Glaucoma is a group of diseases of the optic nerve involving loss of retinal ganglion cells in a characteristic pattern of optic neuropathy. Raised intraocular pressure is a significant risk factor for developing glaucoma. There is no set threshold for intraocular pressure that causes glaucoma — while one person may develop nerve damage at a relatively low pressure, another person may have high eye pressures for years and yet never develop damage. ...