Flow-pressure relationship in perfusion studies of the living primate eye

Anterior chamber constant rate perfusion studies were performed in normal living monkey eyes. On careful inspection, the IOP-flow relation was seen to consist of a three stage curve. In the low range of infusions (0-6 microliters/min) IOP raised linearly. In the middle range (6-12 microliters/min) it remained almost constant and raised, again with high infusion rates (12-25 microliters/min). Calculating outflow facility from this pressure-flow relationship, it was shown that C value was constant in the low infusion range, increased in the middle range and decreased slowly over the high infusion rate range. A comparison was made with a similar curve derived from flow of fluids through non completely collapsible tubes. The change of IOP following high infusion rates consisted of a decrease in the steady-state pressures achieved. Comparison with formerly observed close phenomena was made and some thoughts about possible causes were brought.