Posters

Corneal cross-linking with nonthermal laser therapy

Poster Details

First Author: S. Alageel UNITED STATES

Co Author(s):    j. ciolino                    

Abstract Details

Purpose:

To test if corneas treated with combined Verteporfin Nonthermal Laser Therapy increase corneal mechanical stiffness and increase resistance to enzymatic degradation.

Setting:

Human research corneas were obtained from Tissue Bank International (Baltimore, Maryland) and North Carolina Eye Bank (Winston-Salem, North Carolina). Riboflavin 5'-phosphate sodium salt hydrate, 20% (w/w) dextran solution (from Leuconostoc mesenteroides) and collagenase A (from Clostridium histolyticum, E.C. 3.4.24.3) were obtained from Sigma Aldrich (St. Louis, Missouri).

Methods:

Human corneas were fitted into Barron artificial anterior chambers, de-epithelialized. Corneas treated with Verteporfin alone, Irradiation with non-thermal laser (NTL), without verteporfin , and combined treatment verteporfin with non-Thermal Laser Therapy for one treatment sequence (V+NTL1) and six sequences protocol (V+NTL6). Other were pre-treated with 0.1% riboflavin/20% dextran for 30 minutes and irradiated with ultraviolet light type A (λ=370nm, irradiance= 3mW/cm2) for 30 minutes (R+UVA).To measure resistance to enzymatic degradation treated and untreated corneas were trephined and submerged in 0.3% collagenase .

Results:

On gross examination corneas treated by (V+NTL6) and (R+UVA) have more rigidity than untreated. Resistance to enzymatic digestion: Untreated corneas dissolved in collagenase A in 5.47h± 0.21 hours. Cross-linked corneas with R+UVA and V+NTL6 demonstrated a slower rate of dissolution than untreated (20.06h± ±1.23hours, 19.75 ± 0.95 hrs, p<0.005) Biomechanical Testing: 1.Compression Testing Corneas treated by R+UVA and V+NTL6 more stiff than untreated (0.70,0.80 vs. 0.43 MPa, p <0.05) 2.Creep Testing Corneas treated by V+NTL6 were found to have a significantly lower absolute creep rate than untreated corneas (-1.87 vs. -3.46, p < 0.05). 3.Tensile Testing the maximum stress was significantly higher for corneas that were treated with V+NTL6 and R+UVA than untreated corneas (15.17, 14.97 vs. 7.71, p < 0.05).

Conclusions:

we report for the first time that verteporfin non-thermal photodynamic laser increases corneal mechanical stiffness and resistance to enzymatic collagenase degradation. Although a clinical study of this methodology in human patients is still needed, our results suggest that verteporfin non-thermal photodynamic laser induces crosslinking cornea tissue that is similar to that of collagen crosslinking (CXL) using ultraviolet-A (UVA) irradiation combined with riboflavin. V-NLT could represent an alternative treatment for cornea ectatic diseases.

Financial Disclosure:

NONE