Intraocular pressure (IOP) refers to the fluid pressure inside the eye, maintaining the eye’s shape and function. Internal pressure is regulated by continuous production and drainage of aqueous humor. A balanced flow ensures the eye remains properly inflated. While elevated eye pressure, often associated with glaucoma, receives considerable attention, low eye pressure can also lead to serious health concerns.
Normal intraocular pressure falls within a range of 10 to 21 millimeters of mercury (mmHg). Deviations from this range indicate underlying issues. Maintaining pressure within this healthy range is important for preserving vision and the structural integrity of the eye.
Recognizing the Signs
When eye pressure drops below the healthy range, individuals may notice several symptoms. Blurred vision is a common sign, as internal structures may not be properly supported. Eye pain or discomfort can also occur, often described as a dull ache or pressure behind the eye.
Redness may be present, signaling irritation or inflammation. Some report malaise or an unusual sensation within the affected eye. Symptoms can vary in intensity and appear gradually, so pay attention to any changes in vision or eye comfort.
Why Eye Pressure Drops
Low eye pressure, medically known as ocular hypotony, can stem from various underlying causes. Over-filtration following eye surgeries, especially those for glaucoma, is a common reason. The surgical drainage pathway may become too efficient, leading to excessive aqueous humor outflow.
Inflammation (uveitis) can also reduce aqueous humor production, lowering eye pressure. Eye trauma, like a penetrating injury, can disrupt fluid balance and lead to hypotony. Retinal detachment can also cause low eye pressure due to changes in fluid dynamics. Certain systemic medications or underlying medical conditions can also contribute.
Impact on Eye Health
Prolonged low eye pressure can have severe consequences for eye health and vision. The eye relies on adequate internal pressure to maintain its shape and align its delicate structures. When pressure is too low, the eye can lose its spherical form, leading to phthisis bulbi, where it shrinks and becomes non-functional.
A serious complication is choroidal detachment, where the choroid (a vascular layer supplying blood to the retina) separates from the sclera. This separation can compromise the eye’s blood supply and disrupt its function. Maculopathy, damage to the macula (the central part of the retina responsible for sharp vision), can also develop, leading to central vision loss. Without intervention, chronically low eye pressure can result in irreversible damage to the retina and optic nerve, causing permanent vision impairment or blindness.
Diagnosis and Management
Diagnosing low eye pressure involves a comprehensive eye examination. Tonometry, a test measuring intraocular pressure directly, is a key component. This measurement, often performed with specialized instruments, determines if pressure is below the normal range (below 5 mmHg). Additional tests, such as optical coherence tomography (OCT) or ultrasound, may assess the eye’s structural integrity and identify complications like choroidal detachment or maculopathy.
Management depends on identifying and addressing the underlying cause. Treatment varies, from careful observation for mild cases to medications that increase aqueous humor production or reduce outflow. Surgical interventions may be necessary to repair leaks, address over-filtering blebs from previous surgeries, or reattach a detached retina. Consulting an eye care professional is important for accurate diagnosis and a personalized treatment plan to prevent long-term complications and preserve vision.