Factors influencing intraocular pressure in cultured human anterior segments

PURPOSE. To determine why variations in intraocular pressure (IOP) occur in cultured human anterior segments despite a constant rate of infusion of culture medium. Two types of variations occur: an initial elevation of IOP and small changes in baseline IOP. METHODS. Anterior segments from human eyes were placed in perfusion organ culture. In cultures with initially high IOP, eyes were fixed at the high IOP level and histologic examination performed. In other cultures with high initial IOP, effluent medium was collected and subsequently reinfused after IOP had decreased to baseline. In cultures with stable baseline IOP, cell fragments from monolayer-cultured cells, or human genomic DNA, were infused at concentrations equivalent to 30,000 to 300,000 cells. RESULTS. Electron microscopy of initially high-pressure cultures revealed scattered cell debris throughout the meshwork in greater amounts than found in eyes without initially high IOP. Reinfusion of effluent media from cultures with high initial pressures caused elevation of IOP. Centrifugation of effluent media lessened this elevation of IOP. In cultures with stable baseline IOP, infusion of cell fragments or genomic DNA raised IOP in a dose-dependent manner, with elevation of IOP for a minimum of 24 hours. CONCLUSIONS. Cell debris can elevate IOP during the initial culture period, and after baseline pressures are established. Cell fragments and DNA increase IOP in a dose-dependent manner. The variations in baseline IOP seen during culture are probably caused by cell fragments and debris from dying cells in the meshwork, ciliary body, and other anterior segment tissues.