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Aysan Rangchian, Anibal Andres Francone, Matthew Farajzadeh, Helia Hosseini, Kelly Connelly, Jean-Pierre Hubschman, H. Pirouz Kavehpour; Effects of enzymes on the fluid properties of vitreous. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5712.
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© ARVO (1962-2015); The Authors (2016-present)
Effect of enzymes on the structure of vitreous is not fully understood. Rheological properties of the pig eye vitreous are used to study the effect of collagenase on the vitreous in comparison with the phosphate buffered saline (PBS) injection over a period of 24 hours.
Rheology is the study of flow under applied stress. A stress-controlled rheometer (AR 2000 TA instrument) is used in this experiment to run in-situ creep tests on the fresh pig eyes. Rheometer’s probe with 0.87 mm diameter enters the eye through a hole (about 5mm in diameter). The eyes are divided to two groups; the first group is injected with 50μL of collagenase type II (MP Biomedicals™ from Clostridium histolyticum) with the concentration of 0.7 mg/mL in isotonic PBS (N=17). The second group of eyes is injected with 50μL PBS solution (N=11).The characterization of vitreous is studied before the injection, one hour after the injection followed by a 24-hour test. Eyes are kept in the fridge and removed 1-hour before the experiment to preserve the freshness.
P-values confirm a significant decrease in the viscosity values and increase in the creep compliance intercept values in the group with collagenase injection. P-values for 24 hours comparison on the viscosity and creep compliance intercept between the collagenase group and PBS group are 8.296 e-7 and 1.27 e-5 respectively. P-values for 1-hour collagenase and PBS group are 1.638 e-5 and 0.01044. To confirm that the values of viscosity and creep compliance are not different between the two groups pre-injection, p-values are found to be 0.1217 for creep compliance intercept and 0.1929 for viscosity. Therefore, there are no statistically significant differences between the two groups before the injection.
Viscosity and creep compliance intercept show statistically significant changes. Supporting the hypothesis of the effect of collagenase in the network of vitreous in the eye. The results and the test method proposed in this abstract can be used to study the effect of drugs such as Ocriplasmin on the characteristics of vitreous.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Creep compliance intercept values measured of the vitreous before the injection of enzymes, 1-hour and 24-hour tests after injection with PBS or Collagenase type II
Viscosity of vitreous before the injection of enzymes, 1-hour and 24-hour tests after injection with PBS or Collagenase type II
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