A research team at Kyung Hee University Hospital at Gangdong has discovered that an enlarged pituitary tumor can cause vision loss by compressing the optic nerve crossing area.

The team, led by Professors Kang Ja-hun and Kim Tae-ki, found that headache (26.2 percent) was the most common symptom for patients who developed a pituitary tumor, followed by lactation secretion, menstrual impurity (17 percent), hypertrophic symptoms (13.7 percent) and visual impairment (12.4 percent).

According to a study conducted by the team, 54.4 percent of patients who had a pituitary tumor and underwent brain magnetic resonance imaging (MRI) showed an optic nerve crossing, while 43 percent of the patients showed visual impairment during a visual inspection.

Also, as the size of the pituitary tumor increased, the deterioration degree of visual loss and field grew significantly.

"The pituitary gland is a structure with a diameter of about 1.5 cm and is located where the optic nerve enters the back of the eye and meets the middle of the brain," Professor Kim said. "Due to the anatomic location, enlargement of the tumor may cause visual impairment as it can compress such optic nerve crossing."

Pituitary tumors have two classifications – nonfunctional and functional -- depending on whether they affect hormone secretion.

Nonfunctioning tumors can cause visual field depressions as the optic nerve can press the optic nerve narrowing the visual field as it grows larger in the brain. If neglected, it can ultimately cause total blindness.

"Treating the pituitary tumor can improve the decreased visual acuity and visual field," Kim said. "So it is better to treat the tumor before it gets larger."