KeratoconusNCT02698709
Astigmatic Vector Analysis of Posterior Cornea - a Comparison Among Healthy, Forme Fruste and Overt Keratoconus Corneas
An observational study of Keratoconus, run by University of Sao Paulo at 1 site in Brazil.
Trial summary
The main purpose of this study is to determine new diagnostic criteria for an eye disease called keratoconus. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Keratoconus
- What is being tested?
- Analysis of anterior and posterior corneal surfaces
- How many people
- 698 participants
- Where
- 1 siteBrazil
- Study dates
- May 2015to Sep 2015
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: Two databases of patients were examined at the Instituto de Olhos Renato Ambrósio (Rio de Janeiro, Brazil), between July 2004 and October 2013. One of the databases contained information of normal candidates to refractive surgery who did not develop any sign of corneal ectasia after laser in situ keratomileusis during a two year follow-up period (C). The second database included information concerning corneas with keratoconus (Kc), categorized as overt Kc, if both eyes manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers; or forme fruste (FFKc), if only one eye exhibited such features.
Who may be able to join
- Good-quality Scheimpflug scans (approved by the device in the ''Examination Quality Specification'').
Who cannot join
- Previous eye surgery or trauma, and any sort of corneal scarring that might interfere with keratometric data acquisition.
Trial locations and contacts
1 site in 1 country.
Brazil1 site
Clínica Oftalmológica do Hospital de Clínicas - FMUSP
São Paulo, São Paulo, 05.403-001
About this study
Official title: Astigmatic Vector Analysis of Posterior Corneal Surface - a Comparison Among Healthy, Forme Fruste and Overt Keratoconus Corneas
The main purpose of this study is to determine new diagnostic criteria for an eye disease called keratoconus.
Read the detailed description
Eyes of patients who distinctly present signs of keratoconus, for both eyes, at corneal tomography (an exam commonly used in such cases), and those who present such signs in only one eye were compared to eyes of unaffected patients. Several characteristics of anterior and posterior corneal astigmatism (special emphasis was given to the latter) were collectively assessed among all patients by a method referred to as vectorial analysis. Statistical tests were then performed, in an attempt to highlight differences among those three groups of patients and, eventually, define new diagnostic criteria.
- Conditions
- Keratoconus
- Being tested
- Analysis of anterior and posterior corneal surfaces
- Keywords
- Keratoconus, Corneal Topography, Diagnosis, Keratomileusis, Laser In Situ
- Medical subject headings
- Keratoconus, Disease
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Analysis of anterior and posterior corneal surfacesOther
Also called Thibos' vectorial astigmatism analysis
Corneal data obtained from a Scheimpflug-based topographer were converted to astigmatic vectors in accordance to the method proposed by Thibos
| Study group | Role | What they receive |
|---|---|---|
| Healthy corneas (C) | Corneas of normal candidates to refractive surgery who did not develop any sign of corneal ectasia after laser in situ keratomileusis during a two year follow-up period were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos. Receives: Other: Analysis of anterior and posterior corneal surfaces | |
| Overt keratoconus (Kc) | Whether both eyes manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers. Such eyes were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos. Receives: Other: Analysis of anterior and posterior corneal surfaces | |
| Forme fruste keratoconus (FFKc) | Whether only one eye manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers, and the fellow eye seemed unaffected. Such unaffected eyes were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos. Receives: Other: Analysis of anterior and posterior corneal surfaces |
What is being measured
The primary outcome is the main question the study is designed to answer.
Astigmatism corneal vectors (based on keratometric readings at the three millimeter optical zones for both corneal surfaces).
Corneal tomography at an Scheimpflug-based tomographer
Measured: Through study completion, an average of 6 months.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Mar 2016 (estimated)
- Study startMay 2015
- Primary completionAug 2015
- Study completionSep 2015
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (30)Papers the sponsor has linked to this study.
- Other trials for KeratoconusStudies of the same condition, open and under way.
- More trials run by University of Sao PauloThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Retrospective
- Enrolment
- 698 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Sao Paulo
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Giuliano de Oliveira Freitas, MD., University of Sao Paulo
- Investigators
- Milton R Alves, MD, PhD, Study director, Clínica Oftalmológica HCFM/USP
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT02698709
- Sponsor's protocol ID
- Clínica Oftalmológica HCFM/USP
- Status last verified
- Feb 2016
- First submitted
- 24 Feb 2016
- Last updated
- 4 Mar 2016
- Results posted
- No
- Data monitoring committee
- Yes
- Individual data sharing
- No
Publications
Li X, Yang H, Rabinowitz YS. Keratoconus: classification scheme based on videokeratography and clinical signs. J Cataract Refract Surg. 2009 Sep;35(9):1597-603. doi: 10.1016/j.jcrs.2009.03.050.
PubMed 19683159Goebels S, Eppig T, Wagenpfeil S, Cayless A, Seitz B, Langenbucher A. Staging of keratoconus indices regarding tomography, topography, and biomechanical measurements. Am J Ophthalmol. 2015 Apr;159(4):733-8. doi: 10.1016/j.ajo.2015.01.014. Epub 2015 Jan 26.
PubMed 25634534Moreira LB, Bardal RA, Crisigiovanni LR. Contact lenses fitting after intracorneal ring segments implantation in keratoconus. Arq Bras Oftalmol. 2013 Jul-Aug;76(4):215-7. doi: 10.1590/s0004-27492013000400004.
PubMed 24061830Raiskup 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.
PubMed 25532633Gomes JA, Tan D, Rapuano CJ, Belin MW, Ambrosio R Jr, Guell JL, Malecaze F, Nishida K, Sangwan VS; Group of Panelists for the Global Delphi Panel of Keratoconus and Ectatic Diseases. Global consensus on keratoconus and ectatic diseases. Cornea. 2015 Apr;34(4):359-69. doi: 10.1097/ICO.0000000000000408.
PubMed 25738235Muftuoglu O, Ayar O, Ozulken K, Ozyol E, Akinci A. Posterior corneal elevation and back difference corneal elevation in diagnosing forme fruste keratoconus in the fellow eyes of unilateral keratoconus patients. J Cataract Refract Surg. 2013 Sep;39(9):1348-57. doi: 10.1016/j.jcrs.2013.03.023. Epub 2013 Jun 29.
PubMed 23820305Smadja D, Santhiago MR, Mello GR, Krueger RR, Colin J, Touboul D. Influence of the reference surface shape for discriminating between normal corneas, subclinical keratoconus, and keratoconus. J Refract Surg. 2013 Apr;29(4):274-81. doi: 10.3928/1081597X-20130318-07.
PubMed 23557226Torricelli AA, Bechara SJ, Wilson SE. Screening of refractive surgery candidates for LASIK and PRK. Cornea. 2014 Oct;33(10):1051-5. doi: 10.1097/ICO.0000000000000171.
PubMed 25014146Randleman JB, Akhtar J, Lynn MJ, Ambrosio R Jr, Dupps WJ Jr, Krueger RR, Klyce SD. Comparison of objective and subjective refractive surgery screening parameters between regular and high-resolution Scheimpflug imaging devices. J Cataract Refract Surg. 2015 Feb;41(2):286-94. doi: 10.1016/j.jcrs.2014.06.026. Epub 2014 Dec 20.
PubMed 25537685Ramos IC, Correa R, Guerra FP, Trattler W, Belin MW, Klyce SD, Fontes BM, Schor P, Smolek MK, Dawson DG, Chalita MR, Cazal JO, Ruiz M, Randleman JB, Ambrosio R Jr. Variability of subjective classifications of corneal topography maps from LASIK candidates. J Refract Surg. 2013 Nov;29(11):770-5. doi: 10.3928/1081597X-20130823-01. Epub 2013 Aug 30.
PubMed 23980708Qin B, Chen S, Brass R, Li Y, Tang M, Zhang X, Wang X, Wang Q, Huang D. Keratoconus diagnosis with optical coherence tomography-based pachymetric scoring system. J Cataract Refract Surg. 2013 Dec;39(12):1864-71. doi: 10.1016/j.jcrs.2013.05.048.
PubMed 24427794Ruisenor Vazquez PR, Galletti JD, Minguez N, Delrivo M, Fuentes Bonthoux F, Pfortner T, Galletti JG. Pentacam Scheimpflug tomography findings in topographically normal patients and subclinical keratoconus cases. Am J Ophthalmol. 2014 Jul;158(1):32-40.e2. doi: 10.1016/j.ajo.2014.03.018. Epub 2014 Apr 5.
PubMed 24709808Buhren J, Schaffeler T, Kohnen T. Validation of metrics for the detection of subclinical keratoconus in a new patient collective. J Cataract Refract Surg. 2014 Feb;40(2):259-68. doi: 10.1016/j.jcrs.2013.07.044. Epub 2013 Dec 18.
PubMed 24360499Galletti JD, Ruisenor Vazquez PR, Minguez N, Delrivo M, Bonthoux FF, Pfortner T, Galletti JG. Corneal asymmetry analysis by pentacam scheimpflug tomography for keratoconus diagnosis. J Refract Surg. 2015 Feb;31(2):116-23. doi: 10.3928/1081597X-20150122-07.
PubMed 25735045Ambrosio R Jr, Valbon BF, Faria-Correia F, Ramos I, Luz A. Scheimpflug imaging for laser refractive surgery. Curr Opin Ophthalmol. 2013 Jul;24(4):310-20. doi: 10.1097/ICU.0b013e3283622a94.
PubMed 23680761
Study at a glance
From the registry record, last updated by the sponsor on 4 Mar 2016. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Astigmatic Vector Analysis of Posterior Corneal Surface - a Comparison Among Healthy, Forme Fruste and Overt Keratoconus Corneas
- ClinicalTrials.gov ID
- NCT02698709
- Acronym / sponsor ID
- Clínica Oftalmológica HCFM/USP
- Conditions
- Keratoconus
- Keywords
- Keratoconus, Corneal Topography, Diagnosis, Keratomileusis, Laser In Situ
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 698 participants (actual)
- Lead sponsor
- University of Sao PauloUniversity, hospital or other
- Study start
- May 2015
- Primary completion
- Aug 2015 (actual)
- Study completion
- Sep 2015 (actual)
- First posted
- 4 Mar 2016 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The main purpose of this study is to determine new diagnostic criteria for an eye disease called keratoconus.
Detailed description
Eyes of patients who distinctly present signs of keratoconus, for both eyes, at corneal tomography (an exam commonly used in such cases), and those who present such signs in only one eye were compared to eyes of unaffected patients. Several characteristics of anterior and posterior corneal astigmatism (special emphasis was given to the latter) were collectively assessed among all patients by a method referred to as vectorial analysis. Statistical tests were then performed, in an attempt to highlight differences among those three groups of patients and, eventually, define new diagnostic criteria.
Study design
- Observational model
- Case-control
- Time perspective
- Retrospective
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Healthy corneas (C) | – | Other: Analysis of anterior and posterior corneal surfacesCorneas of normal candidates to refractive surgery who did not develop any sign of corneal ectasia after laser in situ keratomileusis during a two year follow-up period were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos. |
| Overt keratoconus (Kc) | – | Other: Analysis of anterior and posterior corneal surfacesWhether both eyes manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers. Such eyes were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos. |
| Forme fruste keratoconus (FFKc) | – | Other: Analysis of anterior and posterior corneal surfacesWhether only one eye manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers, and the fellow eye seemed unaffected. Such unaffected eyes were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Two databases of patients were examined at the Instituto de Olhos Renato Ambrósio (Rio de Janeiro, Brazil), between July 2004 and October 2013. One of the databases contained information of normal candidates to refractive surgery who did not develop any sign of corneal ectasia after laser in situ keratomileusis during a two year follow-up period (C). The second database included information concerning corneas with keratoconus (Kc), categorized as overt Kc, if both eyes manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers; or forme fruste (FFKc), if only one eye exhibited such features.
Key inclusion criteria (1 listed)
- Good-quality Scheimpflug scans (approved by the device in the ''Examination Quality Specification'').
Key exclusion criteria (1 listed)
- Previous eye surgery or trauma, and any sort of corneal scarring that might interfere with keratometric data acquisition.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Analysis of anterior and posterior corneal surfacesAlso: Thibos' vectorial astigmatism analysisCorneal data obtained from a Scheimpflug-based topographer were converted to astigmatic vectors in accordance to the method proposed by Thibos | Other | Forme fruste keratoconus (FFKc), Healthy corneas (C), Overt keratoconus (Kc) |
Primary outcome
Astigmatism corneal vectors (based on keratometric readings at the three millimeter optical zones for both corneal surfaces).
Time frame: Through study completion, an average of 6 months.
Corneal tomography at an Scheimpflug-based tomographer
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 4 Mar 2016.
- Results publication: PubMed 19683159Li X, Yang H, Rabinowitz YS. Keratoconus: classification scheme based on videokeratography and clinical signs. J Cataract Refract Surg. 2009 Sep;35(9):1597-603. doi: 10.1016/j.jcrs.2009.03.050.
- Results publication: PubMed 25634534Goebels S, Eppig T, Wagenpfeil S, Cayless A, Seitz B, Langenbucher A. Staging of keratoconus indices regarding tomography, topography, and biomechanical measurements. Am J Ophthalmol. 2015 Apr;159(4):733-8. doi: 10.1016/j.ajo.2015.01.014. Epub 2015 Jan 26.
- Results publication: PubMed 24061830Moreira LB, Bardal RA, Crisigiovanni LR. Contact lenses fitting after intracorneal ring segments implantation in keratoconus. Arq Bras Oftalmol. 2013 Jul-Aug;76(4):215-7. doi: 10.1590/s0004-27492013000400004.
- Results publication: PubMed 25532633Raiskup 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.
- Results publication: PubMed 25738235Gomes JA, Tan D, Rapuano CJ, Belin MW, Ambrosio R Jr, Guell JL, Malecaze F, Nishida K, Sangwan VS; Group of Panelists for the Global Delphi Panel of Keratoconus and Ectatic Diseases. Global consensus on keratoconus and ectatic diseases. Cornea. 2015 Apr;34(4):359-69. doi: 10.1097/ICO.0000000000000408.
- Results publication: PubMed 23820305Muftuoglu O, Ayar O, Ozulken K, Ozyol E, Akinci A. Posterior corneal elevation and back difference corneal elevation in diagnosing forme fruste keratoconus in the fellow eyes of unilateral keratoconus patients. J Cataract Refract Surg. 2013 Sep;39(9):1348-57. doi: 10.1016/j.jcrs.2013.03.023. Epub 2013 Jun 29.
- Results publication: PubMed 23557226Smadja D, Santhiago MR, Mello GR, Krueger RR, Colin J, Touboul D. Influence of the reference surface shape for discriminating between normal corneas, subclinical keratoconus, and keratoconus. J Refract Surg. 2013 Apr;29(4):274-81. doi: 10.3928/1081597X-20130318-07.
- Results publication: PubMed 25014146Torricelli AA, Bechara SJ, Wilson SE. Screening of refractive surgery candidates for LASIK and PRK. Cornea. 2014 Oct;33(10):1051-5. doi: 10.1097/ICO.0000000000000171.
- Results publication: PubMed 25537685Randleman JB, Akhtar J, Lynn MJ, Ambrosio R Jr, Dupps WJ Jr, Krueger RR, Klyce SD. Comparison of objective and subjective refractive surgery screening parameters between regular and high-resolution Scheimpflug imaging devices. J Cataract Refract Surg. 2015 Feb;41(2):286-94. doi: 10.1016/j.jcrs.2014.06.026. Epub 2014 Dec 20.
- Results publication: PubMed 23980708Ramos IC, Correa R, Guerra FP, Trattler W, Belin MW, Klyce SD, Fontes BM, Schor P, Smolek MK, Dawson DG, Chalita MR, Cazal JO, Ruiz M, Randleman JB, Ambrosio R Jr. Variability of subjective classifications of corneal topography maps from LASIK candidates. J Refract Surg. 2013 Nov;29(11):770-5. doi: 10.3928/1081597X-20130823-01. Epub 2013 Aug 30.
- Results publication: PubMed 24427794Qin B, Chen S, Brass R, Li Y, Tang M, Zhang X, Wang X, Wang Q, Huang D. Keratoconus diagnosis with optical coherence tomography-based pachymetric scoring system. J Cataract Refract Surg. 2013 Dec;39(12):1864-71. doi: 10.1016/j.jcrs.2013.05.048.
- Results publication: PubMed 24709808Ruisenor Vazquez PR, Galletti JD, Minguez N, Delrivo M, Fuentes Bonthoux F, Pfortner T, Galletti JG. Pentacam Scheimpflug tomography findings in topographically normal patients and subclinical keratoconus cases. Am J Ophthalmol. 2014 Jul;158(1):32-40.e2. doi: 10.1016/j.ajo.2014.03.018. Epub 2014 Apr 5.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Milton R Alves, MD, PhD study director
Clínica Oftalmológica HCFM/USP
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Keratoconus, run by University of Sao Paulo at 1 site in Brazil.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 4 Mar 2016. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Brazil. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Astigmatism corneal vectors (based on keratometric readings at the three millimeter optical zones for both corneal surfaces). (time frame: Through study completion, an average of 6 months.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT02698709, which also lists 30 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 4 Mar 2016.