A framework for modeling ocular drug transport and flow through the eye using micro-CT

Area of Science:

• Ophthalmology
• Biomedical Imaging
• Pharmacokinetics

Background:

• Understanding ocular drug transport is crucial for effective treatment delivery.
• Intravitreal injections are a common route for delivering drugs to the posterior segment of the eye.
• Accurate methods are needed to assess drug distribution and concentration in real-time.

Purpose of the Study:

• To assess the concentration and transport mechanisms of ocular drug surrogates.
• To evaluate the utility of micro-computed tomography (micro-CT) for tracking intravitreal injections.
• To quantify diffusion coefficients and understand the movement of injected substances within the eye.

Main Methods:

• Enucleated porcine eyes were injected with an iodinated contrast agent.
• Micro-computed tomography (micro-CT) was used for imaging over 192 minutes.
• Image analysis involved signal profiles and regions of interest to determine iodine concentration; diffusion coefficients were calculated using nonlinear regression.

Main Results:

• A predominantly diffusive component was observed in contrast agent movement towards the back of the eye.
• Retinal fate of the contrast was observed within 120 minutes.
• Calculated diffusion coefficients varied with iodine concentration and decayed over time as the diffusion front interacted with the retinal wall.

Conclusions:

• Micro-CT provides a real-time, accurate, and non-invasive method for tracking intravitreal injection boluses and their concentration.
• The study demonstrates the feasibility of using micro-CT to investigate ocular drug transport mechanisms.
• Findings contribute to a better understanding of drug diffusion dynamics within the eye.