Vitreous Wipe: A new test prototype

Vitreous Wipe: A new test prototype

Lucas, Valentin (TU Delft Mechanical, Maritime and Materials Engineering)

Dodou, D. (mentor)
Breedveld, P. (mentor)
van Overdam, K. (graduation committee)
Sakes, A. (graduation committee)

Delft University of Technology

2022-07-29

Retinal detachment occurs when liquid slips behind the retina and does not allow the latter to lay flat on the posterior region of the eye. It alters the vision of the patient, hence requiring surgery to be corrected. In some cases, retinal detachment can occur after the retina has been treated for other pathologies.
Indeed, more than 20% of highly myopic patients who have been treated for retinal diseases are subject to retinal detachment a few months after the surgery and are required to undergo a second surgery. It is believed that a membrane, also called Vitreous Cortex Remnants (VCR), that arises due to vitreoschisis,
a retinal disease, is the reason for the re-detachment. VCR is often not dealt with during surgery because its removal is time-costly, the VCR is not well visible and instruments are not optimally adapted for removing VCR. The work aims to develop and experimentally evaluate new methods of removing VCR. For that purpose, a series of test prototypes were manufactured, and three surgeons assessed the efficiency of the prototypes for removing VCR from dissected pig’s eyes. Each eye was treated pre-experimentally according to a new model that tries to recreate vitreoschisis in a young porcine eye. The efficiency of each test prototype was assessed based on the force that the instrument tip exerted on
the pig’s retina, the number of strokes taken to remove the VCR completely, the tissue damage and the time used. Furthermore, the optimal tip length was determined based on the surgeons’ feedback. The results show that the force greatly depended on the stiffness of the instrument tip and that the most efficient prototype consisted of a PVA wipe cut to size 6x1x1 mm and a 0.1 mm diameter Nitinol wire. The prototype exerted a maximum force of 0.68 gr. The number of strokes was around 40, and the optimal tip length was just under 4.5 mm. While the experiments showed that it is a promising design, the tip needs to be remodeled to comply with the low stiffness needed and to be able to fit within a 23 gauge tube.

Retina
Vitreoschisis
Test prototype
Wiping
Eye

http://resolver.tudelft.nl/uuid:77aabdea-022a-4362-ac44-e796a0baf233

Student theses

master thesis

© 2022 Valentin Lucas