Glaucoma could be called a silent destroyer of vision, because it generally produces no pressure, no pain, and, other than in exceptional circumstances where intraocular pressure (IOP) is tremendously elevated, no visual symptoms until irreversible damage has occurred.
It is estimated that glaucoma affects 1 in 200 people aged 50 years and younger, and 1 in 10 over age 80. In glaucoma, vision loss is the result of the death of retinal ganglion cells. Elevated IOP was typically used to define glaucoma in the past, however, as understanding of the glaucomatous disease process has advanced, other factors have been identified, with the concept of neuroprotection becoming increasingly important in the management of glaucoma.
IOP is determined by a delicate balance between the production of liquid aqueous humor and its drainage. Aqueous humor is produced by the ciliary body, flowing from there into the posterior chamber, and then through the pupil into the anterior chamber. From here the trabecular meshwork drains aqueous humor into general blood circulation via the scleral plexus.
While glaucoma is generally equated with elevated eye pressure, there is no way of knowing the level of IOP subjectively; it can only be determined accurately when specifically tested by the eye care professional during the course of an eye examination. Glaucoma does not primarily affect central vision; rather, it is characterized by defects in the peripheral field. Without detection and effective treatment, these peripheral field defects can progress until they eventually lead to a severe restriction of the visual field or directly affect fixation, so that the victim finally becomes aware that something is wrong. Any loss in vision is generally permanent and irreversible.
Once glaucoma has been diagnosed, there are many therapeutic options to help prevent subsequent loss of vision or of the field of vision. Correctly identifying glaucoma can present more of a challenge than actually treating the disease. This is why education to make individuals aware of the risk of glaucoma is so important and to encourage them to be tested is of such great importance. This is also why it is a special focus of the preventive medicine aspect of Healthy Sight Counseling.