In a paper published by Nature Communications, a team of biomedical researchers and computer scientists unveiled a novel technique for 3D-printing prosthetic eyes that they claim offers a faster and reliable way compared to the current labor-intensive artisanal methods of crafting ocular prostheses.
Give me some background first.
Prosthetic eyes must fulfill several requirements in order to be utilized: they must fit, they must be comfortable, and they must meet the cosmetic expectations of the patient who will wear them.
Crafting ocular prostheses is a time-consuming process performed by highly skilled ocularists.
Case in point: It takes at least eight hours of labor to craft a custom prosthetic eye, according to the team behind the novel technique.
Now, talk about the technique.
This novel technique utilizes an anterior segment optical coherence tomography (AS-OCT) device with a color camera and LED lights to scan both the fellow eye (for color and veining accuracy) and to scan the eye socket after the patient is fitted with a conformer to provide a shape bias for the model.
The OCT scan data is then used in conjunction with a statistical shape model (SSM) to build the 3D model for the prosthesis.
But wait—can an OCT scan capture the entire socket?
Good catch! Because of the circular window, there’s a difference of up to 61% between the shape of a prosthetic eye and what the OCT can accurately measure.
That’s where predictive modeling comes in. The technique can also account for cases where a patient has an existing prosthesis that fits well and can be used as extra data for the correct shape of the new prosthesis.
What about aesthetics?
That’s where the color image of the fellow eye comes in. Several algorithms are run to reproduce the iris makeup, and a “procedurally generated veining network” runs to reproduce the sclera texture.
Wow. How long does it take to print one?
Six minutes! Then the prostheses are post-processed, which means tumbling to remove the 3D printer striations and the support materials, then hand-polishing, inspection, cleaning, and further inspection to ensure they’re safe for use.
Did any patients test out the 3D-printed prostheses?
Between November 2022 and April 2023, 10 patients received these prostheses.
Each prosthesis was fitted and further customized by an ocularist at Moorfields Eye Hospital NHS Foundation Trust (MEH) in London.
Two patients found the prostheses’ shapes “unacceptable,” while seven patients required their supplied prostheses to be adjusted during fitting. One patient rated all shapes as “excellent” and no adjustments were necessary.
What are the limitations of this technique?
The biggest limitation of this technique is that OCT data cannot be captured for patients with complex eye sockets. Additionally, scan data cannot be captured from patients with nystagmus or strabismus.
Take home.
A faster method for creating ocular prosthetics could increase consistency in prosthesis quality, access in remote areas, and potentially even allow for the creation of prosthetic eyes for those who were previously ineligible.