Measurements of Patients Using OCT Before and After LASIKNCT01893671
Corneal Power, Astigmatism, and Aberration Changes After LASIK
An observational study of Measurements of Patients Using OCT Before and After LASIK, run by Oregon Health and Science University at 1 site in United States.
Trial summary
The primary goal of the study is to determine if Optical Coherence Tomography (OCT) measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography. A second goal is to evaluate OCT-based epithelial thickness mapping. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Measurements of Patients Using OCT Before and After LASIK
- How many people
- 22 participants
- Where
- 1 siteUnited States
- Study dates
- Jan 2011to 31 Aug 2017
- 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 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Subjects undergoing routine LASIK for the correction of myopia or hyperopia with or without astigmatism
Who may be able to join
- 1. Patients who qualify for primary LASIK for either myopia or hyperopia, with or without astigmatism.
Who cannot join
- Inability to give informed consent.
- Inability to maintain stable fixation for OCT imaging.
- Inability to commit to required visits to complete the study.
- Eyes with concurrent cataract, retinal diseases, glaucoma, or other eye conditions that may limit the visual outcome after surgery
Trial locations and contacts
1 site in 1 country.
United States1 site
Oregon Health & Science University
Portland, Oregon, 97239
About this study
Official title: Observational Study of Corneal Power, Astigmatism, and Aberration Changes After LASIK
The primary goal of the study is to determine if Optical Coherence Tomography (OCT) measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography. A second goal is to evaluate OCT-based epithelial thickness mapping. The postoperative epithelial thickness variation will be used to calculate refractive effects and calibrate the smoothing parameter in the mathematical model relating corneal mean curvature and epithelial thickness. A third goal is to assess the repeatability of OCT measurements. A fourth goal is to develop a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens based on measurements of the lens' anterior and posterior capsular topographies and positions with the ultrahigh-speed MIT OCT prototype.
Read the detailed description
A prospective observational study on refraction and HOA changes after LASIK will be conducted at OHSU and Baylor. We will enroll 50 subjects undergoing routine LASIK for the correction of myopia or hyperopia. The Optovue anterior segment OCT prototype will be used to measure corneal power, astigmatism, HOA, and epithelial thickness map. The ultrahigh-speed MIT OCT prototypes will also be used when they become available. A comprehensive eye examination will be performed preoperatively. OCT scan, manifest refraction, visual acuity, Placido-ring corneal topography, slit scanning/Scheimpflug camera, and wavefront measurements will be acquired preoperatively and 3-6 months after the surgery. The LASIK-induced refraction and wavefront HOA changes will be used as the reference standard to evaluate the accuracy of OCT-measured corneal power, astigmatism, and HOA changes. The primary goal of the study is to determine if OCT measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography. A second goal is to evaluate OCT-based epithelial thickness mapping. The postoperative epithelial thickness variation will be used to calculate refractive effects and calibrate the smoothing parameter in the mathematical model relating corneal mean curvature and epithelial thickness. A third goal is to assess the repeatability of OCT measurements. A fourth goal is to develop a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens based on measurements of the lens' anterior and posterior capsular topographies and positions with the ultrahigh-speed MIT OCT prototype. The reference standard for lens focusing power and astigmatism will be based on a Gaussian optics model that takes as inputs manifest refraction, crystalline lens position, axial eye length, and OCT corneal power and astigmatism measurements. The reference standard for lens HOA will be the difference between wavefront HOA and corneal HOA. For each eye, the best-fit effective index of the lens will be found so that OCT measurements will match the reference data. Although the lens index is likely to be higher centrally than peripherally, this secondary perturbation will be accounted for by a posterior shift of the posterior lens capsule in OCT images, due to the fact that apparent distances in OCT images is a product of physical distance and optical group index. Thus HOA due to index variation in the lens would translate to unevenness in the posterior capsule surface that could be measured with OCT.
- Keywords
- LASIK, corneal power, astigmatism, HOA, Optical Coherence Tomography
- Medical subject headings
- Astigmatism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| LASIK | Subjects undergoing routine LASIK for the correction of myopia or hyperopia. |
What is being measured
The primary outcome is the main question the study is designed to answer.
OCT measurement of corneal power and astigmatism vs Placido-ring
primary goal of the study is to determine if OCT measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography
Measured: 5 year
Secondary outcomes (3)
An evaluation of OCT-based epithelial thickness mapping
The postoperative epithelial thickness variation will be used to calculate refractive effects and calibrate the smoothing parameter in the mathematical model relating corneal mean curvature and epithelial thickness.
Measured: 5 year
OCT measurements repeatability
An assessment of the repeatability of OCT measurements
Measured: 5 year
The Development of a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens
The Development of a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens based on measurements of the lens' anterior and posterior capsular topographies and positions with the ultrahigh-speed MIT OCT prototype.
Measured: 5 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Jul 2013 (estimated)
- Study startJan 2011
- Primary completion31 Aug 2017
- Study completion31 Aug 2017
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Measurements of Patients Using OCT Before and After LASIKStudies of the same condition, open and under way.
- More trials run by Oregon Health and Science UniversityThe 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 only
- Time perspective
- Prospective
- Enrolment
- 22 participants (actual)
Sponsor and investigators
- Lead sponsor
- Oregon Health and Science University
- Sponsor type
- University, hospital or other
- Collaborators
- National Eye Institute (NEI)
- Responsible party
- Principal investigator, David Huang, Oregon Health and Science University
- Investigators
- David Huang, MD, PhD, Principal investigator, Oregon Health & Science Universtiy
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01893671
- Sponsor's protocol ID
- OHSU IRB#6612
- Other IDs
- R01EY018184
- Status last verified
- Apr 2018
- First submitted
- 2 Jul 2013
- Last updated
- 5 Apr 2018
- Results posted
- No
Study at a glance
From the registry record, last updated by the sponsor on 5 Apr 2018. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Observational Study of Corneal Power, Astigmatism, and Aberration Changes After LASIK
- ClinicalTrials.gov ID
- NCT01893671
- Acronym / sponsor ID
- OHSU IRB#6612
- Keywords
- LASIK, corneal power, astigmatism, HOA, Optical Coherence Tomography
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 22 participants (actual)
- Lead sponsor
- Oregon Health and Science UniversityUniversity, hospital or other
- Collaborators
- National Eye Institute (NEI)
- Study start
- Jan 2011
- Primary completion
- 31 Aug 2017 (actual)
- Study completion
- 31 Aug 2017 (actual)
- First posted
- 9 Jul 2013 (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 primary goal of the study is to determine if Optical Coherence Tomography (OCT) measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography. A second goal is to evaluate OCT-based epithelial thickness mapping. The postoperative epithelial thickness variation will be used to calculate refractive effects and calibrate the smoothing parameter in the mathematical model relating corneal mean curvature and epithelial thickness. A third goal is to assess the repeatability of OCT measurements. A fourth goal is to develop a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens based on measurements of the lens' anterior and posterior capsular topographies and positions with the ultrahigh-speed MIT OCT prototype.
Detailed description
A prospective observational study on refraction and HOA changes after LASIK will be conducted at OHSU and Baylor. We will enroll 50 subjects undergoing routine LASIK for the correction of myopia or hyperopia. The Optovue anterior segment OCT prototype will be used to measure corneal power, astigmatism, HOA, and epithelial thickness map. The ultrahigh-speed MIT OCT prototypes will also be used when they become available. A comprehensive eye examination will be performed preoperatively. OCT scan, manifest refraction, visual acuity, Placido-ring corneal topography, slit scanning/Scheimpflug camera, and wavefront measurements will be acquired preoperatively and 3-6 months after the surgery. The LASIK-induced refraction and wavefront HOA changes will be used as the reference standard to evaluate the accuracy of OCT-measured corneal power, astigmatism, and HOA changes. The primary goal of the study is to determine if OCT measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography. A second goal is to evaluate OCT-based epithelial thickness mapping. The postoperative epithelial thickness variation will be used to calculate refractive effects and calibrate the smoothing parameter in the mathematical model relating corneal mean curvature and epithelial thickness. A third goal is to assess the repeatability of OCT measurements. A fourth goal is to develop a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens based on measurements of the lens' anterior and posterior capsular topographies and positions with the ultrahigh-speed MIT OCT prototype. The reference standard for lens focusing power and astigmatism will be based on a Gaussian optics model that takes as inputs manifest refraction, crystalline lens position, axial eye length, and OCT corneal power and astigmatism measurements. The reference standard for lens HOA will be the difference between wavefront HOA and corneal HOA. For each eye, the best-fit effective index of the lens will be found so that OCT measurements will match the reference data. Although the lens index is likely to be higher centrally than peripherally, this secondary perturbation will be accounted for by a posterior shift of the posterior lens capsule in OCT images, due to the fact that apparent distances in OCT images is a product of physical distance and optical group index. Thus HOA due to index variation in the lens would translate to unevenness in the posterior capsule surface that could be measured with OCT.
Study design
- Observational model
- Case only
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| LASIK | – | –Subjects undergoing routine LASIK for the correction of myopia or hyperopia. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Subjects undergoing routine LASIK for the correction of myopia or hyperopia with or without astigmatism
Key inclusion criteria (1 listed)
- 1. Patients who qualify for primary LASIK for either myopia or hyperopia, with or without astigmatism.
Key exclusion criteria (4 listed)
- Inability to give informed consent.
- Inability to maintain stable fixation for OCT imaging.
- Inability to commit to required visits to complete the study.
- Eyes with concurrent cataract, retinal diseases, glaucoma, or other eye conditions that may limit the visual outcome after surgery
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
OCT measurement of corneal power and astigmatism vs Placido-ring
Time frame: 5 year
primary goal of the study is to determine if OCT measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography
3 secondary outcomes
An evaluation of OCT-based epithelial thickness mapping
Time frame: 5 year
OCT measurements repeatability
Time frame: 5 year
The Development of a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens
Time frame: 5 year
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 5 Apr 2018.
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.
David Huang, MD, PhD principal investigator
Oregon Health & Science Universtiy
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 Measurements of Patients Using OCT Before and After LASIK, run by Oregon Health and Science University at 1 site in United States.
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 4 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 5 Apr 2018. 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 United States. 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?
OCT measurement of corneal power and astigmatism vs Placido-ring (time frame: 5 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 5 Apr 2018.