MRI Study of Subconjunctival and Intravitreal Injections

Li, S. Kevin; Hao, Jinsong; Liu, Hongshan; Lee, Jing‐Huei

doi:10.1002/jps.23127

Cited by 20 publications

(13 citation statements)

References 38 publications

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“…These images show that the cylindrical bolus approximation is quite good. For treating the vitreous as an infinite medium [item (b) above], a point source in a spherical shell of radius 2 cm was compared with a corresponding distribution for an infinite medium [Equation (11)]. Also compared were the case of a 2-mm radius spherical bolus in a finite medium with that for an infinite medium.…”

Section: Analytical Resultsmentioning

confidence: 99%

“…Figure 5: Contours of constant concentration of Gd-DTPA in the vitreous of the bovine eye. The continuous lines are the experimental results while the broken lines represent the theory according to Equation (11). The slight indentations seen in (b) are the needle marks due to the injection.…”

Section: Discussionmentioning

confidence: 99%

“…Over the last few decades, considerable progress has been made in the area of numerical modeling of ocular transport process [4,5,6,7,8,9,10]. On the experimental side, magnetic resonance imaging (MRI) has been particularly useful in providing insight into the transport processes following intravitreal injection [4,11,12]. For success in the numerical modeling effort, accurate measurement of the transport properties of the vitreous, particularly the diffusion coefficient, are fundamentally important, and this is the focus of the present review.…”

Section: Introductionmentioning

confidence: 99%

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Diffusive Transport in the Vitreous Humor: Experimental and Analytical Studies

Penkova

Moats

Humayun

et al. 2019

Journal of Heat Transfer

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In relation to intravitreal drug delivery, predictive mathematical models for drug transport are being developed, and to effectively implement these for retinal delivery, the information on biophysical properties of various ocular tissues is fundamentally important. It is therefore necessary to accurately measure the diffusion coefficient of drugs and drug surrogates in the vitreous humor. In this review, we present the studies conducted by various researchers on such measurements over the last several decades. These include imaging techniques (fluorescence and magnetic resonance imaging (MRI)) that make use of introducing a contrast agent or a labeled drug into the vitreous and tracking its diffusive movement at various time points. A predictive model for the same initial conditions when matched with the experimental measurements provides the diffusion coefficient, leading to results for various molecules ranging in size from approximately 0.1 to 160 kDa. For real drugs, the effectiveness of this system depends on the successful labeling of the drugs with suitable contrast agents such as fluorescein and gadolinium or manganese so that fluorescence or MR imagining could be conducted. Besides this technique, some work has been carried out using the diffusion apparatus for measuring permeation of a drug across an excised vitreous body from a donor chamber to the receptor by sampling assays from the chambers at various time intervals. This has the advantage of not requiring labeling but is otherwise more disruptive to the vitreous. Some success with nanoparticles has been achieved using dynamic light scattering (DLS), and presently, radioactive labeling is being explored.

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Section: Analytical Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diffusive Transport in the Vitreous Humor: Experimental and Analytical Studies

Penkova

Moats

Humayun

et al. 2019

Journal of Heat Transfer

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“…The vitreous humor acts as a natural depot, slowly releasing drug over ~1 month, depending on formulation[15, 16]. However, the drug diffuses isotropically through the vitreous and can thus diffuse towards non-target regions of the eye (e.g., lens and ciliary body), resulting in side effects[17–21]. An intact blood-retinal barrier can also impede the transport of drugs from the vitreous to the choroid and retinal pigment epithelium [8, 22].…”

Section: The Need For Novel Routes Of Administration To the Posterimentioning

confidence: 99%

The suprachoroidal space as a route of administration to the posterior segment of the eye

Chiang

Jung

Prausnitz

2018

Advanced Drug Delivery Reviews

102

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The suprachoroidal space (SCS) is a potential space between the sclera and choroid that traverses the circumference of the posterior segment of the eye. The SCS is an attractive site for drug delivery because it targets the choroid, retinal pigment epithelium, and retina with high bioavailability, while maintaining low levels elsewhere in the eye. Indeed, phase III clinical trials are investigating the safety and efficacy of SCS drug delivery. Here, we review the anatomy and physiology of the SCS; methods to access the SCS; kinetics of SCS drug delivery; strategies to target within the SCS; current and potential clinical indications; and the safety and efficacy of this approach in preclinical animal studies and clinical trials.

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“…Recently, MRI techniques have been applied to ophthalmology providing both structural and functional information in order to evaluate the therapeutic effectiveness, facilitate diagnosis and assist preoperative planning [10e16]. Moreover, MRI is a promising non-invasive method for ocular-drug delivery assessment [17,18].…”

Section: Introductionmentioning

confidence: 99%