Glaucoma affects 1.2 million people in the United States alone, and it also accounts for 11% of blindness. In addition, 10 million people may have elevated intraocular pressure called "ocular-hypertension". These people show no demonstrable evidence of optic nerve damage, however, some may develop glaucoma. A research grant is being requested to develop a test for the detection of early visual loss in patients with ocular hypertension. It is not known with certainty whether an individual with statistically abnormal increased intra-ocular pressure (IOP) represents an early glaucoma or an ocular hypertensive patient. Furthermore, recent studies have shown that a large number of nerve fibers can already be lost in patients with normal visual fields. Thus, newer methods for the early detection of nerve damage must be pursued. The investigation will focus on determining whether spectral sensitivity measurements of the blue cone system can be used in the detection of early glaucomatous damage. The test is based on the fact that, in glaucoma, the blue cone response diminishes very early in the disease process. Thus, the study proposes to use a very sensitive test that takes advantage of this anomaly. The proposed test consists of selectively depressing the sensitivities of one or two cone mechanisms, in order to obtain the spectral sensitivity of the remaining mechanism. From this test, one can obtain the cone system that has been affected and the extent of the loss can be computed. To accomplish this task, measurements of spectral sensitivity function of the blue cone mechanism intra-ocular pressure, visual fields, lens absorption, macular pigment absorption, pupullary diameter, cup to disc ratio, acuity, and a fundus examination will be performed for a large group of normal subjects, ocular hypertensives, and early glaucoma patients. The measurements will reveal at what stage of the disease process the loss of blue cone sensitivity can be detected and monitor the progression of the disease process. Also, a relationship between field loss, intra-ocular pressure, and loss in blue cone sensitivity will be established. It is anticipated that this extensive study will confirm the preliminary data that the loss in blue cone sensitivity occurs very early in the disease process and will result in a very sensitive test to predict early glaucomatous damage in ocular hypertensive patients.