MyopiaNCT06818461
Assessment of Corneal Biomechanical Properties Using Corvis ST and ECD Following LASIK, PRK, CXL, Veriflex IOL and Implantable Collamer Lens
An observational study of Myopia and Keratoconus, run by Beni-Suef University at 1 site in Egypt.
Trial summary
To evaluate corneal biomechanical changes using the Corvis ST and ECD in patients who have under-gone LASIK, PRK, corneal cross-linking (CXL), Veriflex IOL and ICL. Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Myopia, Keratoconus, Refractive Surgery
- What is being tested?
- Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICL
- How many people
- 150 participants
- Where
- 1 siteEgypt
- Study dates
- 1 Jan 2025to 31 Oct 2025
- 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 to 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: patients coming for refractive surgery
Who may be able to join
- 1. Adults aged 18-60 years. 2. Patients who have undergone LASIK, PRK, or CXL at least 1 month prior to measure-ment.
- 3. Stable refraction for at least 3 months post-procedure. 4. No evidence of active ocular disease or infection.
Who cannot join
- 1. History of other ocular surgeries (excluding LASIK, PRK, or CXL). 2. Presence of keratoconus or other corneal ectatic disorders not treated with CXL.
- 3. Systemic or ocular conditions affecting corneal biomechanical properties (e.g., dia-betes, connective tissue disorders).
- 4. Current or recent use of medications influencing corneal biomechanics.
Trial locations and contacts
1 site in 1 country.
About this study
To evaluate corneal biomechanical changes using the Corvis ST and ECD in patients who have under-gone LASIK, PRK, corneal cross-linking (CXL), Veriflex IOL and ICL.
Read the detailed description
This observational study aims to evaluate corneal biomechanical changes and ECD in patients who have undergone LASIK, PRK, corneal cross-linking (CXL), Veriflex IOL and ICL using the Corvis ST (Oculus) andEndocthelial cell Density . A total of 90 patients will be recruited from the ClearVision Laser Center database between January 2025 and December 2025. Participants will undergo non-contact biomechanical assessments at multiple postoperative time points to track corneal stability and elasticity over time.
Data Collection \& Measurements Patient demographics, clinical history, and baseline preoperative data, including corneal thickness (pachymetry) and refractive status, will be collected. The Corvis ST will be used to measure key biomechanical parameters, such as Corneal Deformation Amplitude (CDA), Applanation Times (A1T \& A2T), Radius of Curvature at Highest Concavity (RHC), Stiffness Parameter (SP-A1), Integrated Radius (IR), and the Corvis Biomechanical Index (CBI).
Measurement Protocol
All measurements will be conducted in a controlled environment with stable room temperature and humidity. Patients will be properly aligned, and three consecutive measurements per eye will be taken to ensure repeatability. Data will be recorded at specific intervals:
LASIK \& PRK: 1 month, 3 months, 6 months, and 12 months CXL: 1 month, 3 months, 6 months, 12 months, and 24 months Veriflex and ICL : 1 month, 3 months, 6 months, 12 months, Potential Benefits \& Risks The study aims to provide valuable insights into corneal biomechanical stability post-surgery, improving postoperative management and long-term visual outcomes. Risks are minimal, with only transient discomfort associated with the non-invasive Corvis ST measurements.
This study will contribute to a better understanding of corneal biomechanics in refractive and therapeutic procedures, potentially guiding future surgical decisions and patient care strategies.
- Conditions
- Myopia, Keratoconus, Refractive Surgery
- Being tested
- Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICL
- Keywords
- corneal biomechanics, prk, lasik, cxl
- Medical subject headings
- Myopia, Keratoconus
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICLOther
corneal biomechanics measurment using corvis St and corneal endothelial cell counts
| Study group | Role | What they receive |
|---|---|---|
| Lasik | a non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. Receives: Other: Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICL | |
| PRK | a non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. Receives: Other: Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICL | |
| CXL | a non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. Receives: Other: Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICL | |
| Veriflex and ICL | corneal Biomechanics and ECD measuments pre and postoperative . a non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. |
What is being measured
The primary outcome is the main question the study is designed to answer.
corneal biomechanics
Measured: 6 month
ECD measuments
corneal endothelial cell count measurments
Measured: Preoperative and 6 month postoperative
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Feb 2025
- Study start1 Jan 2025
- Primary completion28 Jun 2025
- Study completion31 Oct 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for MyopiaStudies of the same condition, open and under way.
- 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
- Prospective
- Enrolment
- 150 participants (actual)
Sponsor and investigators
- Lead sponsor
- Beni-Suef University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Mohamed Yasser Sayed Saif, Beni-Suef University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06818461
- Sponsor's protocol ID
- FMBSUREC/05012025/ Saif
- Status last verified
- Jul 2026
- First submitted
- 5 Feb 2025
- Last updated
- 2 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Publications
Saif PS, Okasha MG, Mahmoud H, Samir A, Abdelmonagy Ibrahim M. Impact of veriflex and ICL on corneal biomechanics and endothelial cell density. Sci Rep. 2025 Aug 27;15(1):31553. doi: 10.1038/s41598-025-14330-3.
PubMed 40866426Saif PS, Saif MYS, Abdel Dayem HMK, Elsayed MOA, Ibrahim MAM. Assessment of corneal biomechanical properties using Corvis ST following LASIK, PRK, and CXL. Lasers Med Sci. 2026 Apr 16;41(1):73. doi: 10.1007/s10103-026-04858-9.
PubMed 41986537Luce DA. Determining in vivo biomechanical properties of the cornea with an ocular response analyzer. J Cataract Refract Surg. 2005 Jan;31(1):156-62. doi: 10.1016/j.jcrs.2004.10.044.
PubMed 15721708
Study at a glance
From the registry record, last updated by the sponsor on 2 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Assessment of Corneal Biomechanical Properties Using Corvis ST and ECD Following LASIK, PRK, CXL, Veriflex IOL and Implantable Collamer Lens
- ClinicalTrials.gov ID
- NCT06818461
- Acronym / sponsor ID
- FMBSUREC/05012025/ Saif
- Conditions
- Myopia, Keratoconus, Refractive Surgery
- Keywords
- corneal biomechanics, prk, lasik, cxl
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 150 participants (actual)
- Lead sponsor
- Beni-Suef UniversityUniversity, hospital or other
- Study start
- 1 Jan 2025 (actual)
- Primary completion
- 28 Jun 2025 (actual)
- Study completion
- 31 Oct 2025 (actual)
- First posted
- 10 Feb 2025 (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.
To evaluate corneal biomechanical changes using the Corvis ST and ECD in patients who have under-gone LASIK, PRK, corneal cross-linking (CXL), Veriflex IOL and ICL.
Detailed description
This observational study aims to evaluate corneal biomechanical changes and ECD in patients who have undergone LASIK, PRK, corneal cross-linking (CXL), Veriflex IOL and ICL using the Corvis ST (Oculus) andEndocthelial cell Density . A total of 90 patients will be recruited from the ClearVision Laser Center database between January 2025 and December 2025. Participants will undergo non-contact biomechanical assessments at multiple postoperative time points to track corneal stability and elasticity over time.
Data Collection \& Measurements Patient demographics, clinical history, and baseline preoperative data, including corneal thickness (pachymetry) and refractive status, will be collected. The Corvis ST will be used to measure key biomechanical parameters, such as Corneal Deformation Amplitude (CDA), Applanation Times (A1T \& A2T), Radius of Curvature at Highest Concavity (RHC), Stiffness Parameter (SP-A1), Integrated Radius (IR), and the Corvis Biomechanical Index (CBI).
Measurement Protocol
All measurements will be conducted in a controlled environment with stable room temperature and humidity. Patients will be properly aligned, and three consecutive measurements per eye will be taken to ensure repeatability. Data will be recorded at specific intervals:
LASIK \& PRK: 1 month, 3 months, 6 months, and 12 months CXL: 1 month, 3 months, 6 months, 12 months, and 24 months Veriflex and ICL : 1 month, 3 months, 6 months, 12 months, Potential Benefits \& Risks The study aims to provide valuable insights into corneal biomechanical stability post-surgery, improving postoperative management and long-term visual outcomes. Risks are minimal, with only transient discomfort associated with the non-invasive Corvis ST measurements.
This study will contribute to a better understanding of corneal biomechanics in refractive and therapeutic procedures, potentially guiding future surgical decisions and patient care strategies.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Lasik | – | Other: Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICLa non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. |
| PRK | – | Other: Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICLa non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. |
| CXL | – | Other: Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICLa non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. |
| Veriflex and ICL | – | –corneal Biomechanics and ECD measuments pre and postoperative . a non-contact air puff tonometer combined with Scheimpflug imaging to assess the cornea's deformation response. Measurements will be taken at multiple postoperative time points to track biomechanical changes. Key parameters such as Deformation Amplitude (DA), Stiffness Parameter (SP-A1), Applanation Times (A1 \& A2), Peak Distance (PD), and Biomechanically Corrected IOP (bIOP) will be recorded. |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- patients coming for refractive surgery
Key inclusion criteria (2 listed)
- 1. Adults aged 18-60 years. 2. Patients who have undergone LASIK, PRK, or CXL at least 1 month prior to measure-ment.
- 3. Stable refraction for at least 3 months post-procedure. 4. No evidence of active ocular disease or infection.
Key exclusion criteria (3 listed)
- 1. History of other ocular surgeries (excluding LASIK, PRK, or CXL). 2. Presence of keratoconus or other corneal ectatic disorders not treated with CXL.
- 3. Systemic or ocular conditions affecting corneal biomechanical properties (e.g., dia-betes, connective tissue disorders).
- 4. Current or recent use of medications influencing corneal biomechanics.
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 |
|---|---|---|
| Corvis St Before and after lasik, PRK, CXL, Veriflex IOL and ICLcorneal biomechanics measurment using corvis St and corneal endothelial cell counts | Other | CXL, Lasik, PRK |
Primary outcome
corneal biomechanics
Time frame: 6 month
ECD measuments
Time frame: Preoperative and 6 month postoperative
corneal endothelial cell count measurments
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 2 Jul 2026.
- Background: PubMed 40866426Saif PS, Okasha MG, Mahmoud H, Samir A, Abdelmonagy Ibrahim M. Impact of veriflex and ICL on corneal biomechanics and endothelial cell density. Sci Rep. 2025 Aug 27;15(1):31553. doi: 10.1038/s41598-025-14330-3.
- Background: PubMed 41986537Saif PS, Saif MYS, Abdel Dayem HMK, Elsayed MOA, Ibrahim MAM. Assessment of corneal biomechanical properties using Corvis ST following LASIK, PRK, and CXL. Lasers Med Sci. 2026 Apr 16;41(1):73. doi: 10.1007/s10103-026-04858-9.
- Background: PubMed 15721708Luce DA. Determining in vivo biomechanical properties of the cornea with an ocular response analyzer. J Cataract Refract Surg. 2005 Jan;31(1):156-62. doi: 10.1016/j.jcrs.2004.10.044.
- Individual participant dataSharing planned: Undecided
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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.
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 Myopia and Keratoconus, run by Beni-Suef University at 1 site in Egypt.
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 2 inclusion and 3 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 2 Jul 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 Egypt. 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?
corneal biomechanics (time frame: 6 month). The study lists 2 primary outcomes in all. 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 NCT06818461, which also lists 3 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 2 Jul 2026; AzTrials last refreshed its copy on 26 Oct 2026.