Clinical trial NCT02943967: Corneal Cross-linking and Refractive Surface Ablation in Patients With Asymmetric Corneas
Official title: Two Years Follow up of Corneal Cor Cross-linking and Refractive Surface Ablation in Patients With Asymmetric Corneal Topography
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Surgical Procedure, Unspecified
Keywords: Refractive Surgical Procedures
Photorefractive Keratectomy
Aberrometry
Lead sponsor: Federal University of São Paulo
Sponsor class: OTHER
First posted: 2016-10-25
Enrollment: 44
Sex: ALL
Minimum age (years): 23
Maximum age (years): 51
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief 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.

Detailed 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.

Eligibility criteria: 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

Primary outcomes:
measure: Refractive results - spherical equivalent in diopters
timeFrame: 30 months
Secondary outcomes:
measure: Biomicroscopy findings with the slit lamp
timeFrame: 30 months
measure: Visual acuity in logMar
timeFrame: 30 months
measure: Aberrometric Results in root mean square
timeFrame: 18 months
measure: Topographic results in diopters
timeFrame: 30 months
measure: Pachymetric results in micra
timeFrame: 30 months
Other outcomes:
Locations:
city: Sao Paulo
country: Brazil
facility: Federal University of São Paulo
Study officials:
affiliation: Federal University of São Paulo
name: Mauro Campos, MD
role: PRINCIPAL_INVESTIGATOR
References:
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.
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.
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. doi: 10.1016/s0886-3350(02)01701-7.
citation: Randleman JB, Woodward M, Lynn MJ, Stulting RD. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology. 2008 Jan;115(1):37-50. doi: 10.1016/j.ophtha.2007.03.073. Epub 2007 Jul 12.
citation: Navas A, Ariza E, Haber A, Fermon S, Velazquez R, Suarez R. Bilateral keratectasia after photorefractive keratectomy. J Refract Surg. 2007 Nov;23(9):941-3. doi: 10.3928/1081-597X-20071101-14.
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.
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.
citation: 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.
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.
citation: Camellin M, Guidotti JM, Arba Mosquera S. Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus. J Optom. 2017 Jan-Mar;10(1):52-62. doi: 10.1016/j.optom.2016.02.001. Epub 2016 Mar 21.
citation: Shaheen MS, Shalaby Bardan A, Pinero 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.
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.
citation: Guell 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. No abstract available.