Magnetic resonance imaging studies of the volume of the rabbit eye with intravenous mannitol.

PURPOSE: Changes in the volume of rabbit eyes after intravenous mannitol injection were studied non-invasively using 3D-magnetic resonance imaging (MRI).

METHODS

Images of eight rabbit eyes were obtained using a 3D-gradient echo technique before and at 30, 60 and 90 minutes after mannitol injection at 4 g/kg. To evaluate the volume, the cross-sectional area of the eye in the central 5 slices was traced and totaled. The intraocular pressure (IOP) of five rabbits was measured before and after administration.

RESULTS

The total area of the eyeball decreased significantly at 60 minutes. The total area of the anterior chamber, iris plus ciliary body decreased rapidly and then recovered. The decrease in the vitreous and the IOP was consistently significant during the 90-minute observation period.

CONCLUSIONS

Consecutive MRIs enabled us to measure the changes in eye volume of the same rabbit before and after mannitol injection in a non-invasive manner.