TY - JOUR
T1 - Corneal stromal elasticity and viscoelasticity assessed by atomic force microscopy after different cross linking protocols
AU - Dias, Janice
AU - Diakonis, Vasilios F.
AU - Lorenzo, Michael
AU - Gonzalez, Felipe
AU - Porras, Kevin
AU - Douglas, Simone
AU - Avila, Marcel
AU - Yoo, Sonia H.
AU - Ziebarth, Noël M.
N1 - Funding Information:
UNCF/MERCK Science Research Dissertation Fellowship (JD); NIH National Research Service Award Individual Predoctoral Fellowship (1F31EY021714-01, JD); Hellenic Society of Intraocular Implants and Refractive Surgery scholarship for fellowship training (VFD).
PY - 2015/9/1
Y1 - 2015/9/1
N2 - The purpose of this study was to evaluate elasticity and viscoelasticity in the anterior and deeper stromal regions of the cornea after cross linking with three different protocols using atomic force microscopy (AFM) through indentation. A total of 40 porcine corneas were used in this study and were divided into 4 groups (10 corneas per group): control (no treatment), Dresden (corneal epithelial debridement, riboflavin pretreatment for 30min and a 3mw/cm2 for 30min UVA irradiation), accelerated (corneal epithelial debridement, riboflavin pretreatment for 30min and a 30mw/cm2 for 3min UVA irradiation), and genipin (corneal epithelial debridement and submersion of anterior surface in a 1% genipin solution for 4h). Elasticity and viscoelasticity were quantified using AFM through indentation for all corneas, for the anterior stroma and at a depth of 200μm. For the control, Dresden, accelerated, and genipin groups, respectively, the average Young's modulus for the anterior stromal region was 0.60±0.58MPa, 1.58±1.04MPa, 0.86±0.46MPa, and 1.71±0.51MPa; the average for the 200μm stromal depth was 0.08±0.06MPa, 0.08±0.04MPa, 0.08±0.04MPa, and 0.06±0.01MPa. Corneas crosslinked with the Dresden protocol and genipin were significantly stiffer than controls (p<0.05) in the anterior region only. For the control, Dresden, Accelerated, and genipin groups, respectively, the average calculated apparent viscosity for the anterior stroma was 88.2±43.7kPa-s, 8.3±7.1kPa-s, 8.1±2.3kPa-s, and 9.5±3.8kPa-s; the average for the 200μm stromal depth was 35.0±3.7kPa-s, 49.6±35.1kPa-s, 42.4±17.6kPa-s, and 41.8±37.6kPa-s. All crosslinking protocols resulted in a decrease in viscosity in the anterior region only (p<0.05). The effects of cross-linking seem to be limited to the anterior corneal stroma and do not extend to the deeper stromal region. Additionally, the Dresden and genipin protocols seem to produce a stiffer anterior corneal stroma when compared to the accelerated protocol.
AB - The purpose of this study was to evaluate elasticity and viscoelasticity in the anterior and deeper stromal regions of the cornea after cross linking with three different protocols using atomic force microscopy (AFM) through indentation. A total of 40 porcine corneas were used in this study and were divided into 4 groups (10 corneas per group): control (no treatment), Dresden (corneal epithelial debridement, riboflavin pretreatment for 30min and a 3mw/cm2 for 30min UVA irradiation), accelerated (corneal epithelial debridement, riboflavin pretreatment for 30min and a 30mw/cm2 for 3min UVA irradiation), and genipin (corneal epithelial debridement and submersion of anterior surface in a 1% genipin solution for 4h). Elasticity and viscoelasticity were quantified using AFM through indentation for all corneas, for the anterior stroma and at a depth of 200μm. For the control, Dresden, accelerated, and genipin groups, respectively, the average Young's modulus for the anterior stromal region was 0.60±0.58MPa, 1.58±1.04MPa, 0.86±0.46MPa, and 1.71±0.51MPa; the average for the 200μm stromal depth was 0.08±0.06MPa, 0.08±0.04MPa, 0.08±0.04MPa, and 0.06±0.01MPa. Corneas crosslinked with the Dresden protocol and genipin were significantly stiffer than controls (p<0.05) in the anterior region only. For the control, Dresden, Accelerated, and genipin groups, respectively, the average calculated apparent viscosity for the anterior stroma was 88.2±43.7kPa-s, 8.3±7.1kPa-s, 8.1±2.3kPa-s, and 9.5±3.8kPa-s; the average for the 200μm stromal depth was 35.0±3.7kPa-s, 49.6±35.1kPa-s, 42.4±17.6kPa-s, and 41.8±37.6kPa-s. All crosslinking protocols resulted in a decrease in viscosity in the anterior region only (p<0.05). The effects of cross-linking seem to be limited to the anterior corneal stroma and do not extend to the deeper stromal region. Additionally, the Dresden and genipin protocols seem to produce a stiffer anterior corneal stroma when compared to the accelerated protocol.
KW - Atomic force microscopy
KW - Cornea crosslinking
KW - Corneal elasticity
KW - Corneal viscoelasticity
KW - Ultraviolet light
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U2 - 10.1016/j.exer.2015.06.015
DO - 10.1016/j.exer.2015.06.015
M3 - Article
C2 - 26093276
AN - SCOPUS:84934970023
VL - 138
SP - 1
EP - 5
JO - Experimental Eye Research
JF - Experimental Eye Research
SN - 0014-4835
ER -