KeratoconusNCT04598932
Corneal Biomechanical Analysis Using Brillouin Microscopy
An observational study of Keratoconus and Keratoconus, Unstable, run by The Cleveland Clinic at 1 site in United States.
Trial summary
The objective of this study is to measure the Brillouin biomechanical properties in keratoconic corneas and characterize biomechanical alterations that occur after corneal procedures that inherently strengthen or weaken the cornea by evaluating the change in Brillouin metrics before and after treatments. Read more about this study
- Who is it for?
- Ages 18 to 60 years
- Conditions the study is for
- Keratoconus, Keratoconus, Unstable, Keratoconus, Stable
- What is being tested?
- Brillouin microscopy
- Type of treatment
- Medical device
- How many people
- 220 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jun 2021to Dec 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 to 60 years
- All sexes
- No healthy volunteers
- Adult
Study population: Group 1: Patients with normal corneas Group 2: Patients with keratoconus Group 3: Patients with normal corneas undergoing LASIK Group 4: Patients with normal corneas undergoing PRK Group 5: Patients with normal corneas undergoing SMILE Group 6: Patients with keratoconus undergoing CXL
Who may be able to join
- patients aged 18-60 with keratoconus
- patients aged 18-60 with normal corneas,
- patients aged 18-60 undergoing refractive surgery (LASIK, PRK, SMILE)
- patients aged 18-60 with keratoconus undergoing CXL
Who cannot join
- outside age range
- history of previous ocular surgeries
- unable to cooperate for the Brillouin microscopic examination
- unable to provide informed consent
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
Cleveland Clinic Cole Eye Institute
Cleveland, Ohio, 44195
About this study
The objective of this study is to measure the Brillouin biomechanical properties in keratoconic corneas and characterize biomechanical alterations that occur after corneal procedures that inherently strengthen or weaken the cornea by evaluating the change in Brillouin metrics before and after treatments.
Read the detailed description
Surgical correction of myopia and keratoconus identification/management are separate but tightly intertwined issues of major significance. For both, there is an unmet need for direct measurements to evaluate corneal stiffness (i.e. its resistance to deformation). The prevalence of myopia is expected to double, affecting more than 50% of the US population, by 2050. Laser in situ keratomileusis (LASIK) is one of the most popular and successful surgeries in the world and compares favorably to long-term contact lens wear use for myopia correction. However, only ~10% of eligible patients undergo LASIK currently; the others cite safety concerns as a major factor in their decision. The primary risk for poor refractive surgery outcomes is biomechanical failure due to unidentified (subclinical) ectasia (i.e. keratoconus). Patients presenting for LASIK evaluation with atypical, suspicious corneal curvature but with undetermined true risk represent the leading reason for surgery screening failures. This results in good candidates being denied surgery, while up to 10% of truly poor candidates are still missed using current screening algorithms.
Keratoconus is up to 10 times more prevalent than the previously reported 1/2000 figure. Corneal cross-linking (CXL) is now FDA approved in the US for keratoconus treatment and is effective at stiffening the cornea and halting ectasia progression. Early identification of keratoconus is critical, but current tests in the clinic are morphological, not biomechanical, and therefore do not allow a definitive diagnosis at the earliest stages resulting in vision loss before CXL treatment is initiated. Thus, the need for accurate identification of subclinical ectasia has never been greater.
In the past years, newly developed technology, Brillouin microscopy, has emerged as the most promising tool to address this clinical need. This study will systemically address the critical gap in current knowledge by linking Brillouin mapping of corneal biomechanical alterations to abnormal morphological behavior and testing the findings in conditions where corneal biomechanics are abruptly altered, by: 1) weakening with refractive surgery procedures, and 2) strengthening through corneal cross-linking.
It is anticipated that a clinical tool assessing the mechanical state of the cornea will improve early diagnosis and management of keratoconus as well as refractive surgery planning. Ultimately, this will lead to predictive models where Brillouin measurements could be an accurate predictor of postoperative outcomes and thus aid in developing individualized surgical parameters.
- Conditions
- Keratoconus, Keratoconus, Unstable, Keratoconus, Stable
- Being tested
- Brillouin microscopy
- Keywords
- Brillouin, Keratoconus, Keratoconus, Unstable, Corneal Cross Linking, CXL, LASIK, PRK, SMILE
- Medical subject headings
- Keratoconus
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Brillouin microscopyDevice
The Brillouin clinical instrument is comprised of three parts: a human interface, a laser-scanning confocal microscope, and an etalon-based spectrometer. The human interface is a modified ophthalmic slit-lamp instrument with chin support and headrest. The light source is a single longitudinal mode CW laser at 780 nm. A polarizing beam splitter and quarter-wave plate assembly sends the laser beam to the human interface. To focus light into the eye, a long-working distance microscope objective is used. Brillouin scattered light from the eye is collected with a single-mode optical fiber. For spectral analysis, a two-stage VIPA-etalon spectrometer configured with the cross-axis cascade principle and the spectrum is measured on a EM-CCD camera.
| Study group | Role | What they receive |
|---|---|---|
| 1: Normal Controls | Patients with normal corneas without any prior surgery to serve as the control group Receives: Device: Brillouin microscopy | |
| 2 Keratoconus | Patients with various stages of keratoconus Receives: Device: Brillouin microscopy | |
| 3: LASIK | Patients with normal corneas who are undergoing laser in situ keratomileusis (LASIK) Receives: Device: Brillouin microscopy | |
| Group 4: PRK | Patients with normal corneas who are undergoing photorefractive keratectomy (PRK) Receives: Device: Brillouin microscopy | |
| 5: SMILE | Patients with normal corneas who are undergoing small incision lenticular extraction (SMILE) Receives: Device: Brillouin microscopy | |
| 6: CXL | Patients with keratoconus who are undergoing corneal cross-linking (CXL) Receives: Device: Brillouin microscopy |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Brillouin Metrics
Brillouin metrics to be evaluated include localized Mean Brillouin modulus measure across the cornea and at each depth of the corneal stroma
Measured: Difference between baseline and 3 months after intervention
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Oct 2020
- Study start1 Jun 2021
- Primary completionJul 2027 (estimated)
- Study completionDec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for KeratoconusStudies of the same condition, open and under way.
- More trials run by The Cleveland ClinicThe 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
- Cross-sectional
- Enrolment
- 220 participants (estimated)
Sponsor and investigators
- Lead sponsor
- The Cleveland Clinic
- Sponsor type
- University, hospital or other
- Collaborators
- University of Maryland
- Responsible party
- Principal investigator, James Bradley Randleman, The Cleveland Clinic
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04598932
- Sponsor's protocol ID
- 20-355
- Status last verified
- Sep 2026
- First submitted
- 19 May 2020
- Last updated
- 1 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- No: there is no plan to share data
Publications
Zhang H, Roozbahani M, Piccinini AL, Golan O, Hafezi F, Scarcelli G, Randleman JB. Depth-Dependent Reduction of Biomechanical Efficacy of Contact Lens-Assisted Corneal Cross-linking Analyzed by Brillouin Microscopy. J Refract Surg. 2019 Nov 1;35(11):721-728. doi: 10.3928/1081597X-20191004-01.
PubMed 31710374Webb JN, Langille E, Hafezi F, Randleman JB, Scarcelli G. Biomechanical Impact of Localized Corneal Cross-linking Beyond the Irradiated Treatment Area. J Refract Surg. 2019 Apr 1;35(4):253-260. doi: 10.3928/1081597X-20190304-01.
PubMed 30984983Randleman JB, Su JP, Scarcelli G. Biomechanical Changes After LASIK Flap Creation Combined With Rapid Cross-Linking Measured With Brillouin Microscopy. J Refract Surg. 2017 Jun 1;33(6):408-414. doi: 10.3928/1081597X-20170421-01.
PubMed 28586502Scarcelli G, Pineda R, Yun SH. Brillouin optical microscopy for corneal biomechanics. Invest Ophthalmol Vis Sci. 2012 Jan 20;53(1):185-90. doi: 10.1167/iovs.11-8281.
PubMed 22159012Scarcelli G, Kling S, Quijano E, Pineda R, Marcos S, Yun SH. Brillouin microscopy of collagen crosslinking: noncontact depth-dependent analysis of corneal elastic modulus. Invest Ophthalmol Vis Sci. 2013 Feb 19;54(2):1418-25. doi: 10.1167/iovs.12-11387.
PubMed 23361513Scarcelli G, Besner S, Pineda R, Yun SH. Biomechanical characterization of keratoconus corneas ex vivo with Brillouin microscopy. Invest Ophthalmol Vis Sci. 2014 Jun 17;55(7):4490-5. doi: 10.1167/iovs.14-14450.
PubMed 24938517Scarcelli G, Besner S, Pineda R, Kalout P, Yun SH. In vivo biomechanical mapping of normal and keratoconus corneas. JAMA Ophthalmol. 2015 Apr;133(4):480-2. doi: 10.1001/jamaophthalmol.2014.5641. No abstract available.
PubMed 25611213
Study at a glance
From the registry record, last updated by the sponsor on 1 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Corneal Biomechanical Analysis Using Brillouin Microscopy
- ClinicalTrials.gov ID
- NCT04598932
- Acronym / sponsor ID
- 20-355
- Conditions
- Keratoconus, Keratoconus, Unstable, Keratoconus, Stable
- Keywords
- Brillouin, Keratoconus, Keratoconus, Unstable, Corneal Cross Linking, CXL, LASIK, PRK, SMILE
- Study type
- Observational
- Recruitment status
- Enrolling by invitation
- Enrolment
- 220 participants (estimated)
- Lead sponsor
- The Cleveland ClinicUniversity, hospital or other
- Collaborators
- University of Maryland
- Study start
- 1 Jun 2021 (actual)
- Primary completion
- Jul 2027 (estimated)
- Study completion
- Dec 2027 (estimated)
- First posted
- 22 Oct 2020 (actual)
- 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 objective of this study is to measure the Brillouin biomechanical properties in keratoconic corneas and characterize biomechanical alterations that occur after corneal procedures that inherently strengthen or weaken the cornea by evaluating the change in Brillouin metrics before and after treatments.
Detailed description
Surgical correction of myopia and keratoconus identification/management are separate but tightly intertwined issues of major significance. For both, there is an unmet need for direct measurements to evaluate corneal stiffness (i.e. its resistance to deformation). The prevalence of myopia is expected to double, affecting more than 50% of the US population, by 2050. Laser in situ keratomileusis (LASIK) is one of the most popular and successful surgeries in the world and compares favorably to long-term contact lens wear use for myopia correction. However, only ~10% of eligible patients undergo LASIK currently; the others cite safety concerns as a major factor in their decision. The primary risk for poor refractive surgery outcomes is biomechanical failure due to unidentified (subclinical) ectasia (i.e. keratoconus). Patients presenting for LASIK evaluation with atypical, suspicious corneal curvature but with undetermined true risk represent the leading reason for surgery screening failures. This results in good candidates being denied surgery, while up to 10% of truly poor candidates are still missed using current screening algorithms.
Keratoconus is up to 10 times more prevalent than the previously reported 1/2000 figure. Corneal cross-linking (CXL) is now FDA approved in the US for keratoconus treatment and is effective at stiffening the cornea and halting ectasia progression. Early identification of keratoconus is critical, but current tests in the clinic are morphological, not biomechanical, and therefore do not allow a definitive diagnosis at the earliest stages resulting in vision loss before CXL treatment is initiated. Thus, the need for accurate identification of subclinical ectasia has never been greater.
In the past years, newly developed technology, Brillouin microscopy, has emerged as the most promising tool to address this clinical need. This study will systemically address the critical gap in current knowledge by linking Brillouin mapping of corneal biomechanical alterations to abnormal morphological behavior and testing the findings in conditions where corneal biomechanics are abruptly altered, by: 1) weakening with refractive surgery procedures, and 2) strengthening through corneal cross-linking.
It is anticipated that a clinical tool assessing the mechanical state of the cornea will improve early diagnosis and management of keratoconus as well as refractive surgery planning. Ultimately, this will lead to predictive models where Brillouin measurements could be an accurate predictor of postoperative outcomes and thus aid in developing individualized surgical parameters.
Study design
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Number of arms
- 6
| Arm | Type | Receives |
|---|---|---|
| 1: Normal Controls | – | Device: Brillouin microscopyPatients with normal corneas without any prior surgery to serve as the control group |
| 2 Keratoconus | – | Device: Brillouin microscopyPatients with various stages of keratoconus |
| 3: LASIK | – | Device: Brillouin microscopyPatients with normal corneas who are undergoing laser in situ keratomileusis (LASIK) |
| Group 4: PRK | – | Device: Brillouin microscopyPatients with normal corneas who are undergoing photorefractive keratectomy (PRK) |
| 5: SMILE | – | Device: Brillouin microscopyPatients with normal corneas who are undergoing small incision lenticular extraction (SMILE) |
| 6: CXL | – | Device: Brillouin microscopyPatients with keratoconus who are undergoing corneal cross-linking (CXL) |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
- Study population
- Group 1: Patients with normal corneas Group 2: Patients with keratoconus Group 3: Patients with normal corneas undergoing LASIK Group 4: Patients with normal corneas undergoing PRK Group 5: Patients with normal corneas undergoing SMILE Group 6: Patients with keratoconus undergoing CXL
Key inclusion criteria (4 listed)
- patients aged 18-60 with keratoconus
- patients aged 18-60 with normal corneas,
- patients aged 18-60 undergoing refractive surgery (LASIK, PRK, SMILE)
- patients aged 18-60 with keratoconus undergoing CXL
Key exclusion criteria (4 listed)
- outside age range
- history of previous ocular surgeries
- unable to cooperate for the Brillouin microscopic examination
- unable to provide informed consent
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 |
|---|---|---|
| Brillouin microscopyThe Brillouin clinical instrument is comprised of three parts: a human interface, a laser-scanning confocal microscope, and an etalon-based spectrometer. The human interface is a modified ophthalmic slit-lamp instrument with chin support and headrest. The light source is a single longitudinal mode CW laser at 780 nm. A polarizing beam splitter and quarter-wave plate assembly sends the laser beam to the human interface. To focus light into the eye, a long-working distance microscope objective is used. Brillouin scattered light from the eye is collected with a single-mode optical fiber. For spectral analysis, a two-stage VIPA-etalon spectrometer configured with the cross-axis cascade principle and the spectrum is measured on a EM-CCD camera. | Device | 1: Normal Controls, 2 Keratoconus, 3: LASIK, 5: SMILE, 6: CXL, Group 4: PRK |
Primary outcome
Change in Brillouin Metrics
Time frame: Difference between baseline and 3 months after intervention
Brillouin metrics to be evaluated include localized Mean Brillouin modulus measure across the cornea and at each depth of the corneal stroma
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Oct 2026.
- Background: PubMed 31710374Zhang H, Roozbahani M, Piccinini AL, Golan O, Hafezi F, Scarcelli G, Randleman JB. Depth-Dependent Reduction of Biomechanical Efficacy of Contact Lens-Assisted Corneal Cross-linking Analyzed by Brillouin Microscopy. J Refract Surg. 2019 Nov 1;35(11):721-728. doi: 10.3928/1081597X-20191004-01.
- Background: PubMed 30984983Webb JN, Langille E, Hafezi F, Randleman JB, Scarcelli G. Biomechanical Impact of Localized Corneal Cross-linking Beyond the Irradiated Treatment Area. J Refract Surg. 2019 Apr 1;35(4):253-260. doi: 10.3928/1081597X-20190304-01.
- Background: PubMed 28586502Randleman JB, Su JP, Scarcelli G. Biomechanical Changes After LASIK Flap Creation Combined With Rapid Cross-Linking Measured With Brillouin Microscopy. J Refract Surg. 2017 Jun 1;33(6):408-414. doi: 10.3928/1081597X-20170421-01.
- Results publication: PubMed 22159012Scarcelli G, Pineda R, Yun SH. Brillouin optical microscopy for corneal biomechanics. Invest Ophthalmol Vis Sci. 2012 Jan 20;53(1):185-90. doi: 10.1167/iovs.11-8281.
- Results publication: PubMed 23361513Scarcelli G, Kling S, Quijano E, Pineda R, Marcos S, Yun SH. Brillouin microscopy of collagen crosslinking: noncontact depth-dependent analysis of corneal elastic modulus. Invest Ophthalmol Vis Sci. 2013 Feb 19;54(2):1418-25. doi: 10.1167/iovs.12-11387.
- Results publication: PubMed 24938517Scarcelli G, Besner S, Pineda R, Yun SH. Biomechanical characterization of keratoconus corneas ex vivo with Brillouin microscopy. Invest Ophthalmol Vis Sci. 2014 Jun 17;55(7):4490-5. doi: 10.1167/iovs.14-14450.
- Results publication: PubMed 25611213Scarcelli G, Besner S, Pineda R, Kalout P, Yun SH. In vivo biomechanical mapping of normal and keratoconus corneas. JAMA Ophthalmol. 2015 Apr;133(4):480-2. doi: 10.1001/jamaophthalmol.2014.5641. No abstract available.
- Individual participant dataSharing planned: No. there is no plan to share data
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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.
The record lists no contact. Use the official record to reach the sponsor.
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 and Keratoconus, Unstable, run by The Cleveland Clinic 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 4 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: enrolling by invitation, as of the sponsor's last update on 1 Oct 2026. 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?
This study is still under way. Results are not available in the source record yet.
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?
Change in Brillouin Metrics (time frame: Difference between baseline and 3 months after intervention). 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 NCT04598932, which also lists 7 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 1 Oct 2026.