Background
Low-tension glaucoma (LTG) is a chronic optic neuropathy that affects adults. Its features parallel primary open-angle glaucoma (POAG), including characteristic optic disc cupping and visual-field loss, with the exception of a consistently normal intraocular pressure (IOP), ie, less than 22 mm Hg. [1] Although the upper limit of "normal" is fuzzy and arbitrary, cases of low-tension glaucoma tend not to be with truly low pressures but rather with pressures considered to be in the moderate or upper-normal range, however "normal" is defined.
Pathophysiology
Low-tension glaucoma is an optic neuropathy with chronic loss of retinal ganglion cells (RGC) due to a genetic hypersensitivity to IOP. Low-tension glaucoma also is due to vascular factors, including vasospasm and ischemia.
Epidemiology
Frequency
United States
Up to 15-25% of patients with POAG experience low-tension glaucoma. According to the Baltimore Eye Study, 50% of individuals with glaucomatous disc and visual-field changes had an IOP of less than 21 mm Hg on a single visit, and 33% had an IOP of less than 21 mm Hg on 2 measurements.
International
The prevalence of low-tension glaucoma is higher in Japan and Korea. [2]
Mortality/Morbidity
Loss of peripheral vision is associated with low-tension glaucoma.
Race
The prevalence of low-tension glaucoma is higher in Japan and Korea. [2]
Sex
Low-tension glaucoma is more common in females than in males.
Age
The mean age of patients with low-tension glaucoma is 60 years; they typically are older than patients with POAG.
Patient Education
For excellent patient education resources, visit eMedicineHealth's Eye and Vision Center. Also, see eMedicineHealth's patient education articles Normal-Tension Glaucoma, Glaucoma Overview, Glaucoma FAQs, and Glaucoma Medications.
