Hypotony (also called ocular hypotony) is a condition where the pressure inside the eye (intraocular pressure or IOP) is abnormally low and is causing changes to the structure or function of the eye.
The eye normally maintains a healthy pressure through a balance between the production and drainage of fluid inside the eye. When the pressure becomes too low, the eye can lose its normal shape and support. This can affect important structures such as the retina, choroid and cornea, leading to blurred vision, visual distortion and, in some cases, permanent sight loss.
Hypotony cannot usually be diagnosed from a pressure reading alone. Many people have pressures that are lower than average without any problems. Instead, ophthalmologists diagnose hypotony based on a combination of findings, including:
Low intraocular pressure.
Changes in the structure of the eye.
Changes seen on examination or imaging.
Visual symptoms or reduction in vision.
Some people with low eye pressure experience very few symptoms, while others develop significant visual problems requiring specialist treatment.
Key points
Hypotony is a condition where low eye pressure causes changes to the structure or function of the eye.
Not all patients with low eye pressure have hypotony or require treatment.
Treatment is focused on preserving vision, restoring the structure of the eye and maintaining long-term eye health.
Moorfields Eye Hospital has a dedicated specialist service for acute and chronic hypotony.
Assessment may include advanced retinal imaging, specialist ultrasound examination of the ciliary body and electrodiagnostic testing.
Treatment often requires multiple visits over several weeks or months and should be viewed as a gradual process rather than a quick fix.
A range of medical, surgical and viscoelastic treatments may be used depending on the underlying cause and the visual potential of the eye.
Moorfields Eye Hospital is one of the few centres internationally with a dedicated service for acute and chronic hypotony.
Our multidisciplinary team includes specialists in retinal disease, uveitis, glaucoma and ocular trauma, working together to diagnose the cause of low eye pressure and develop an individualised treatment plan.
Patients benefit from:
• Specialist expertise in complex hypotony.
• Comprehensive assessment of the underlying cause.
• Advanced retinal imaging and OCT scanning.
• Specialist ultrasound assessment of the ciliary body.
• Electrodiagnostic testing to assess retinal function and visual potential where appropriate.
• Access to innovative viscoelastic treatments.
• Multidisciplinary management involving retinal, uveitis and glaucoma specialists.
• NHS and private treatment pathways.
Our dedicated service combines advanced diagnostics with specialist treatment options to help preserve vision, maintain the structure of the eye and improve quality of life.
Treatment depends on the cause of the hypotony, how long it has been present and whether there is potential for visual improvement.
Observation
Some patients with mild hypotony and stable vision may be monitored carefully without immediate intervention.
Medical treatment
Treating underlying inflammation, such as uveitis, may allow eye pressure to recover naturally. Other medications may be used depending on the cause.
Surgical treatment
If hypotony is caused by a wound leak, excessive fluid drainage or another structural abnormality, surgery may be required to correct the underlying problem.
In some patients, traction between the vitreous gel and the retina may contribute to persistent hypotony. In these situations, we are often more likely to recommend early vitreoretinal surgery, as relieving traction can play an important role in restoring the normal structure and function of the eye.
Similarly, if there is another surgical problem that is driving the hypotony, this will usually be addressed first. Examples include:
Retinal detachment requiring retinal surgery.
Persistent retinal traction or scarring.
An over-draining glaucoma operation that requires revision.
Surgical wound leaks or other causes of excessive fluid loss from the eye.
Addressing the underlying cause provides the best chance of achieving a stable long-term outcome. Once this has been treated, additional measures such as viscoelastic treatment or silicone oil may be considered where appropriate.
Silicone oil
Silicone oil remains an important treatment option for some patients with chronic hypotony. It can help maintain the shape and structural integrity of the eye when long-standing low pressure has caused the eye to soften or shrink.
In addition to providing internal support, silicone oil may be beneficial in certain patients with reduced vision because it can provide a degree of optical magnification, which may improve functional vision. The amount of visual benefit varies depending on the underlying condition and the anatomy of the eye.
Silicone oil does not restore the eye's ability to produce fluid and is not suitable for every patient. Long-term use can also be associated with complications, including reduced visual clarity, cataract formation, glaucoma and corneal problems.
The Moorfields hypotony team will discuss whether silicone oil, viscoelastic treatment or an alternative treatment approach is most appropriate for your individual circumstances.
Intravitreal viscoelastic treatment
Moorfields Eye Hospital has pioneered the use of intravitreal viscoelastic treatments for selected patients with chronic structural hypotony.
Viscoelastics are gel-like materials that have been used safely in ophthalmic surgery for many years. When carefully injected into the vitreous cavity, they can help support the retina and other internal structures of the eye, allowing the eye to regain a more normal shape and function.
Our research has shown that in selected patients, viscoelastic treatment can improve eye pressure, restore the anatomy of the eye and improve vision. The aim of treatment is not simply to increase the pressure reading, but to restore structural support and stability to the eye.
It is important to understand that treatment is usually a gradual process rather than a quick fix. Many patients require a series of injections over several months and may need to attend clinic every 1–2 weeks during the initial phase of treatment. The aim is to gradually restore and maintain the normal structure of the eye until it becomes stable.
Different viscoelastic materials may be used depending on the individual circumstances of the patient. Your specialist will discuss the most appropriate treatment approach for you.
Treatment is available through the dedicated Moorfields hypotony service for suitable patients, both privately and through the NHS.
Acute hypotony
Acute hypotony develops suddenly, often following eye surgery, eye injury or severe inflammation inside the eye. It may resolve once the underlying cause is treated.
Chronic hypotony
Chronic hypotony is long-standing low eye pressure that persists over time. It is often associated with reduced fluid production within the eye and can lead to progressive structural changes, visual loss and, in severe cases, shrinkage of the eye.
Numerical hypotony
Sometimes the eye pressure measures below the normal range, but the eye remains structurally healthy and vision is unaffected. This is known as numerical hypotony.
In these cases, the pressure itself may not be causing any harm. Some people naturally have lower eye pressures than others, and in some patients low pressure may be an intended outcome following glaucoma surgery or treatment with pressure-lowering eye drops.
Patients with numerical hypotony do not necessarily require treatment. Instead, the focus is on monitoring the eye to ensure that vision and the structure of the eye remain stable over time.
Hypotony is relatively uncommon but can affect adults of any age.
People may be at increased risk if they:
Have had previous eye surgery, particularly glaucoma surgery.
Have chronic inflammatory eye conditions such as uveitis.
Have experienced significant eye trauma or injury.
Have certain retinal conditions, including retinal detachment.
Have underlying eye diseases that affect the ciliary body, the part of the eye responsible for producing the fluid that maintains normal eye pressure.
Hypotony occurs when there is either:
Too little fluid being produced inside the eye.
Too much fluid draining or leaking out of the eye.
Common causes include:
Inflammation inside the eye (for example, uveitis).
Previous eye surgery, including glaucoma or cataract surgery.
Eye injury or trauma.
Retinal detachment and other retinal disorders.
Conditions that damage the ciliary body, the part of the eye that produces fluid within the eye.
Symptoms vary from person to person and depend on how low the eye pressure is and how long it has been present.
Symptoms may include:
Blurred or reduced vision.
Distorted vision.
Eye discomfort or aching.
Increased sensitivity to light.
Floaters or flashes of light, depending on the underlying cause.
A gradual decline in sight over time.
Some patients may have low eye pressure without obvious symptoms, particularly in the early stages.
Find out more about treatment options for Hypotony
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