A: The USDA created the Plant Hardiness Zone Map to help gardeners select plants that will survive in their particular climate zone. The zones are based on the average annual lowest winter temperature in a location, and each numeric zone spans 10 degrees (F) and is further divided into 5-degree âaâ and âbâ sections.
Secondary Glaucoma. Secondary glaucoma is often a side effect of injury or another eye condition, such as cataract or eye tumors. Medicines, such as corticosteroids, may also cause this type of glaucoma. Rarely, eye surgery can cause secondary glaucoma.laucoma is not a singular eye disease, but is instead a term for several eye conditions that can damage your optic nerve. The optic nerve is the nerve that supplies visual information to your brain from your eyes. Glaucoma is usually (but not always) the result of abnormally high pressure inside the eye.
1 Like POAG, normal-tension glaucoma (also called normal-pressure glaucoma, low-tension glaucoma or low-pressure glaucoma) is a type of open-angle glaucoma that can cause visual field loss due to optic nerve damage. 2  But in normal-tension glaucoma, the eye's IOP remains in the normal range. The cause of normal-tension glaucoma is not known. 2  But many doctors believe it is related to poor blood flow to the optic nerve. 3  Normal-tension glaucoma is more common in those who are Japanese, are female and/or have a history of vascular disease.