Many people believe that the main effect of glaucoma on eye pressure is that it is increased, but current information suggests that this is just one of a few factors. In most cases of glaucoma, the eye pressure is, in fact, raised, but some types of this eye condition occur with normal eyeball pressure. For example, low-tension glaucoma occurs in patients without increased eye pressure, which means that high eye pressure is not the only indicator of this condition. In fact, the only sure symptoms of this issue include optic nerve damage and at least some vision loss.
In many cases, the effect of glaucoma on eye pressure is a measurable increase in intraocular pressure. This can be checked at eye exams with a tonometer, and if high eye pressure is detected, the eye doctor will look for other symptoms of glaucoma. If neither nerve damage or vision loss is detected, the patient may be diagnosed with ocular hypertension rather than glaucoma. Some patients can have high eye pressure without having any further issues because their optic nerve can withstand it, while other patients may have more sensitive optic nerves that do not require increased pressure to develop glaucoma. Thus, while the effect of glaucoma on eye pressure is typically an increase in tension, this is not always required to diagnose the issue.
Low-tension glaucoma, also referred to as normal tension, occurs when the eyeball pressure is within the normal range. Unfortunately, the same optic nerve damage usually occurs in patients with low tension as those with high tension, which is why considering the change by glaucoma on eye pressure alone is not usually a reliable way to diagnose the issue. Since a tonometer would find only normal pressure, other tests have to be used to diagnose this condition, such as visual field tests to screen for vision loss. An ophthalmoscope is often also used by eye doctors to get a glimpse of the optic nerve through the pupil, using the light from this instrument to check for damage.
There are some risk factors for glaucoma other than elevated intraocular pressure, allowing eye doctors to know which patients in particular should be screened. Age is one of the most well-known factors, as every year over 50 tends to put patients at a higher risk of developing this condition. Being nearsighted, having diabetes or hypertension, and having had eye surgery in the past can also increase the chances of glaucoma. Males, those of African descent, and anyone with a family history of glaucoma are all at higher risk of getting this condition, as well. Clearly, although the common effect of glaucoma on eye pressure is increased intraocular tension, there are various other risk factors, and symptoms to consider.