Corneal Cross-Linking With Verteporfin and Nonthermal Laser Therapy

Area of Science:

• Ophthalmology
• Biomaterials Science
• Biomechanical Engineering

Background:

• Corneal biomechanical properties are crucial for maintaining ocular integrity.
• Standard corneal collagen cross-linking (CXL) enhances stiffness but involves ultraviolet light.
• Novel methods for corneal cross-linking are being explored to improve safety and efficacy.

Purpose of the Study:

• To evaluate the efficacy of verteporfin combined with nonthermal laser therapy (NTL) in increasing corneal mechanical stiffness.
• To assess the resistance of V+NTL treated corneas to enzymatic degradation ex vivo.
• To compare the biomechanical effects of V+NTL with standard riboflavin/UVA cross-linking (R+UVA).

Main Methods:

• Human corneas were divided into groups: verteporfin alone (V), NTL alone (NTL), V+NTL (1 or 6 sequences), R+UVA (positive control), and untreated (negative control).
• Corneas underwent enzymatic digestion, compression, creep, and tensile strength testing to measure biomechanical properties.
• V+NTL treatment involved 6 sequences of 1-minute NTL exposure at 689 nm.

Main Results:

• Corneas treated with V+NTL6 and R+UVA exhibited increased rigidity and curvature compared to controls.
• Stress-strain tests revealed significantly greater stiffness in V+NTL6 and R+UVA corneas (P < 0.005).
• V+NTL6 corneas showed a significantly lower creep rate and higher maximum stress values than untreated corneas (P < 0.05).

Conclusions:

• Verteporfin-NTL treatment (V+NTL6) effectively increases corneal mechanical stiffness and resistance to enzymatic collagenase degradation.
• The V+NTL6 protocol induces biomechanical changes in the cornea comparable to standard CXL.
• Further clinical investigation is warranted to confirm the therapeutic potential of V+NTL for corneal cross-linking.