PT  - JOURNAL ARTICLE
AU  - Yalong Dang
AU  - Susannah Waxman
AU  - Chao Wang
AU  - Ralitsa T. Loewen
AU  - Nils A. Loewen
TI  - Intraocular pressure elevation precedes a phagocytosis decline in a model of pigmentary glaucoma
AID  - 10.1101/175695
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 175695
4099  - http://biorxiv.org/content/early/2017/08/13/175695.short
4100  - http://biorxiv.org/content/early/2017/08/13/175695.full
AB  - Purpose Outflow regulation and phagocytosis are key functions of the trabecular meshwork (TM), but it is not clear how the two are related in secondary open angle glaucomas characterized by an increased particle load. We hypothesized that diminished TM phagocytosis is not the primary cause of early ocular hypertension and recreated pigment dispersion in a porcine ex vivo model.Materials and Methods Sixteen porcine anterior chamber cultures received a continuous infusion of pigment granules (P), while 16 additional anterior chambers served as controls (C). Pressure transducers recorded the intraocular pressure (IOP). The phagocytic capacity of the trabecular meshwork was determined by fluorescent microspheres.Results The baseline IOPs in P and C were similar (P=0.82). A significant IOP elevation occurred in P at 48, 120, and 180 hours (all P<0.01, compared to baseline). The pigment did not cause a reduction in TM phagocytosis at 48 hours, when the earliest IOP elevation occurred, but at 120 hours onward (P=0.001 compared to C). This reduction did not result in an additional IOP increase at 120 or 180 hours compared to the first IOP elevation at 48 hours (P>0.05).Conclusion In this porcine model of pigmentary glaucoma, an IOP elevation occurs much earlier than when phagocytosis fails, suggesting that two separate mechanisms might be at work.