Purpose:
We developed polymeric hydrogels as potential vitreous substitutes. Rheological testing was performed to compare the viscoelastic properties of the biomaterials to that of the central porcine vitreous.
Methods:
Hydrogels were prepared as previously described (Aliyar et al, Biomacromolecules, 6: 204–211, 2005). The mechanical properties of the porcine vitreous and hydrogels were determined using a Vilastic–3 oscillatory capillary tube rheometer (Austin, TX). The anterior segment was removed from fresh porcine eyes and the capillary was lowered into the center of the vitreous cavity and 0.4 cm3 was aspirated for testing. All samples were evaluated at 25oC at 2 Hz with increasing shear rate.
Results:
Both the porcine vitreous and 2% of the above hydrogel exhibited higher storage than loss moduli, indicating viscoelastic solid behavior. The hydrogel compared well with the porcine vitreous at low shear rates. At high shear rates, the porcine vitreous showed shear thinning and a change to more viscous than elastic behavior. The storage and loss moduli of the porcine vitreous and hydrogel are shown in the graph.
Conclusions:
The polyacrylamide hydrogel exhibited viscoelastic behavior similar to that of the porcine vitreous at low shear rates, indicating its potential as a vitreous substitute.
Keywords: vitreous substitutes • vitreous • retinal detachment