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Determining vitreous viscosity using fluorescence recovery after photobleaching
Nishanthan Srikantha1,2, Yurema Teijeiro-Gonzalez3, Andrew Simpson1,2
1School of Medicine, King's College London, London, United Kingdom.
Plos One
|February 10, 2022
Summary
This study measured vitreous viscosity and macromolecular diffusion in porcine eyes using Fluorescence Recovery After Photobleaching (FRAP). FRAP is a viable method for assessing intravitreal diffusion and viscosity, crucial for drug delivery.
Area of Science:
- Ophthalmology
- Biophysics
- Biomaterials Science
Background:
- Vitreous humor composition influences its structure and function.
- Vitreous viscosity impacts intraocular drug delivery, distribution, and half-life.
- Porcine vitreous viscosity is considered a close analogue to human vitreous.
Purpose of the Study:
- To investigate vitreous viscosity and intravitreal macromolecular diffusion.
- To evaluate Fluorescence Recovery After Photobleaching (FRAP) as a method for measuring diffusion and viscosity.
- To determine the relevance of these parameters for drug delivery and elimination.
Main Methods:
- Utilized FRAP to measure intravitreal diffusion and viscosity in porcine eyes.
- Employed fluorescently labeled dextrans, ficolls, and bovine serum albumin (BSA) of varying molecular weights.
- Applied FRAP with different bleach area diameters.
Main Results:
- Determined mean porcine vitreous viscosity values: 3.54 ± 1.40 cP (dextran), 2.86 ± 1.13 cP (ficoll), and 4.54 ± 0.13 cP (BSA).
- Calculated an average porcine vitreous viscosity of 3.65 ± 0.60 cP.
- Demonstrated the inverse relationship between viscosity and diffusion.
Conclusions:
- FRAP is a feasible and practical optical method for quantifying macromolecular diffusion in the vitreous.
- This technique provides valuable insights into vitreous viscosity relevant to drug pharmacokinetics.
