Eye pressure can be too low, a condition medically termed ocular hypotony. While high eye pressure often receives more attention due to its connection with glaucoma, abnormally low pressure can also significantly affect vision and overall eye health. Maintaining stable eye pressure is important, as deviations can have implications.
Understanding Eye Pressure
Intraocular pressure (IOP) refers to the fluid pressure inside the eye. This pressure is maintained by the aqueous humor, a clear fluid that fills the front part of the eye, between the cornea and the iris. The aqueous humor provides nutrients to the eye’s structures and helps maintain the eye’s spherical shape, which is important for clear vision.
The eye continuously produces and drains aqueous humor to keep the pressure within a healthy range. A healthy range for IOP is between 10 and 21 millimeters of mercury (mmHg). Fluctuations within this range are normal, but consistent pressure below this level, particularly below 5 mmHg, indicates hypotony and can lead to complications.
Reasons for Low Eye Pressure
Low eye pressure can stem from various underlying causes, often related to an imbalance in the production and drainage of aqueous humor. A common reason is complications following ocular surgery, particularly glaucoma surgery like trabeculectomy. In these instances, the surgical drainage pathway may become overly efficient, leading to excessive fluid outflow.
Eye trauma, such as a penetrating injury, can cause fluid leakage from the eye, resulting in a sudden drop in pressure. Severe inflammation inside the eye, known as uveitis, can reduce the ciliary body’s ability to produce aqueous humor, contributing to hypotony. A retinal detachment, where the light-sensitive tissue at the back of the eye pulls away from its supporting layers, can also cause reduced eye pressure.
Certain medications, both systemic and topical, can lower IOP. Systemic medical conditions that affect the body’s overall fluid balance can also contribute to low eye pressure. Identifying the specific cause is important for effective management.
Impact of Low Eye Pressure
When eye pressure drops too low, it can lead to symptoms and serious consequences for vision. Vision disturbances are common, including blurry vision or reduced visual sharpness. The eye’s internal structures can be affected, leading to choroidal detachment, where the choroid layer separates from the sclera due to fluid accumulation.
A complication is hypotony maculopathy, involving swelling or damage to the macula, the part of the retina responsible for central, detailed vision. This condition can result in central vision loss. Optic disc swelling, known as papilledema, can also occur. Low pressure can also cause corneal edema, a swelling of the clear front surface of the eye. While hypotony is usually painless, severe cases can cause discomfort or pain in the eye.
Managing Low Eye Pressure
Diagnosing low eye pressure involves a comprehensive eye examination, including intraocular pressure measurement using a tonometer. Identifying the underlying cause of hypotony is an important step in guiding treatment. Treatment strategies depend on this underlying cause, aiming to restore a healthy pressure balance within the eye.
If inflammation is the cause, managing it with medications such as steroids is necessary. If previous eye surgery has resulted in excessive drainage, surgical intervention is required to repair leaks or modify the over-filtering bleb. Retinal detachment, when contributing to hypotony, is also treated through surgical repair. Discontinuing or adjusting medications that lower IOP can resolve the issue. For mild cases not causing significant symptoms, close observation by an ophthalmologist is sufficient. It is important to consult an eye care professional for proper diagnosis and a tailored management plan.