Intended Flap Decentration in Hyperopic
Laser in Situ Keratomileusis (Lasik) In Eyes
with off-Centered Corneal Apex
Ayman Lotfy1*, Ayman Mohamed Abdelrahman1
1Department of Ophthalmology, Zagazig University Hospitals, Zagazig, Egypt
Ayman lofty, Department of Ophthalmology, Zagazig University Hospitals, 3rd Ahmad Orabi st, Zagazig, Egypt,
Tel: +201224276447; E-mail:
Received: 12 December, 2016; Accepted: 19 December, 2016; Published: 29 December, 2016
Lotfy A, Abdelrahman AM (2016) Intended Flap Decentration in Hyperopic Laser in Situ Keratomileusis (Lasik) In Eyes
with off-Centered Corneal Apex. Int J Open Access Ophthal 1(1): 3. DOI: 10.15226/2474-9249/1/1/00116
Purpose: To evaluate the efficacy of flap decentration during
Lasik hyperopic correction in eyes with off-centered corneal apex.
Patients and methods: In a prospective study, two groups
of patients with hyperopia randomly allocated to undergo Lasik
hyperopic correction. In group A (22 eyes); the flap was intentionally
decentred during flap creation. In group B (22 eyes) were done
without flap decentration. Complete preoperative and postoperative
ophthalmic examination was done for all patients with determination
of spherical equivalents by cycloplegic refraction, Uncorrected
Visual Acuity (UCVA), Best Corrected Visual Acuity (BCVA) were also
detected. Corneal topography was performed to all patients before
and after the operation.
Results: The mean UCVA improved from 0.4 ± 0.23 to 0.90 ± 0.21
in Group (A) and from 0.5 ± 0.3 to 0.8 ± 0.2 in Group (B) (P value =
0.023), and the mean BCVA, from 0.8 ± 0.2 to 0.97 ± 0.1 and from 0.8
± 0.2 to 0.8 ± 0.2, respectively (P value = 0.01). The mean cycloplegic
spherical equivalent improved from + 3.5 ± 0.5 to + 0.25 ± 0.6 in
Group (A) and from + 3.8 ± 0.6 to +0.75 ± 0.6 in Group (B) (P value =
0.02). The safety index was 1.1 in groups and the efficacy index, 1.01
in Group 1 and 0.98 in Group 2. The enhancement rate was 20.0% and
Conclusion: Flap decentration in hyperopic laser correction
Keywords: Angle kappa; Topography; Decentered; Hyper-metropia
Laser in situ keratomileusis (LASIK) has been described as
a means to correct hyperopia . Excimer laser correction of
hyperopic refractive errors involves the para central removal
of a negative meniscus of stromal tissue to indirectly produce
central steepening of the anterior corneal surface . Many
parameters, such as corneal curvature, optical zone size, and
centration, must be taken into account even in correction of
low grade hyperopia . The complications that limit hyperopic
LASIK correction include decentration and regression, which
can affect the predictability, safety, and efficacy of the treatment . The initial reports of hyperopic LASIK (H-LASIK) showed
mostly unsatisfactory results with considerable regression of the
refractive results and a high incidence of loss of Best Corrected
Visual Acuity (BCVA), primarily caused by small outer zone
ablations . The rapid recovery of Uncorrected Visual Acuity
(UCVA) was attributed to the good centration provided by the
active tracking system of the laser. This was important because
long treatment time in hyperopic corrections can produce severe
rotational malpositions that can produce varying results . The
use of planned off-center ablation to correct hyperopia may help
in achieving better visual acuity than centered ablation .
The aim of this study is to evaluate the efficacy of corneal
flap decentration during hyperopic LASIK in patients with offcentered
Material and methods
Forty four eyes of 22 patients with hyperopia were included
in this study. The eyes were divided randomly into two groups.
In group A (22 eyes); the flap was intentionally decentered
during flap creation. In group B (22 eyes) were done without flap
decentration. Preoperatively, a complete ophthalmic examination
was performed including Uncorrected Visual Acuity (UCVA),
Best Corrected Visual Acuity (BCVA), manifest and cycloplegic
refraction. Spherical error ranged from + 1.00 to + 6.00 diopters,
and refractive cylinder ranged from + 0.50 to + 2.5 D. Slit lamp
biomicroscopy, applanation tonometry, and corneal topography
were performed to all patients. Corneal topography was used to
detect off- centered corneal apex. (Fig. 1). Emmetropia was the
goal in all eyes.
In group (A): Topical anesthesia was used. Flap alignment
marks were placed on the cornea using a marker coated with
methylene blue. A -1LC Moria M2 suction ring was used in all
cases. The ring was positioned on the cornea with a slight medial
decentration; suction was activated and intraocular pressure
was verified to be at least 65mmHg. Moria M2 microkeratome
head 130 was used to create corneal flap. The flap was reflected superiorly, exposing the stromal bed. Allegrtto 400Hz laser
platform (Wave Light, Erlangen Germany) was used for laser
ablation using T-CAT ablation profile to ensure centration of
treatment around corneal apex. 6 mm optical zone was applied
in all cases. Care was taken to ensure that the stromal bed was
dry before and during the ablation and that the undersurface of
the flap was protected from the laser ablation. The interface was
irrigated with a balanced salt solution; the flap was replaced.
Adequate flap position was verified at the slit lamp immediately
In group (B): the hyperopic LASIK correction was done but
without flap decentration. Postoperative, patients were seen 1
day, 1 week, and 1, 3, and 6 months after surgery at which times
UCVA, manifest refraction, BSCVA, corneal topography, and
corneal flap status were determined. For the statistical analysis
of results between the groups, a chi-squared test was used with
the level of significance set at p < 0.05.
Forty four eyes of 22 patients with hyperopia were underwent
hyperopic LASIK correction. The eyes are divided into two
groups; Group (A) of 22 eyes will go operation with intended flap
decentration. Group (B) will go operation without decentration.
In group (A), the preoperative UCVA ranged from 0.5 to 0.1 with
mean of 0.4 ± 0.23 and in group (B) the UCVA ranged from 0.4 to
0.1 with mean of 0.5 ± 0.3 (P value = 0.43 which is insignificant).
The mean BCVA was 0.8 ± 0.2 in group (A) and 0.8 ± 0.4 in group
(B). The mean cycloplegic spherical equivalent was + 3.5 ± 0.5
and + 3.8 ± 0.6 respectively [Table 1]. Postoperatively, the mean
UCVA improved from 0.4 ± 0.23 to 0.90 ± 0.21 in Group (A) and
from 0.5 ± 0.3 to 0.8 ± 0.2 in Group (B) (P value = 0.023), and the
mean BCVA, from 0.8 ± 0.2 to 0.97 ± 0.1 and from 0.8 ± 0.4 to 0.8 ±
0.2, respectively (P value = 0.01). The mean cycloplegic spherical
equivalent improved from + 3.5 ± 0.5 to + 0.25 ± 0.6 in Group (A)
and from + 3.8 ± 0.6 to +0.75 ± 0.6 in Group (B) (P value = 0.02).
[Table 2] [Figure 1-2]. The safety index was 1.1 in both groups
and the efficacy index, 1.01 in Group (A) and 0.98 in Group (B).
The enhancement rate was 20.0% and 18.4%, respectively.
Laser correction of hyperopia involves the removal of
a negative meniscus of stromal tissue that is thicker at the
periphery than at its center. This reshapes the anterior corneal
surface by steepening its curvature [1,8]. The initial reports
of hyperopic LASIK (H-LASIK) showed mostly unsatisfactory
results with considerable regression of the refractive results and
a high incidence of loss of BSCVA [3-9]. In this study, one week
Table 1: Patients data
No. of eyes
0.4 ± 0.23
0.5 ± 0.3
0.8 ± 0.2
0.8 ± 0.4
3.5 ± 0.5
3.8 ± 0.6
Figure 1: Pre-& Post-operative UCVA
Figure 2: Preoperative and Postoperative BCVA
Table 2: Postoperative Data
0.90 ± 0.21
0.8 ± 0.2
0.97 ± 0.1
0.8 ± 0.2
0.25 ± 0.6
+0.75 ± 0.6
after hyperopic LASIK correction, the mean UCVA was 0.9 in
group A which undergone the operation with flap decentration
while it was 0.8 in group B without flap decentration with
significant statistically difference (p= 0.023). The group with
flap decentration showed BCVA postoperatively 0.97 and the
patients of other group had mean postoperative BCVA 0.8 with
high significant difference (p= 0.01).
Zadok et al  on their study on 92 eyes undergone
hyperopic LASIK correction, they divided the patients into 3
groups according to the degree of hyperopia: low hypeopia
(+3.00 D), moderate hypeopia (+3 - +6.00 D) & high hyperopia (≥
+ 6 D). They reported that spherical equivalent postoperatively
was +0.33 in low hyperopic group, +0.21 D in moderate group
& +1.62 D in high group. Carlos and Maria  compared the
results of hyperopic laser in situ keratomileusis (LASIK) with a
5.9 mm optical zone (OZ) to those with smaller zones (4.4 to 5.5
mm). They operated 147 cases with 5.9 mm optical zone and 679
cases with smaller zone. They found that hyperopic LASIK with
a 5.9 mm OZ in eyes with low, moderate and high hyperopia is
more stable, predictable, and safer than hyperopic LASIK with
smaller optical zone.
Williams et al  operated 49 hyperopic eyes with
mean preoperative hyperopia + 3.44 D. They also detect the
preoperative K reading for all patients. They reported loss of
1 or more line of BCVA in 11 patients and they concluded that
an increased incidence of loss of BSCVA and decreased patient
satisfaction was associated with a preoperative K value greater
than 44.0 D in hyperopic LASIK. Fernando et al , in their
retrospective study, evaluated hyperopic LASIK results over 1
year. They divided the patients into 2 groups (Group 1: < +3.50
D. & Group 2 ˃ + 3.60 D). they reported that the mean UCVA
improved from 0.50 to 0.9 in Group 1 and from 0.5 to 0.80 in
Group 2 and the mean BCVA, from 0.8 to 0.93 0.1 and from 0.8 to
0.9 respectively. The mean spherical equivalent improved from +
2.5 ± 0.8 to +0.1 ± 0.5 in Group 1 and from + 4.5 ± 0.6 to +0.4± 0.6
in Group 2. The safety index was 1.1 in groups and the efficacy
index, 1.01 in Group 1 and 0.98 in Group 2.
The results of this study confirm that flap decentration during
hyperopic LASIK correction has a better results with higher
safety and efficacy in patients with off-centered corneal apex.
Authors acknowledge the immense help received from the
scholars whose articles are cited and included in references of
this manuscript. The authors are also grateful to authors / editors
/ publishers of all those articles, journals and books from where
the literature for this article has been reviewed and discussed.
The idea of the work was combined thinking of both authors.
All the cases were operated by the same surgeon (AMA), the data
were collected and evaluated by the corresponding author (AL).
This research received no specific grant from any funding
agency in the public, commercial or not-for-profit sectors. The
authors have no financial interest in the subject of the study and
there is no conflict of interest.
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