Corneal Cross-linking and Refractive Surface Ablation in Patients With Asymmetric Corneas

Surgical Procedure, Unspecified Clinical Trial

Official title:

Two Years Follow up of Corneal Cor Cross-linking and Refractive Surface Ablation in Patients With Asymmetric Corneal Topography

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02943967
• Other study ID #: 2088/88
• Status: Completed
• Phase: N/A
• First received: October 21, 2016
• Last updated: October 24, 2016
• Start date: January 2010
• Est. completion date: January 2014

Study information

• Verified date: October 2016
• Source: Federal University of São Paulo
• Contact: n/a
• Is FDA regulated: No
• Health authority: Brazil: National Committee of Ethics in Research
• Study type: Interventional

Clinical Trial Summary

The purpose of this study is to evaluate safety and efficacy of corneal cross-linking and photorefractive keratectomy for refractive correction in patients with bilateral asymmetric topography.

Description:

Corneal cross-linking (CXL) by the photosensitizer, riboflavin (vitamin B2), and ultraviolet A (UVA) light increases corneal rigidity and has been described as an effective method for stabilizing the cornea in patients with progressive keratoconus. The photochemical reaction in this procedure causes the collagen to form additional covalent connections between its fibers, which stabilizes the stromal collagen fibers, improving the collagen's structure and the cornea rigidity. It is a relatively safe procedure with low rates of complications Photorefractive keratectomy (PRK) it is a traditional technique for refractive surgery. In cases of irregular corneas or re-operation normally the favorite ablation profile chosen is the guided surgery, topography guided or wavefront guided, showing better results. This technique is also relatively safe procedure with low rates of complications. One of the most unwanted complications of this surgery and also rare is corneal ectasia.

Combining PRK and CXL is already done in patients with keratoconus and suspected keratoconus.

This combined procedure uses the principle that CXL stiffen the cornea making it possible to reduce corneal thickness with PRK without weakening corneal strength. Literature show better results, in keratoconus, with simultaneous procedures. Guedj et al performed PRK in keratoconus suspects and within 5 years he did not found any corneal ectasia.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 44
• Est. completion date: January 2014
• Est. primary completion date: January 2014
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 23 Years to 51 Years

Eligibility

Inclusion Criteria:

• bilateral asymmetric topography with inferior steepening

• corneal thickness of 440 micra at the thinnest point

• inferior-to-superior index (I-S) between 1.0D and 1.4D

• maximum keratometric steepness < 47.00D

• stable refraction more than 1 year.

Exclusion Criteria:

• forme fruste keratoconus and keratoconus

• previous eye surgery

• previous eye trauma

• confirmed pregnancy

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Surgical Procedure, Unspecified

Intervention

Procedure:
• CXL + PRK group
Corneal cross-linking with subsequent photorefractive keratotomy after 6 months was performed in one eye
• PRK group
Photorefractive keratotomy alone was performed in contra lateral eyes

Locations

Country	Name	City	State
Brazil	Federal University of São Paulo	Sao Paulo

Sponsors (1)

Lead Sponsor	Collaborator
Federal University of São Paulo

Country where clinical trial is conducted

Brazil, 

References & Publications (13)

Abib FC, Holzchuh R, Schaefer A, Schaefer T, Godois R. The endothelial sample size analysis in corneal specular microscopy clinical examinations. Cornea. 2012 May;31(5):546-50. doi: 10.1097/ICO.0b013e3181cc7961. — View Citation

Camellin M, Guidotti JM, Arba Mosquera S. Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus. J Optom. 2016 Mar 21. pii: S1888-4296(16)00008-X. doi: 10.1016/j.optom.2016.02.001. [Epub ahead of print] — View Citation

Carones F, Vigo L, Scandola E, Vacchini L. Evaluation of the prophylactic use of mitomycin-C to inhibit haze formation after photorefractive keratectomy. J Cataract Refract Surg. 2002 Dec;28(12):2088-95. — View Citation

Cheema AS, Mozayan A, Channa P. Corneal collagen crosslinking in refractive surgery. Curr Opin Ophthalmol. 2012 Jul;23(4):251-6. doi: 10.1097/ICU.0b013e3283543cbd. Review. — View Citation

Guedj M, Saad A, Audureau E, Gatinel D. Photorefractive keratectomy in patients with suspected keratoconus: five-year follow-up. J Cataract Refract Surg. 2013 Jan;39(1):66-73. doi: 10.1016/j.jcrs.2012.08.058. Epub 2012 Oct 24. — View Citation

Güell JL, Verdaguer P, Elies D, Gris O, Manero F. Persistent stromal scar after PRK and CXL: different preoperative findings, similar complication. J Refract Surg. 2015 Mar;31(3):211-2. — View Citation

Koller T, Mrochen M, Seiler T. Complication and failure rates after corneal crosslinking. J Cataract Refract Surg. 2009 Aug;35(8):1358-62. doi: 10.1016/j.jcrs.2009.03.035. — View Citation

Kontadakis GA, Kankariya VP, Tsoulnaras K, Pallikaris AI, Plaka A, Kymionis GD. Long-Term Comparison of Simultaneous Topography-Guided Photorefractive Keratectomy Followed by Corneal Cross-linking versus Corneal Cross-linking Alone. Ophthalmology. 2016 May;123(5):974-83. doi: 10.1016/j.ophtha.2016.01.010. Epub 2016 Feb 17. — View Citation

Navas A, Ariza E, Haber A, Fermón S, Velázquez R, Suárez R. Bilateral keratectasia after photorefractive keratectomy. J Refract Surg. 2007 Nov;23(9):941-3. — View Citation

Raiskup F, Theuring A, Pillunat LE, Spoerl E. Corneal collagen crosslinking with riboflavin and ultraviolet-A light in progressive keratoconus: ten-year results. J Cataract Refract Surg. 2015 Jan;41(1):41-6. doi: 10.1016/j.jcrs.2014.09.033. — View Citation

Randleman JB, Woodward M, Lynn MJ, Stulting RD. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology. 2008 Jan;115(1):37-50. Epub 2007 Jul 12. — View Citation

Shaheen MS, Shalaby Bardan A, Piñero DP, Ezzeldin H, El-Kateb M, Helaly H, Khalifa MA. Wave Front-Guided Photorefractive Keratectomy Using a High-Resolution Aberrometer After Corneal Collagen Cross-Linking in Keratoconus. Cornea. 2016 Jul;35(7):946-53. doi: 10.1097/ICO.0000000000000888. — View Citation

Tomita M, Yoshida Y, Yamamoto Y, Mita M, Waring G 4th. In vivo confocal laser microscopy of morphologic changes after simultaneous LASIK and accelerated collagen crosslinking for myopia: one-year results. J Cataract Refract Surg. 2014 Jun;40(6):981-90. doi: 10.1016/j.jcrs.2013.10.044. — View Citation

* Note: There are 13 references in all — Click here to view all references

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Refractive results - spherical equivalent in diopters		30 months	Yes
Secondary	Biomicroscopy findings with the slit lamp		30 months	Yes
Secondary	Visual acuity in logMar		30 months	Yes
Secondary	Aberrometric Results in root mean square	Only coma and spherical aberration	18 months	Yes
Secondary	Topographic results in diopters	we will measure the increase in diopters with time	30 months	Yes
Secondary	Pachymetric results in micra		30 months	Yes