Clinical trial NCT06818461: Assessment of Corneal Biomechanical Properties Using Corvis ST Following LASIK, PRK, and CXL
Official title: Assessment of Corneal Biomechanical Properties Using Corvis ST Following LASIK, PRK, and CXL
Study type: OBSERVATIONAL
Overall status: ACTIVE_NOT_RECRUITING
Conditions: Myopia
Keratoconus
Refractive Surgery
Keywords: corneal biomechanics
prk
lasik
cxl
Lead sponsor: Beni-Suef University
Sponsor class: OTHER
First posted: 2025-02-10
Enrollment: 150
Sex: ALL
Minimum age (years): 18
Maximum age (years): 60
Standard ages: ADULT
Accepts healthy volunteers: yes
Observational model: CASE_CONTROL
Time perspective: PROSPECTIVE
Sampling method: PROBABILITY_SAMPLE
Study population: patients coming for refractive surgery

Brief summary: To evaluate corneal biomechanical changes using the Corvis ST in patients who have under-gone LASIK, PRK, and corneal cross-linking (CXL).

Detailed description: This observational study aims to evaluate corneal biomechanical changes in patients who have undergone LASIK, PRK, and corneal cross-linking (CXL) using the Corvis ST (Oculus). 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 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.

Eligibility criteria: Inclusion Criteria:

- 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.

Exclusion Criteria:

* 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.

Primary outcomes:
measure: corneal biomechanics
timeFrame: 6 month
Secondary outcomes:
Other outcomes:
Locations:
city: Mohandessin
country: Egypt
facility: Clearvision
state: Giza
Study officials:
References:
citation: Luce 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.