Comparing Visual Outcomes After FemtoLasik and Implantable Collamer Lens in Treatment of Myopia
Phase: NA
Conditions: Myopia, Moderate
Sponsor: Walid Osama Abdel Rahman Nour El Din

 
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Comparing Visual Outcomes after FemtoLASIK and Implantable 
Collamer Lens in Treatment of Myopia 
 
Thesis 
Submitted in partial fulfillment of the requirements for the MD degree in 
Ophthalmology 
By 
Walid Osama Abdel Rahman Nour El Din 
MSc in Ophthalmology, Faculty of Medicine, Ain Shams University, 2019 
MBBCh, Faculty of Medicine, Cairo University, 2012 
 
Under supervision of 
Dr. Omar Mohamed Sayed Saeed 
Assistant Professor of Ophthalmology 
Faculty of Medicine, Fayoum University 
Dr. Mohamed AbdAllah Ahmed Mahmoud 
Lecturer of Ophthalmology 
Faculty of Medicine, Fayoum University 
 
 
Faculty of Medicine, Fayoum University, 
Cairo, Egypt 
11/12/2021 

 
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INTRODUCTION 
 
Myopia known as “short sightedness” causes blurring of vision for distant 
objects but clearer for near objects. In myopic eyes, the light comes to a focus point 
before it reaches the retina. When moving closer to an object, this changes the focusing 
of the light and the object is then in focus on the retina and so looks clearer. Myopia 
depends on the length of the globe, the corneal steepness, and the lens power. 
Classification of myopia: 
• Mild myopia: power up to - 4.00 diopters (D) 
• Moderate myopia: -4.00D to -8.00D 
• High myopia: > -8.00D 
ICL implantation can correct myopia, hyperopia, or astigmatism, with clinical 
and visual results as good as or better than laser procedures. Patients who are not 
suitable candidates for corneal reshaping procedures, and in whom optical correction 
with spectacles or contact lenses is either challenging or have poor results, can benefit 
from ICL surgery. 
One of the problems for LASIK application for myopic patients is the risk of 
post-LASIK ectasia which is believed to be reduced using femto LASIK and the ability 
of creation of smaller flap thickness. Less high order aberrations are induced with 
femto LASIK compared to the conventional approach. Results in terms of contrast 
sensitivity, especially in high spatial frequencies, are better with femto LASIK 
compared to the conventional method. 
This study evaluates the effect of each modality treatment on the visual 
outcomes in treatment moderate myopic patients. (1) 
Phakic intraocular lenses (PIOLs) are generally accepted as an alternative 
treatment for ametropic correction among different types of refractive correction. 
Rapid visual recovery, high efficacy, predictability and stability of visual quality, 
preservation of accommodation, and reversibility are several privileges that have been 
attributed to PIOL implantation. (2, 3) 
 
 
 
 

 
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The Visian Implantable Collamer Lens (ICL; STAAR Surgical Co, Monrovia, 
California) is approved by the United States Food and Drug Administration (FDA) for 
the treatment of moderate to severe myopia. The lens material, trade-named Collamer, 
is a hydrophilic collagen-polymer combination with a water content of 34% and a 
refractive index of 1.45. (2)  
Recently, a new ICL (V4c) , with a 360 μm central hole that allows for the 
natural flow of aqueous humor without the need for a peripheral iridotomy, which may 
reduce the risk of anterior capsular opacification and cataract formation comparing to 
the old forms of ICL.(4,5) Previous studies have shown that the pupil constriction in 
response to light can affect the vault, eventually causing the ICL to move posteriorly 
towards the crystalline lens, leading to a significant decrease in central vault under 
photopic conditions.(4,6) 
Femtosecond (FS) laser is an infrared laser with a wavelength of 1053 nm. It 
works by producing photo-disruption or photoionization of the optically transparent 
tissue such as the cornea. (1) Application of FS results in the generation of a rapidly 
expanding cloud of free electrons and ionized molecules. The acoustic shock wave 
generated results in disruption of the treated tissue. (7) 
FS laser has pulse duration ranging 10 to 15 seconds. Reducing the pulse 
duration reduces the amount of collateral tissue damage which makes FS laser safe to 
be used in corneal surgeries. (8, 9) 
The Wave Scan Wave Print System (Visx, Inc.) is a diagnostic instrument 
designed to measure and display refractive errors and wave front aberrations of the eye 
using a Hartmann-Shack wave front sensor. A small spot of laser light is projected onto 
the retina and reflects back through the pupil. The light exiting from the eye is imaged 
by a lens let array, and the array of spot images is captured by a video sensor. The 
location of each spot gathered from the video sensor is then compared to the theoretical 
ideal locations, and the eye’s wave front aberrations are computed. The measurements 
with this device are centered on the center of the entrance pupil and taken without pupil 
dilation. (10) 
 
 
 
 
 

 
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Contrast sensitivity is defined as the inverse of the contrast value at threshold. 
Contrast sensitivity is plotted on a chart in which the x axis is the spatial frequency, 
and the y axis is contrast sensitivity in log scale. Spatial frequency is specified in cycles 
per degree (cpd), which corresponds to the spatial frequency of the sine wave grating 
in terms of size, using cycles per degree of visual angle as the unit. Maximal contrast 
sensitivity function is at 3 to 6 cpd. The curve of contrast sensitivity is bell shaped. At 
the high frequency end, where contrast sensitivity is lowest, 100% contrast is needed, 
it corresponds to visual acuity. (11) 
 
 
 

 
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AIM OF THE WORK 
 
This study aims to compare visual outcomes after Femto LASIK and 
implantable collamer lens in treatment of moderate myopia. 
 
 
 

 
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SUBJECTS & METHODS 
 
• Type of Study: Prospective observational study 
 
• Study Setting: Magrabi Eye Hospital, Cairo, Egypt 
 
• Study Period: 24 months. The patient will be assessed on interval: 
preoperatively, 1 month, 3 months and 6 months postoperatively. 
 
• Study Population: 
o Inclusion Criteria: 
➢ Moderate myopia (-4D to -8D) 
➢ Age >18 years 
➢ Clear optical media 
➢ No ocular pathology 
o Exclusion Criteria: 
➢ Mild (<-4D) or high (>-8D) myopia, hyperopia 
➢ Patients with media opacity 
➢ Patients with associated ocular pathology 
➢ Patients with corneal topography not fitting to either treatment 
modalities 
• Sampling Method: Convenience non-random sampling technique will be 
followed 
 
 

 
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• Sample Size: 120 eyes will be included in the study, and they will be divided 
into four groups: 
➢ Group 1: includes 60 eyes undergoing ICL surgery 
Divided into two subgroups: 
• Group 1A: includes patients with simple myopia 
• Group 1B: includes patients with compound myopic 
astigmatism 
➢ Group 2: includes 60 eyes undergoing femtoLASIK surgery 
Divided into two subgroups: 
• Group 2A: includes patients with simple myopia 
• Group 2B: includes patients with compound myopic 
astigmatism 
 
• Ethical Considerations: This study will be conducted after the approval of the 
institutional ethical committee and after obtaining an informed written consent 
from every patient 
 
• Study Tools:  
➢ Slit Lamp Biomicroscopy 
➢ Pentacam for full corneal topography profile (Oculus) 
➢ Wave scan J&J vision Visx for assessment of aberrations 
➢ PeliRobson Chart for testing of contrast sensitivity 
 
• Study Procedure: Patients will be diagnosed according to: 
➢ Full detailed history 
➢ Complete clinical ophthalmological examination including visual 
acuity assessment with best correction, anterior segment 
examination, IOP measurement, fundus examination, cycloplegic 
refraction and contrast sensitivity testing 
➢ Investigations: corneal topography, aberrations screening 
➢ Post-operative follow up including visual acuity assessment with 
best correction, aberrations screening and contrast sensitivity 
testing on interval 1 month, 3 months and 6 months postoperatively 

 
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Statistical Analysis & Package: The collected data will be revised, coded, tabulated, 
and introduced to a PC using statistical package for social sciences (IBM SPSS 20.0). 
Data will be presented and suitable analysis will be done according to the type of 
data obtained for each parameter. 
o Descriptive Statistics: 
➢ Mean, Standard deviation (±SD) and range for parametric 
numerical data, while Median and Interquartile range (IQR) for 
non-parametric data 
➢ Frequency and percentage of non-numerical data 
o Analytical Statistics: 
➢ Pearson Correlation Coefficient (r): Correlation was used as a 
measure of the strength of a linear association between two 
quantitative variables. The Pearson correlation coefficient, r, can 
take a range of values from +1 to -1. A value of 0 indicates that 
there is no association between the two variables. A value greater 
than 0 indicates a positive association; that is, as the value of one 
variable increases, so does the value of the other variable. A value 
less than 0 indicates a negative association; that is, as the value of 
one variable increases, the value of the other variable decreases 
➢ P-value: Level of significance:  
▪ P>0.05: Non significant (NS)  
▪ P<0.05: Significant (S) 
▪ P<0.01: Highly significant (HS) 
 
 

 
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REFERENCES 
1. Chung SH, Mazur E. Surgical applications of femtosecond lasers. Journal of 
biophotonics. 2009; 2(10):557-72. 
2. Lovisolo CF, Reinstein DZ. Phakic intraocular lenses. Survey of 
ophthalmology. 2005; 50(6):549-87. 
3. Sanders DR, Doney K, Poco M. United States Food and Drug Administration 
clinical trial of the Implantable Collamer Lens (ICL) for moderate to high 
myopia: three-year follow-up. 
4. Lee H, Kang SY, Seo KY, Chung B, Choi JY, Kim KS, et al. Dynamic vaulting 
changes in V4c versus V4 posterior chamber phakic lenses under differing 
lighting conditions. Am J Ophthalmol. 2014; 158(6):1199-204.e1. 
5. Du C, Wang J, Wang X, Dong Y, Gu Y, Shen Y. Ultrasound biomicroscopy of 
anterior segment accommodative changes with posterior chamber phakic 
intraocular lens in high myopia. Ophthalmology. 2012; 119(1):99-105. 
6. Kamiya K, Shimizu K, Hikita F, Komatsu M. Posterior chamber toric phakic 
intraocular lens implantation for high myopic astigmatism in eyes with pellucid 
marginal degeneration. Journal of cataract and refractive surgery. 2010; 
36(1):164-6. 
7. Soong HK, Malta JB. Femtosecond lasers in ophthalmology. Am J Ophthalmol. 
2009; 147(2):189-97.e2. 
8. Stern D, Schoenlein RW, Puliafito CA, Dobi ET, Birngruber R, Fujimoto JG. 
Corneal ablation by nanosecond, picosecond, and femtosecond lasers at 532 and 
625 nm. Archives of ophthalmology (Chicago, Ill: 1960). 1989; 107(4):587-92. 
9. Ratkay-Traub I, Ferincz IE, Juhasz T, Kurtz RM, Krueger RR. First clinical 
results with the femtosecond neodynium-glass laser in refractive surgery. 
Journal of refractive surgery (Thorofare, NJ: 1995). 2003; 19(2):94- 103. 
10. Wang L, Koch DD. Ocular higher-order aberrations in individuals screened for 
refractive surgery. 2003. Cullen Eye Institute, Baylor College of Medicine, 
Department of Ophthalmology, Houston, Texas, USA. Available from: 
https://www.sciencedirect.com/science/article/abs/pii/S0886335003006436. 
11. Owsley C, Sloane ME. Contrast sensitivity, acuity, and the perception of ‘real-
world’ targets. Br J Ophthalmol 1987; 71:791-6.