Contoura vs Wavefront Optimized Ablation
Study Details
Study Description
Brief Summary
To evaluate the efficacy, safety and accuracy of Contoura topography-guided LASIK & PRK in comparison to Wavefront optimized LASIK & PRK in virgin eyes with astigmatism.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
|
Detailed Description
In Upper Egypt, The second principal cause of blindness was uncorrected refractive errors accounting for 16% of sample population. It was reported that astigmatism (defined as cylinder power > 0.5 D) was the most common refractive errors in children and adults followed by hyperopia and myopia.
Laser vision correction has been established over the last 2 decades as a safe and effective intervention to treat refractive errors, being one of the main techniques practiced globally.
However, many subjects after LASIK had uncorrected distance visual acuity (UDVA) greater than 1.0, they complain about poor night vision, glare, and double vision. As studies have shown that every 1° deviation of the astigmatic axis could result in loss of correction of 3.3%. Even residual astigmatism less than 0.50D could have an actual impact on visual quality.
Excimer laser ablation used in the correction of refracted errors especially astigmatism may reduce quality of vision, and that is attributed to the induced optical aberrations. The most prevalent of these optical aberrations is the spherical aberration.
Among multiple sophisticated profiles that developed to optimize visual outcomes, wavefront optimized profile which compensate for corneal curvature to reduce spherical aberration.
The topographic guided profiles which consider the shape of the anterior corneal surface. Contoura topography guided ablation corrects astigmatic power and axis to create a more uniform, aberration-free cornea.
Treating astigmatism can be challenging as the conventional patterns of Excimer laser treatment of astigmatism is known to be less predictable than that of spherical refractive errors.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Group A Contoura topography-guided LASIK |
Procedure: Laser assisted in-situ keratomileusis
Laser-Assisted In Situ Keratomileusis is a procedure that permanently changes the shape of the cornea using an excimer laser and the mechanical microkeratome (a blade device) used to cut a flap in the cornea.
Other Names:
|
| Group B Contoura topography-guided PRK |
Procedure: Photorefractive keratectomy
Photorefractive keratectomy is a laser refractive procedure used to ablate the corneal stroma to correct refractive errors without cutting flap
Other Names:
|
| Group C Wavefront-optimized LASIK |
Procedure: Laser assisted in-situ keratomileusis
Laser-Assisted In Situ Keratomileusis is a procedure that permanently changes the shape of the cornea using an excimer laser and the mechanical microkeratome (a blade device) used to cut a flap in the cornea.
Other Names:
|
| Group D Wavefront-optimized PRK |
Procedure: Photorefractive keratectomy
Photorefractive keratectomy is a laser refractive procedure used to ablate the corneal stroma to correct refractive errors without cutting flap
Other Names:
|
Outcome Measures
Primary Outcome Measures
- Change in Postoperative UDVA compared to preoperative CDVA (in LogMAR) [3 month]
UCVA 3 month after surgery compared to baseline preoperative CDVA
- Number of lines of preoperative CDVA compared to postoperative [3 month]
Change in lines of CDVA from baseline preoperative to 3 month postoperative (in LogMAR)
- Amount of Residual Astigmatism postoperatively (in Diopters) [3 month]
residual astigmatism 3 month postoperatively
- Postoperative mean spherical equivalent MSE compared to Preoperative MSE (in Diopters) [3 month]
changes in mean spherical equivalent baseline preoperative to 3 month postoperative
Secondary Outcome Measures
- Change in Contrast sensitivity test [3 month]
- Amount of High order aberrations [3 month]
(Spherical aberration, trefoil, vertical & horizontal coma)
Eligibility Criteria
Criteria
Inclusion Criteria:
-
Astigmatism (up to 5.0 diopters) or less.
-
Central corneal thickness (CCT) of 500 microns or more
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Estimated Residual stromal bed thickness (RSB) of 280 microns or more
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Subject has provided written informed consent
Exclusion Criteria:
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Keratoconus
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Abnormal topography
-
previous ocular trauma or eye surgery
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pre-existing diseases of the vitreous, macula, or optic nerve that can affect visual outcome
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patients with uveitis and anterior segment pathology
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patients with corneal pathology or Severe dry eye
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pregnancy or breast-feeding females
-
uncontrolled vascular or autoimmune disease
Contacts and Locations
Locations
No locations specified.Sponsors and Collaborators
- Hebatallah MT Abdelmoniem
Investigators
- Study Chair: Mohamed A. Sayed, Ass. Prof., Assiut University
Study Documents (Full-Text)
None provided.More Information
Publications
- Bailey MD, Zadnik K. Outcomes of LASIK for myopia with FDA-approved lasers. Cornea. 2007 Apr;26(3):246-54. doi: 10.1097/ICO.0b013e318033dbf0.
- Canones-Zafra R, Katsanos A, Garcia-Gonzalez M, Gros-Otero J, Teus MA. Femtosecond LASIK for the correction of low and high myopic astigmatism. Int Ophthalmol. 2022 Jan;42(1):73-80. doi: 10.1007/s10792-021-02001-x. Epub 2021 Aug 9.
- Gatinel D, Malet J, Hoang-Xuan T, Azar DT. Analysis of customized corneal ablations: theoretical limitations of increasing negative asphericity. Invest Ophthalmol Vis Sci. 2002 Apr;43(4):941-8.
- Hashemi H, Fotouhi A, Yekta A, Pakzad R, Ostadimoghaddam H, Khabazkhoob M. Global and regional estimates of prevalence of refractive errors: Systematic review and meta-analysis. J Curr Ophthalmol. 2017 Sep 27;30(1):3-22. doi: 10.1016/j.joco.2017.08.009. eCollection 2018 Mar.
- Kanellopoulos AJ. Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK. Clin Ophthalmol. 2016 Nov 3;10:2213-2221. doi: 10.2147/OPTH.S122345. eCollection 2016.
- Lin Y, Su HJ, Yuan MZ, Zhang Y. Vector analysis of Contoura Vision for the correction of myopia and myopic astigmatism. Int J Ophthalmol. 2022 Jun 18;15(6):983-989. doi: 10.18240/ijo.2022.06.17. eCollection 2022.
- Lukenda A, Martinovic ZK, Kalauz M. Excimer laser correction of hyperopia, hyperopic and mixed astigmatism: past, present, and future. Acta Clin Croat. 2012 Jun;51(2):299-304.
- Motwani M. The use of WaveLight(R) Contoura to create a uniform cornea: the LYRA Protocol. Part 3: the results of 50 treated eyes. Clin Ophthalmol. 2017 May 16;11:915-921. doi: 10.2147/OPTH.S133841. eCollection 2017.
- Mousa A, Courtright P, Kazanjian A, Bassett K. Prevalence of visual impairment and blindness in Upper Egypt: a gender-based perspective. Ophthalmic Epidemiol. 2014 Jun;21(3):190-6. doi: 10.3109/09286586.2014.906629. Epub 2014 Apr 18.
- Villegas EA, Alcon E, Artal P. Minimum amount of astigmatism that should be corrected. J Cataract Refract Surg. 2014 Jan;40(1):13-9. doi: 10.1016/j.jcrs.2013.09.010.
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