An eye pressure reading of 40 millimeters of mercury (mmHg) is an extremely high measurement that constitutes a medical emergency. This reading is not within a normal range and presents a significant and immediate risk to vision. It requires urgent medical attention to prevent irreversible damage.
What High Eye Pressure Means
Intraocular pressure (IOP) refers to the fluid pressure inside the eye. This pressure is maintained by a continuous production and drainage of a clear fluid called aqueous humor. Normal eye pressure falls within a range of 10 to 21 mmHg.
A reading of 40 mmHg indicates a severe elevation. This signifies a substantial imbalance in the eye’s fluid dynamics, where the fluid is either overproduced or not draining efficiently. Sustained high pressure can exert undue force on the delicate structures within the eye.
The Immediate Threat of Elevated Eye Pressure
An eye pressure of 40 mmHg poses an immediate threat primarily due to its potential to damage the optic nerve. The optic nerve transmits visual information from the eye to the brain, and sustained high pressure can compress and injure its delicate fibers. This damage can result in irreversible vision loss, beginning with peripheral (side) vision and potentially progressing to central vision if left unaddressed.
Such a sudden and severe elevation in eye pressure is associated with acute angle-closure glaucoma, a condition requiring emergency intervention. In this condition, the eye’s drainage angle, where the aqueous humor normally exits, becomes suddenly blocked. This blockage leads to a rapid buildup of fluid and pressure within the eye.
Symptoms accompanying this acute pressure spike include severe eye pain, headache, blurred or hazy vision, seeing rainbow-colored halos around lights, nausea, and vomiting. The rapid onset of these symptoms, combined with high eye pressure, indicates an urgent situation where vision can be lost quickly.
Urgent Medical Steps and Diagnosis
When eye pressure reaches 40 mmHg, emergency medical attention is required without delay. This involves going to an emergency room or an urgent eye care clinic. Prompt evaluation by an ophthalmologist assesses the situation and initiates appropriate treatment.
During the examination, an ophthalmologist will perform several diagnostic tests. Tonometry is used to measure the intraocular pressure, which involves gently touching a device to the surface of the numbed eye. This provides an accurate reading of the eye’s internal pressure.
Further tests determine the cause and extent of any damage. A slit-lamp exam microscopically examines the front and internal structures of the eye, including the cornea, iris, and lens. Gonioscopy evaluates the eye’s drainage angle, determining if it is open or closed, which helps identify angle-closure glaucoma. A visual field test assesses peripheral vision to detect blind spots or vision loss caused by optic nerve damage.
Ongoing Care and Vision Preservation
Once the immediate crisis of high eye pressure is managed, ongoing treatment prevents future damage and preserves vision. This long-term management involves a combination of approaches tailored to the individual’s condition, requiring regular follow-up appointments and adherence to the prescribed treatment plan for monitoring eye pressure, assessing optic nerve health, and preserving vision over time.
Treatment includes eye drops that reduce fluid production or improve fluid drainage from the eye. Oral medications, such as carbonic anhydrase inhibitors, may also be prescribed for very high pressures or when eye drops are insufficient.
Laser procedures are another treatment. Selective laser trabeculoplasty (SLT) improves fluid outflow by targeting the eye’s drainage system. Laser peripheral iridotomy (LPI) creates a small opening in the iris for fluid drainage, particularly in angle-closure glaucoma. Surgical options like trabeculectomy or drainage device implantation may be considered if other treatments do not adequately control pressure.