Controlled Subretinal Injection Pressure Prevents Damage in Pigs
Madeline Evers Olufsen1, Liva Spindler2, Nina Buus Sørensen2
1Department of Ophthalmology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark, madeline.evers.olufsen@regionh.dk.
Summary
Controlled subretinal injection at 24 PSI showed minimal retinal damage in pigs. This finding is crucial for safe gene and stem cell therapy delivery in retinal degenerative diseases.
Area of Science:
- Ophthalmology
- Regenerative Medicine
- Surgical Techniques
Background:
- Subretinal delivery is key for retinal gene and stem cell therapies.
- Manual injections may cause outer retinal damage due to high flow rates.
- Porcine models are used to study subretinal injection effects.
Purpose of the Study:
- Evaluate flow-related retinal damage from controlled subretinal injections.
- Determine optimal injection pressure for minimizing retinal damage.
- Assess the safety of different injection pressures in a porcine model.
Main Methods:
- In vitro flow rate estimation for a 41G cannula at varying pressures (6-48 PSI).
- Controlled subretinal injection of 300 μL balanced saline solution in 12 pigs at 14, 24, and 32 PSI.
- Ophthalmic examinations including multifocal electroretinogram (mfERG) and fundus photography, followed by histology.
Main Results:
- Flow shifts from laminar to turbulent at 32 PSI in vitro; manual injection flow is turbulent.
- Significant retinal pigment epithelium (RPE) damage observed, with highest damage at 32 PSI.
- Minimum retinal damage occurred at 24 PSI; no significant mfERG changes noted.
Conclusions:
- An injection pressure around 24 PSI appears safe for subretinal delivery.
- Retinal damage is linked to mechanical factors at low pressures and high flow at high pressures.
- Controlled 24 PSI subretinal injection minimizes mechanical and flow-related retinal damage in pigs.
