Purpose: Magnetic
resonance spectroscopy (MRS) can non-invasively measure metabolites in vivo in
healthy and diseased tissues. This technique is used to study the changes in
the lactate levels in vitreous humor of healthy vs. glaucoma eyes and to
correlate the lactate levels to severity of glaucoma.
Methods: A 3 inch
diameter surface coil receive and a body coil transmit assembly in a 1.5T MRI
scanner was used for this investigation. Prior to MRS, MR images were recorded
in the sagittal and axial planes. A 1 ml voxel was placed in the vitreous humor and the spectra were
recorded using the PRESS sequence with a CHESS sequence for water suppression.
Results: The seven
normal human volunteer eyes had a mean vitreous lactate concentration of 6.50
±0.29 mM (mean ±S.E.) with apparently little variation associated with age or
gender. The six eyes suspected of glaucoma or with early glaucoma had a mean
vitreous lactate
concentration of
10.89 ±1.43 mM (mean ±S.E.) with more variation than in normal eyes. The eight
eyes with advanced glaucoma had a mean vitreous lactate concentration of 16.78
±2.42 mM (mean ±S.E.) which was significantly higher and more variable than the
other two groups. These patients were judged as having advanced glaucoma based
upon their cup to disc ratios and visual field mean defects. There appeared to
be a positive correlation between vitreous lactate levels and visual field mean
defects.
Conclusion: Elevated
vitreous lactate levels may be associated with advancing glaucomatous optic
nerve damage.