Microbead Model of Occlusion

Intraocular pressure (IOP) is highly regulated and can result in the development of glaucoma, uveitis, and retinal detachment when disturbed.¹ This important equilibrium of pressure is maintained through the production and drainage of aqueous humor through the trabecular meshwork (TM). The microbead occlusion model involves the administration of microbeads into the anterior chamber with pinpoint accuracy, which blocks the drainage channels within the TM. Successful blockage and elevated IOP are monitored and confirmed through a variety of advanced ocular imaging and data collection techniques. This data, combined with our biomarker analysis capabilities, can be used to better understand the effectiveness of various therapeutic candidates.

Figure 1. Polystyrene microbeads, administered into the anterior chamber of the eye, block drainage of aqueous humor through the trabecular meshwork, resulting in elevated intraocular pressure and injury to the cells of the retina.

Figure 2. Intraocular pressure is elevated in the weeks following intracameral injection of polystyrene microbeads as compared to contralateral and naive eyes.

Figure 3. Positive scotopic threshold response (pSTR) results demonstrate a decrease in RGC response 15 days following induction (n = 12).

Figure 4. Elevated intraocular pressure following microbead administration leads to the loss of retinal ganglion cells and robust increases in microglial activation, as illustrated through immunostaining of whole-mount retinas for Brn3a and Iba-1.

Reference:

• Machiele R, Motlagh M, Patel BC. Intraocular Pressure. [Updated 2022 Jul 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532237/

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