Cornea cross-linking with verteporfin non-thermal laser therapy

Session Details

Session Title: Presented Poster Session 16: Small Incision Lenticule Extraction

Session Date/Time: Monday 15/09/2014 | 15:00-17:00

Paper Time: 15:15

Venue: Pod 1 (Poster Village)

First Author: : S.Alageel SAUDI ARABIA

Co Author(s): :                  

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). Barron® artificial anterior chambers were purchased from Katena Eye Instruments (Denville, New Jersey). The VEGA LED-based UV emitter was purchased from Costruzione Strumenti Oftalmici (Firenze, Italy)

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 A solution at 37 degrees Celsius rotating at 150 rpm. The times to dissolution of the corneas were measured. The biomechanical properties were measured using Stress-strain measurements with compression using a Q800 DMA (TA instruments) , tensile using a Shimadzu AGS-X load frame, and Creep Testing.

Results:

Untreated corneas dissolved in collagenase A in 5.47h± 0.21 hours. Cross-linked corneas demonstrated a slower rate of dissolution (20.06h± ±1.23hours, p<0.005). Corneas treated with Verteporfin only or PDT alone showed or combined treatment for one sequence similar resistances to degradation as untreated corneas and did not increase resistance (5.95h ±0.33, 5.71± 0.375, 5.96±0.95 hours vs 5.47± 0.21 hours). Combined treatment for six sequences with intervals of balanced salt solution hydration with additional instillation of one drop of Verteporfin per sequence demonstrated a slower rate of dissolution (19.15 ± 0.21 hours, p<0.005). The stress strain tests showed that V- PDT and UVA groups stiffer than control( p<0.005). Interestingly the V-PDT group appears to be slightly stiffer than UVA group (although this difference is not statistically significant).

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.