Intraocular pressure (IOP) refers to the fluid pressure within the eye. This internal pressure maintains the eye’s shape and ensures its proper function. High eye pressure often causes no noticeable symptoms. Maintaining a healthy IOP range is important for preserving overall eye health and vision.
How Eye Pressure is Regulated
The eye continuously produces a clear fluid called aqueous humor, which fills the front portion of the eye and helps maintain pressure. This fluid is generated by the ciliary body, a structure located behind the iris. Aqueous humor provides nourishment to the lens and cornea, which lack their own blood supply.
After its production, the aqueous humor flows through the pupil into the anterior chamber of the eye. From there, it drains out through a specialized mesh-like tissue known as the trabecular meshwork. This meshwork acts as a filter, allowing the fluid to pass into Schlemm’s canal, a drainage channel that ultimately connects to the bloodstream. A constant balance between the production and drainage of aqueous humor keeps the eye pressure stable. If this delicate equilibrium is disrupted, fluid can accumulate, leading to an increase in intraocular pressure.
Factors Leading to Increased Eye Pressure
Elevated eye pressure often results from an imbalance where aqueous humor does not drain efficiently from the eye. The primary mechanism involves blockages or impairment within the trabecular meshwork. Debris, pigment, or cellular material can obstruct this meshwork, hindering fluid outflow.
Less commonly, excessive aqueous humor production by the ciliary body can contribute to increased pressure. Certain external and internal factors can also disrupt fluid dynamics within the eye. Medications, particularly corticosteroids (oral, inhaled, or topical), are known to elevate intraocular pressure.
Eye trauma can directly damage drainage structures, leading to long-term pressure changes. Inflammation within the eye, known as uveitis, can cause swelling and cellular debris that physically block drainage pathways. Certain anatomical variations, such as a narrow drainage angle, can restrict the space where fluid exits the eye, causing pressure to build.
Other specific eye conditions can also lead to increased pressure. Pseudoexfoliation syndrome involves the buildup of microscopic protein fibers that can clog the trabecular meshwork. Pigment dispersion syndrome occurs when pigment rubs off the iris and accumulates in the drainage system, impeding fluid outflow.
Conditions Associated with Elevated Eye Pressure
Ocular hypertension is diagnosed when intraocular pressure is higher than the normal range (above 21 mmHg), without detectable damage to the optic nerve or vision loss. Individuals with ocular hypertension are closely monitored due to the risk of developing glaucoma.
Glaucoma encompasses a group of eye diseases characterized by damage to the optic nerve, which transmits visual information to the brain. This damage is frequently, not always, linked to elevated intraocular pressure. High pressure can harm the fibers of the optic nerve, potentially leading to irreversible vision loss.
Primary Open-Angle Glaucoma is the most common type, progressing slowly with the eye’s drainage angle appearing open, yet fluid outflow is inadequate. Angle-Closure Glaucoma can occur suddenly and be painful, or it may develop chronically, where the iris blocks the drainage angle. Secondary Glaucoma arises from other underlying conditions, such as eye injuries, inflammation, or certain medications, that cause the pressure to increase.
When to Seek Medical Attention and What to Expect
Since high eye pressure often produces no noticeable symptoms, routine eye examinations are important for early detection. However, certain acute symptoms warrant immediate medical attention, including sudden eye pain, redness, blurred vision, or seeing rainbow-colored halos around lights. These symptoms can indicate a rapid and severe increase in eye pressure.
During an eye exam, intraocular pressure is measured using tonometry. This can involve an instrument that gently touches the eye after numbing drops are applied, or a non-contact method using a puff of air. If high pressure is detected, management aims to reduce it and preserve vision. Treatment options include prescription eye drops to either decrease fluid production or improve drainage. In some cases, laser procedures or surgery may be considered to facilitate fluid outflow.