Abstract
Purpose :
Scleral collagen crosslinking (SXL) has been proposed as a therapeutic treatment for prevention of progressive myopia. In this study, we compare the effects of Rose Bengal-Green Light (RGX) and Rivoflavin-UVA (UVX) crosslinking in scleral stiffening thought a hydration-stiffness correlation.
Methods :
35 eyes from adult New Zealand white rabbits (2.5-3.5 kg) were treated with either RGX (523nm 0.25W/cm2, 400s) or UVX (370nm, 3mW/cm2, 30min). Posterior nasal (NR) and temporal (TR) regions were crosslinked (24-48h post-mortem). One side of the globe was SXL and the other kept as control. Strips (3mmx20mm) were extracted and brought under hydration-tensile and tensile tests. In hydration-tensile tests, strips from control and treated regions were dehydrated (24h, room temperature), re-hydrated using 10uL/min phosphate-buffered saline solution (PBS) and mounted in a uniaxial stretcher (CellScale, Canada). In tensile tests, samples were mounted after extraction. Part of the specimens were immersed in PBS (n=54) and the rest kept in air (n=24) while subjected to a stress-recover test. The Young’s modulus (YM) was calculated between 0% and 12% strain and stress-strain curves were plotted as a derivate marker for SXL strength. T-test was used to test treatment and hydration-induced differences in scleral biomechanics.
Results :
RGX and UVX produced an increase in stiffness (115% and 296% (TR), respectively) compared with untreated sclera. At 8% strain, the YM of UVX samples was significantly higher than the untreated ones (16.11±0.94 vs 3.36±0.69MPa (TR), and 15.76±1.28 vs 3.15±0.49MPa (NR) P<0.001), and significantly higher than RGX samples (7.24±0.70MPa (TR) and 10.44±0.96MPa (NR) P<0.001). Tensile behavior is influenced by PBS immersion during the mechanical test. Control samples processed in air were twice (TR) and 1.5 times (NR) stiffer than ones in PBS (P<0.05). Hydration and stiffness are inversely correlated in TR (r=-0.6, P< 0.05) and directly correlated in NR (r=0.7, P< 0.05) for untreated and treated samples.
Conclusions :
Posterior scleral stiffening with RGX and UVX treatment in rabbit is affected by a combination of treatment, region, and hydration. These results provide a method for in vivo studies to determine the efficacy of SXL-induced stiffening to help treat myopia.
This is a 2021 ARVO Annual Meeting abstract.