4 (0, 10)
0.892
29
36
5.4 ± 3.3
5.0 ± 3.7
5 (0, 10)
5 (0, 10)
0.548
Smoker
Status
Smoker
Nonsmoker
8
54
3.6 ± 3.1
5.1 ± 3.6
3 (0, 8)
5 (0, 10)
0.220
8
57
5.1 ± 4.1
5.2 ± 3.5
5.5 (0, 9)
5 (0, 10)
0.772
Sphere
Sign
+
-
8
54
4.1 ± 3.2
5.1 ± 3.6
4.5 (0, 8)
5 (0, 10)
0.372
8
57
4.1 ± 3.3
5.4 ± 3.6
3.5 (0, 9)
5 (0, 10)
0.328
Table 3. Wilcoxon-Mann-Whitney or Kruska l-Wallis resu lts and median and range of
clock hours re-epithelial for eac h group.
p-value
Results
Table 4. Overall p-value for ranked regression.
Variable
p-value
OS
OD
Ablation Depth
0.625
0.197
Shots Fired
0.921
0.270
Surgery Time
0.818
0.278
SPK (superficial punctate
0.116
0.168
kerat opathy)
Age
0.087
0.285
Elapsed Time
0.025*
0.001*
*Significant at the 0.05 level.
Results
Table 5. Spearman correlation with clock hours.
Variable
Correlation (p-value)
OS
OD
VA
-0.386(0.002)
Elapsed Time
0.284 (0.025)
0.389 (0.001)
Age
-0.219(0.087)
-0.135(0.285)
Discussion
• LASIK surgery is an ideal model to study human
epithelial wound healing
– Our results show that suction ring size, flap thickness,
ablation depth have no correlation with epithelial healing
– Fluorescein staining is a simple, safe, clinically accepted
means of assessing epithelial integrity
– Our study lays the foundation for future studies looking at
factors that influence epithelial healing
• Postoperative Day 1 is an excellent window to assess
the epithelial healing because of the range of healed
clock hours. In our study the elapsed time from
surgery ranged from 16 to 26 hours.
Discussion
• OD and OS healing rates are consistent
within each patient
– Using the same blade on the OS after the OD
does not affect epithelial healing
• Between 16 and 26 hours after LASIK
surgery the epithelial healing varies; but the
further out from surgery, the more likely to
have more healed clock hours
• Age did not closely correlate
• Smoking status did not correlate
– This study is likely underpowered to determine the
effects of smoking