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Related Experiment Video

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An Alternative and Validated Injection Method for Accessing the Subretinal Space via a Transcleral Posterior Approach

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Published on: December 7, 2016

The 1-Step Versus 2-Step Subretinal Injection Trial (1,2-SIT)-A Randomized Controlled Trial to Compare Drug Reflux

Matthew P Simunovic¹, Zak J Prime², Rhuen Chiou Chow²

¹From the Save Sight Institute (M.P.S. and L.K.T.), University of Sydney, Sydney, NSW, Australia; Sydney Eye Hospital (M.P.S., Z.J.P., R.C.C., E.H.S., Z.M., P.O., T.H.Y., K.T.O.), Sydney, NSW, Australia; Discipline of Surgery (M.P.S.), University of New South Wales, Sydney, Australia.

American Journal of Ophthalmology

|February 28, 2025

Summary

This summary is machine-generated.

This study found that both 1-step and 2-step subretinal injections (SRI) result in similar drug loss, but the 2-step method offers more consistent delivery. Sodium fluorescein is suitable for tracking gene and cell therapies in the subretinal space.

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Intraoperative Visualization of Subretinal Injection and Retinal Detachment in Rats

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Last Updated: May 24, 2025

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Published on: December 7, 2016

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Intraoperative Visualization of Subretinal Injection and Retinal Detachment in Rats

Intraoperative Visualization of Subretinal Injection and Retinal Detachment in Rats

Published on: March 7, 2025

Area of Science:

Ophthalmology
Retinal Surgery
Drug Delivery

Background:

Subretinal injection (SRI) is a key method for delivering therapies to the retina.
Estimating drug retention in the subretinal space is crucial for optimizing treatment efficacy.
Variability in drug delivery can impact outcomes in retinal gene and cell therapies.

Purpose of the Study:

To quantify drug retention in the subretinal space following 1-step versus 2-step SRI in human subjects.
To evaluate the impact of sodium fluorescein as an optical label on drug delivery consistency.
To assess the compatibility of sodium fluorescein with adeno-associated viral (AAV) vectors and retinal progenitor cells (RPCs).

Main Methods:

A randomized controlled trial comparing 1-step and 2-step SRI in patients with submacular hemorrhage.
Subretinal injection of tissue plasminogen activator with sodium fluorescein as an optical tracer.
Fluorophotometry to measure drug reflux and quantitative PCR/cell viability assays to assess AAV and RPCs.
Intravitreal anti-VEGF injections and follow-up for 12 weeks.

Main Results:

Mean drug reflux was comparable between 1-step (4.8%) and 2-step (3.9%) SRI, with no significant difference in surgical duration, visual acuity, or foveal thickness.
A significantly greater variability in drug reflux was observed with the 1-step SRI method.
Sodium fluorescein did not affect AAV titers or RPC viability in vitro.

Conclusions:

Drug loss following SRI ranged from 0.4% to 19.8%, with a mean of 4.3%.
The 2-step SRI approach provides more consistent drug delivery compared to the 1-step method.
Sodium fluorescein is a suitable agent for quantitatively tracking subretinal AAV gene and cell therapies.