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Updated: Aug 14, 2026
An Acute Retinal Model for Evaluating Blood Retinal Barrier Breach and Potential Drugs for Treatment
Published on: September 13, 2016
In vivo imaging of breakdown of the inner and outer blood-retinal barriers
H A Sen1, B A Berkowitz, N Ando
1Duke University Eye Center, Durham, North Carolina.
Abstract:
Real-time contrast-enhanced magnetic resonance imaging (MRI) was used to distinguish between experimentally induced breakdown of the vascular (inner) and retinal pigment epithelial (RPE; outer) blood-retinal barrier (BRB) in vivo. Pigmented rabbits were treated with intravenous sodium iodate 30 mg/kg, (a specific RPE cell poison), intravitreal N-ethylcarboxamidoadenosine (NECA) 10(-3) mol/l (which specifically disrupts the vascular BRB), or retinal diode laser photocoagulation. Coronal T1-weighted proton images were acquired in a timed sequence after intravenous injection of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA). Images were analyzed to localize leakage of Gd-DTPA and determine the permeability surface area product normalized per unit area (PS). The pattern of enhancement observed in eyes treated with sodium iodate differed clearly from that in eyes treated with NECA. PS' values were significantly higher in eyes treated with sodium iodate than with NECA. Simultaneous leakage from the outer and inner BRB in eyes treated with dense retinal laser photocoagulation could be localized and quantitated independently.
Insights
This study used real-time MRI to differentiate between inner and outer blood-retinal barrier (BRB) damage in rabbits. Contrast-enhanced MRI successfully distinguished between RPE and vascular BRB disruptions, aiding in diagnosis.
Area of Science:
- Ophthalmology
- Medical Imaging
- Physiology
Background:
- The blood-retinal barrier (BRB) comprises inner vascular and outer retinal pigment epithelial (RPE) layers.
- Distinguishing between disruptions in these two layers is crucial for understanding and treating retinal diseases.
- Current methods may lack the precision to differentiate localized BRB damage in vivo.
Purpose of the Study:
- To utilize real-time contrast-enhanced magnetic resonance imaging (MRI) to differentiate experimentally induced breakdown of the inner vascular and outer RPE blood-retinal barrier (BRB) in vivo.
- To quantify the permeability surface area product (PS) for each BRB component.
Main Methods:
- Real-time contrast-enhanced MRI (T1-weighted proton images) was employed in pigmented rabbits.
- Experimental models included sodium iodate (RPE poison), N-ethylcarboxamidoadenosine (NECA; vascular BRB disruptor), and diode laser photocoagulation.
- Gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) was injected intravenously, and leakage was analyzed to determine PS values.
Main Results:
- Distinct patterns of Gd-DTPA enhancement were observed between sodium iodate and NECA treatments, clearly differentiating RPE and vascular BRB damage.
- Permeability surface area product (PS') values were significantly higher in sodium iodate-treated eyes compared to NECA-treated eyes.
- Simultaneous inner and outer BRB leakage from laser photocoagulation was independently localized and quantified.
Conclusions:
- Real-time contrast-enhanced MRI is effective in distinguishing between inner and outer BRB breakdown in vivo.
- This technique allows for the independent localization and quantification of damage to the vascular and RPE components of the BRB.
- The findings support the use of advanced MRI techniques for diagnosing and studying BRB-related ocular conditions.
