Pressure difference between the anterior chamber and the vitreous cavity in eyes with pupillary block.

PURPOSE

The purpose of this study was to measure the pressure difference between the anterior chamber (AC) and the vitreous cavity (VC) in eyes with and without pupillary block.

MATERIALS AND METHODS

Seven vitrectomized porcine eyes were used. Infusion pressures of 10-80 mmHg were generated with a vented gas forced infusion system. Measurements of pressure were obtained with digital manometry connected to 25-gauge catheters from the AC and VC simultaneously. After increasing AC pressure to each target pressure, VC pressure was recorded, and vice versa. Inspection was performed with portable slit-lamp biomicroscopy to identify the development of pupillary block at the end of each experiment.

RESULTS

When the AC pressure was increased, the VC pressure obtained was similar to the AC pressure in all cases. When the VC pressure increased, the AC pressure obtained was similar to that at a VC pressure of less than 50 mmHg. When the VC pressure was increased rapidly to 60, 70, and 80 mmHg, the AC pressures obtained were 57.6 ± 1.0, 64.0 ± 0.8, and 69.6 ± 2.4 mmHg, respectively. Thus, the VC pressures obtained were 1.5, 5.9, and 9.1 mmHg higher than pressures obtained from AC with target pressures of 60, 70, and 80 mmHg, respectively (p = 0.027, 0.001, and 0.001, respectively). Pupillary block was observed in cases where the VC pressure was increased to more than 50 mmHg.

CONCLUSIONS

The AC pressure could be significantly lower than the VC pressure in some eyes with pupillary block.