Machine-Made Sight

Donated eye tissue is a vital resource. Not only is it used to treat corneal conditions, but also to aid research into new sight-saving treatments. But, as with any organ supply, demand outstrips supply; in fact, for every 70 corneas needed, only one is available (1).

Several initiatives aim to increase the number of people consenting to eye tissue donation, but it seems likely we must also turn to technology and bioengineering to meet current and future needs. But what is the current state of bioengineering? And how close are we to – for example – 3D printing replacement eyes?

3D printing has taken the world by storm, finding applications across a variety of fields including art, engineering, and food sciences, so it’s no surprise that biomedical researchers are also exploring its benefits to healthcare. 3D bioprinting follows the principles of additive manufacturing, but instead of using plastics, liquids, or powder grains to build the structure, it uses bio-inks: a combination of cells obtained from patients and biopolymer gels. By depositing the bio-inks layer by layer, tissue-like structures can be generated.

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Though 3D printing is booming – it’s far from mature. Currently, the majority of 3D-printed parts are either non-functional models or parts that find their functionality when assembled together within a larger whole. And in the case of existing 3D bioprinting technology, printed structures are unable to match the granular complexity of the real deal.

And it’s fair to say the eye is not the easiest structure to replicate – both in terms of complexity and size. For one thing, the eye contains many different cell types in specific locations; to replicate such complexity, the 3D bioprinter would not only need bio-inks for each individual cell type, but also require extreme precision to ensure functionality.

Moreover, ophthalmic research is constantly broadening our understanding of the structure and function of the eye. Recent discoveries include a new class of retinal neuron and the mapping of the retinal pigment epithelium, which suggests there is yet more to discover. And we can’t accurately copy what we don’t know. Does that mean 3D printing parts of the eye is an impossible feat? Well, in the past decade, researchers have been able to bioprint human livers, kidneys, and skin (2). And although researchers are conservative in their estimates for how long it will be before fully functional 3D-printed organs can be implanted in humans, the 3D-printed eye does at least feel in the realms of distant possibility. But will 3D bioprinting beat bionics to the prize?

Do you have any thoughts or predictions about 3D bioprinting in the future of eye care? If so, please comment below or share with us: edit@theophthalmologist.com.