[The ultrastructure changes of rabbit retina after periodical vacuum suction]

To study the effects of periodical vacuum-suction of different pressures on the ultrastructure of rabbits' retina.

Rabbits involved in the present study were divided into a control group and four treatment groups, which were treated with vacuum-suction of different pressures through scleral suction ring. The suction pressure was increased at a rate of 100 mm Hg/3 sec (1 mm Hg = 0.133 kPa) and reached (200 +/- 20) mm Hg (group I), (300 +/- 20) mm Hg (group II); (400 +/- 20) mm Hg (group III) and (500 +/- 20) mm Hg (group IV). The suction pressure was maintained for 5 seconds before released to zero. The corresponding intraocular pressure examined by Tonopen was 35 mm Hg, 45 mm Hg, 55 mm Hg and 75 mm Hg in these 4 groups, respectively. This circle was repeated for 10 times with 1 minute interval. The test was repeated every other day. The retina was examined by electron microscope after 2 weeks.

There was no obvious difference in the retina ultrastructure between the control group and group I. The retina ultrastructure changed slightly in group II which showed more active metabolism. Some significant changes were found in group III and group IV with cell necrosis in group IV.

Different elevations of intraocular pressure following periodical vacuum-suction have different effects on the retina of rabbit. Pressure less than 45 mm Hg has almost no effect, but some effects appear at 55 mm Hg pressure, and obviously damages are caused by 75 mm Hg pressure.