Our eyeballs are round thanks to vitreous, a clear, gel-like substance that maintains the shape of the eye while allowing nutrients to circulate within it. As we age, vitreous may become increasingly liquefied, leading to shear stress in the eye and potential retinal detachment.
To treat disorders such as retinal detachment, the vitreous often has to be removed and replaced post-operatively by temporary substitutes such as an inert gas or silicone oil, which serve as a tamponade or packing agent. However, limitations of current replacement materials include poor vision, the need to adopt an uncomfortable head-down sleeping position for up to two weeks, restrictions on air travel and the need for additional surgeries to remove the vitreous substitutes.
Seeking to overcome such constraints, researchers led by Xinyi Su at A*STAR’s Institute of Molecular and Cell Biology (IMCB) and Xian Jun Loh at the Institute of Material Research Engineering (IMRE), together with colleagues at the National University of Singapore and the Singapore Eye Research Institute, developed a thermogel that could serve as a long-term vitreous substitute. The team used a polymer called EPC which is transparent at the body temperature of 37°C and has a similar refractive index to that of natural vitreous.
“This thermogel consists of low amounts of polymer which helps to improve the biocompatibility of the material, making it useful for biomedical applications,” said Loh.
“We demonstrated that a hydrogel comprising seven-weight-percent EPC (EPC-7%) is biocompatible in rabbit surgical models for up to six months. We also showed that it can function as an internal packing agent for retinal detachment repair surgery in non-human primates for up to one year,” added Su.
Being biodegradable, EPC-7% also has an edge over silicone oil as it does not require subsequent surgical removal. Importantly, when the hydrogel is broken down, it facilitates the formation of a vitreous-like body similar in protein composition to native vitreous in the eye.
The team is moving forward to commercialize the EPC-7% gel under the trade name Vitreogel, and intends to further test its application in humans. They are also exploring the use of Vitreogel as a sustained drug delivery platform for biologics to the posterior segment of the eye and as a scaffold to facilitate stem cell transplantation for retinal disease such as age-related macular degeneration.
“We have recently started a spin-off company called Vitreogel Innovations. We hope to obtain regulatory approval from the US Food and Drug Administration and CE marking in Europe before bringing Vitreogel to clinical trials within the next five years,” said Su.