Glaucoma is a disease of the eye’s optic nerve. Glaucoma can result in the gradual loss of peripheral vision
resulting in tunnel vision and ultimately blindness. Usually, the damage to the optic nerve is caused by
increased pressure within the eye, which results from greater production than outflow of the fluid of the eye
(the aqueous humor). The normal intraocular pressure (IOP) is about 10 to 21 mm Hg. In chronic glaucoma,
the intraocular pressure is usually mildly to moderately elevated (22 to 40 mm Hg). In acute glaucoma, the
intraocular pressure is greater than 40 mm Hg.
In some cases glaucoma develops in people with normal IOP. Referred to as low-tension glaucoma or
normotensive glaucoma, this form accounts for approximately 25 to 30 percent of all glaucoma cases in
the United States.
Causes of Normotensive Glaucoma
Since elevated IOP is not a factor in normal-tension glaucoma, other factors are responsible for the optic
nerve damage. Suggested causes include:
• Reduced blood flow
• E arly nerve cell death
• Nerve irritation
• E xcess glutamate production
• A utoimmune disease
The condition is more common in women than in men and affects adults averaging 60 years old. A
common risk factor for normal-tension glaucoma is low blood pressure.
To evaluate the effect of oral magnesium therapy on ocular blood flow and visual field perimetry indices
in patients with normotensive glaucoma (NTG) 15 patients with NTG (study group) received 300 mg oral
magnesium (citrate) for 1 month, while 15 patients with NTG (control group) received no treatment. In
the study group, significant improvements were noted in visual field measurements, e.g., mean deviation
improved from -3.7 at baseline to -2.5 and pattern standard deviation improved from 3.6 baseline to 2.8.
There was no change in ocular blood flow, so the exact mechanism of magnesium’s effect is not known.