Eye pressure, scientifically known as intraocular pressure (IOP), is a measurement of the fluid pressure inside the eye. Maintaining a balanced IOP is important for overall eye health and the preservation of vision. This internal pressure helps the eye maintain its spherical shape, allowing light to focus properly onto the retina.
Understanding Eye Pressure
Eye pressure is regulated by a clear, watery fluid called aqueous humor, which fills the anterior and posterior chambers of the eye. The ciliary body, located in the posterior chamber, continuously produces this fluid. Aqueous humor provides nutrients and oxygen to various eye structures, such as the cornea and lens, which do not have a direct blood supply.
The fluid then flows through the pupil into the anterior chamber. From there, it drains out of the eye through a spongy tissue called the trabecular meshwork and into the bloodstream. A healthy balance between the production and drainage of aqueous humor maintains stable eye pressure. This pressure is measured in millimeters of mercury (mmHg).
Eye care professionals measure IOP using a test called tonometry, which involves gently flattening the cornea. Common methods include non-contact tonometry, which uses a puff of air, and applanation tonometry, where a probe lightly touches the eye surface.
Normal Ranges and Age-Related Changes
For most adults, a healthy eye pressure range is between 10 and 21 mmHg. Readings within this range indicate a balanced ocular system. However, individual variations are common, and a single reading may not tell the whole story.
Age can influence eye pressure, though there isn’t a single universal “normal by age” chart. Younger individuals often have eye pressure readings on the lower end of the normal spectrum. As people enter middle age, there can be a slight upward trend in average eye pressure levels. Seniors aged 70 and above may still fall within the 10-21 mmHg range, but their eye pressure is closely monitored due to increased susceptibility to certain eye conditions.
Why Eye Pressure Matters
Maintaining eye pressure within a healthy range is important for preventing damage to the optic nerve. High eye pressure, also known as ocular hypertension, occurs when the aqueous humor does not drain properly, causing fluid buildup. This elevated pressure can place stress on the optic nerve, which transmits visual information from the eye to the brain. Over time, sustained high pressure can damage the optic nerve, potentially leading to vision loss.
Conversely, low eye pressure, or hypotony, is less common but can also be problematic. When eye pressure is too low, the eye’s structural integrity can be compromised, similar to a deflated ball. This can lead to complications such as ciliochoroidal detachment, where fluid builds up abnormally, or hypotony maculopathy, which involves the collapse of the scleral wall and the development of macular folds. These structural changes can result in visual decline, including farsightedness and other vision distortions.
Factors Affecting Eye Pressure and When to Seek Professional Care
Beyond age, several factors can influence intraocular pressure. Genetics play a role, with a family history of glaucoma increasing an individual’s likelihood of developing the condition. Certain medications, particularly corticosteroids in eye drops or systemic forms, can increase IOP by reducing fluid outflow. Lifestyle choices also have an impact; for instance, rapid consumption of large volumes of water or heavy caffeine intake can cause transient elevations in IOP.
Underlying health conditions like diabetes, migraine, and high blood pressure can affect eye pressure and overall eye health. Thin corneas may lead to an underestimation of true IOP measurements, while thicker corneas can cause an overestimation. Regular comprehensive eye examinations are important, especially for individuals over 40 or those with risk factors like a family history of glaucoma. If you experience sudden symptoms such as severe eye pain, headaches, blurred vision, or seeing halos around lights, immediate medical attention is necessary.