SoR logo The Society of Rheology 79th Annual Meeting
October 7-11, 2007 - Salt Lake City, Utah
View Paper Info and Abstract


Poster Session

Optimized design of in situ forming vitreous substitutes

October 10, 2007 (Wednesday) 6:00

Poster Session / Grand Ballroom C

(Click on name to view author profile)

  1. Swindle, Katelyn E. (Washington University in St. Louis, Energy, Environmental, and Chemical Engineering)
  2. Dobson, Scott S. (Washington University in St. Louis, Biomedical Engineering)
  3. Ravi, Nathan (Washington University in St. Louis, Department of Veterans Affairs Medical Center)

(in printed abstract book)
Katelyn E. Swindle1, Scott S. Dobson2, and Nathan Ravi3
1Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63110; 2Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63110; 3Department of Veterans Affairs Medical Center, Washington University in St. Louis, St. Louis, MO

Swindle, Katelyn E.

Purpose: To use a statistically designed experimental plan for the development of a biomimetic hydrogel vitreous substitute that forms in situ under physiological conditions.

Methods: Various polyacrylamide hydrogel formulations were synthesized containing a reversible disulfide crosslinker and a hydrophobic comonomer. The hydrophobic comonomer, crosslinker, and hydrogel concentrations were varied. The concentration effects ascertained via preliminary testing were used to design an optimal formulation with viscoelastic and refractive properties similar to the natural vitreous humor. The values from natural porcine vitreous were used as a model for optimizing the hydrogel formulation. The storage and loss moduli of the hydrogels were determined using a Vilastic 3 capillary rheometer (Houston, TX) holding frequency or shear rate constant. The refractive indices of the hydrogels were determined using an Abbe refractometer.

Results: The optimal formulation’s viscoelasticity and refractive index were very similar to those of the natural young porcine vitreous. The polymer concentration in the hydrogel had the greatest effect on the viscoelastic properties while the hydrophobic monomer concentration had the least significant effect. Additionally, the variations in the hydrogel composition impacted the viscoelastic properties more significantly than the refractive indices.

Conclusions: The porcine vitreous is a loosely formed viscoelastic biological hydrogel with low storage and loss moduli. We therefore hypothesize that generating a synthetic hydrogel that acts as a viscoelastic solid will be more capable of dampening eye oscillations and tamponading the retina. Preliminary studies in vivo in rabbits have indicated that this hydrogel is extremely biocompatible. Matching the viscoelastic and refractive properties while maintaining this biocompatibility will allow rapid clinical development of an artificial vitreous substitute.