Biomechanical efficacy of corneal cross-linking using hypoosmolar riboflavin solution

Area of Science:

• Ophthalmology
• Biomaterials Science
• Corneal Biomechanics

Background:

• Corneal cross-linking strengthens the cornea by increasing biomechanical rigidity.
• Hypoosmolar riboflavin solutions are proposed for cross-linking thin corneas to mitigate stromal swelling.
• Standard corneal cross-linking uses isoosmolar riboflavin solutions.

Purpose of the Study:

• To compare the biomechanical efficacy of hypoosmolar dextran-free riboflavin solution corneal cross-linking (HCXL) versus standard isoosmolar corneal cross-linking (CXL).

Main Methods:

• Postmortem porcine eyes with debrided corneas were divided into control, isoosmolar CXL, and hypoosmolar HCXL groups.
• Samples underwent UVA irradiation (365 nm, 3 mW/cm², 30 min).
• Biomechanical properties were assessed using uniaxial stress-strain measurements on 400-µm anterior corneal flaps.

Main Results:

• Both isoosmolar CXL and hypoosmolar HCXL significantly increased corneal stress and Young's modulus compared to controls.
• No significant difference in biomechanical efficacy was observed between the isoosmolar and hypoosmolar groups.
• Histology confirmed no edema in the anterior 200 µm of corneas treated with the hypoosmolar solution.

Conclusions:

• Corneal cross-linking with either isoosmolar or hypoosmolar riboflavin solution yields comparable biomechanical outcomes.
• The anterior 200 µm of the cornea, where cross-linking is most effective, is not adversely affected by the swelling from hypoosmolar solutions.