Abstract
Purpose: :
To investigate the biomechanical effects of riboflavin/UVA corneal collagen crosslinking in the human eye as measured with an Optical Coherence Tomography (OCT)-based corneal elastography system.
Methods: :
A human donor globe was mounted beneath a custom OCT imaging device. The eye was infused to 15mmHg through an in-line pressure transducer and 21 Gauge needle. A gonioscopy lens attached to a micro-positioning stage imparted a displacement perturbation without distorting corneal curvature. OCT images were acquired through the gonioscopy lens before and after compression . Images were then processed to extract displacement information throughout the corneal stroma. 6 different regions of the cornea were then analyzed to quantify the magnitude, direction, and variability of local displacements. Measurements were performed on a single donor eye before and after applying riboflavin every 5min over a 30 minute duration and exposure to UV radiation(3mW/cm2) for the duration.
Results: :
Averaged across all 6 regions of interest in the cornea, the crosslinked cornea showed a displacement reduction of 46% in the lateral direction, and an average reduction of 0.4% in the axial direction. The anterior regions of the cornea showed a greater reduction in displacement at a value of 54.3% while the posterior region averaged a reduction of 39%. Additionally, we observed significantly lower standard deviations of the displacement in the cross linked cornea.
Conclusions: :
Crosslinking of the human cornea with a standard clinical protocol increased the resistance of the stroma to lateral/shear deformation in the presence of an axial displacement perturbation. This effect was seen throughout the corneal stroma, though the effect was more pronounced in the anterior than the posterior stroma. Spatially-resolved corneal elastography could be useful for quantifying the effect of clinical treatments of ectactic corneal disease and provides insight into the therapeutic mechanisms of collagen crosslinking.
Keywords: cornea: stroma and keratocytes • keratoconus • image processing