Glaucoma in the far-sighted, who have smaller-than-normal anterior chambers, making physical contact between the iris and trabecular meshwork more likely. Normal-tension glaucoma (also "NTG", "low-tension glaucoma", "normal-pressure glaucoma") is a condition where the optic nerve is damaged although intraocular pressure (IOP) is in the normal range (12-22mm Hg). Individuals with a family history of NTG, those of Japanese ancestry, and those with a history of systemic heart disease are at higher than average risk of developing NTG. The cause of NTG is unknown. Secondary glaucoma refers to any case in which another disease, trauma, drug or procedure causes increased eye pressure,
Glaucoma valve drainage, such as iStent, CyPass, or Hydrus. A Cochrane Review of various aqueous shunts and modifications found that the Baerveldt implant may result in lower IOP than the Ahmed implant, but it was unclear if the difference in IOP reduction was clinically significant. The review suggests that practitioners should operate with the devices that they are most comfortable with, and have the most experience using. The glaucoma valve implant is indicated for glaucoma patients not responding to maximal medical therapy, with previous failed guarded filtering surgery (trabeculectomy) or in cases where conventional drainage surgery is unlikely to succeed. Common situations