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Cornea cross-linking with verteporfin non-thermal laser therapy

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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


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


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. 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)


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.


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).


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.

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