Intraocular Injection Device
Developing an Injection Device for Trials
The creation of an intraocular injection device capable of timed drug release to prevent an injection at high velocity that may potentially travel through the vitreous humor and damage the retina. After generating a functioning set of devices, they were used in a formative trial with changes implemented in preparation for clinical trials and manufacturing.
Additional Info
With a timed release system to slowly and safely dispense inserts into the eye, there were various problems encountered throughout the development of the intraocular injection device while generating a functioning set of formative devices. Additional details regarding each challenge, and the solution that followed, may be found below with accompanying content.
Challenges in Development
Drag Mechanism
To achieve the timed dose, the drag mechanism initially revolved around a spring-propelled push rod attached to a wire that would be drawn through a curved path as shown in the image. This method, in theory, would slow the speed of the push rod due to the interference built into the path; however, this was not the case and resulted in racking and inconsistent dosages. In order to combat this issue, the drag mechanism was switched to an oil-filled rotary damper to provide the resistance needed in a more reliable form factor. The housing was then modified and the release time could be further refined with these improvements.
Insert Adhesion
Another problem that surfaced throughout the testing of the device, specifically during the benchtop testing phase of the project, was the adhesion of inserts to one another. With each insert adhering to the following one, this would essentially create a spear-like formation that would travel through the vitreous humor and damage the retina. To counteract this issue, the client was notified and both the testing and coating formulation were adjusted in order to prevent the adhesion of these inserts. In regard to testing, the cannula being utilized would be cleaned with isopropyl alcohol between each use in order to limit the exposure of the inserts to remaining moisture. Additionally, a new membrane was selected with a softer durometer with the hopes of emulating the skin and once again preventing additional exposure to moisture.
