Hypotropia is when one eye tilts downward. It’s often caused by problems with the muscles around your eyes or the nerves that control them.

Hypotropia falls into a group of conditions called strabismus, all of which involve a misaligned eye. Strabismus is thought to affect 2–5% of the population.

Six extraocular muscles wrap around your eyeball and allow you to lift your eyelid and shift your gaze. Strabismus can develop if these muscles or the nerves that control them don’t work properly.

Conditions that restrict your eye, such as tumors or irregularities in eye shape, can also lead to misalignment.

Hypotropia is often present from childhood, but it can develop in adults.

In this article, we examine hypotropia in more depth, including potential causes and treatment options.

Hypotropia, or downward ocular deviation, occurs when one of your eyes tilts downward when both eyes are open. It may be constant or come and go.

Hypotropia falls into a group of conditions called strabismus, which involve misalignment of an eye. More specifically, it’s categorized as a vertical strabismus, meaning your eye is misaligned vertically.

Hypotropia can range from mild to severe. The degree of misalignment is measured in units called prism diopters.

What is a sunset sign?

The sunset sign, which is often seen in infants up to 7 months of age, involves hypotropia in both eyes due to the immaturity of their reflexes. It often resolves without needing treatment.

The sunset sign can also indicate hydrocephalus, a medical emergency caused by the buildup of fluid inside the skull and brain. In babies, hydrocephalus can cause the head to swell many times its typical size. The sunset sign occurs in as many as 40% of children with hydrocephalus.

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Strabismus is often caused by problems with the muscles or nerves that control your eye. It can also be caused by conditions that restrict your eye or irregularities in the shape of your eyeball.

Potential underlying causes include:

Additionally, Brown syndrome usually causes hypotropia on one side and occasionally on both sides. Brown syndrome is usually present from birth. It’s caused by an abnormality in the superior oblique muscle.

Strabismus risk factors

Some groups of people have an especially high risk of developing strabismus. Risk factors include:

Hypotropia and hypertropia both cause vertical misalignment of your eye. In hypertropia, one eye tilts upward, whereas in hypotropia it tilts downward. The prefix “hypo” comes from Greek and means “below” or “under.” The prefix “hyper” means “above” or “high.”

The terms “esotropia” and “exotropia” refer to horizontal misalignment of an eye. Esotropia involves an inward tilt of an eye, while exotropia involves an outward tilt.

Strabismus often occurs in childhood. But some potential causes of strabismus, such as thyroid eye disease and trauma to your eye, can develop in adulthood.

An eye doctor will perform an eye exam to find the underlying cause of hypotropia. Some potential underlying conditions, such as tumors, are serious and may need surgical treatment.

It’s important to consult your eye doctor before starting any type of exercise program to try to treat hypotropia.

If the underlying cause is a problem with one of the muscles around your eye, your doctor may recommend that you perform orthoptic exercises to try to fix the problem. Orthoptic exercises are designed to improve the control of your eye muscles.

One example is the pencil push-up for treating exotropia. This treatment involves holding a pencil at arm’s length and slowly moving it toward your nose.

Learn more about eye exercises for strabismus.

The treatment for hypotropia depends on the underlying cause. Prompt evaluation and treatment are needed to avoid potential vision damage. The primary goal of treatment is to restore proper eye alignment. The secondary aim is to correct changes to your vision.

Potential treatment options for a misaligned eye include:

  • Observation alone: No treatment may be necessary if the underlying condition is treatable. Conditions that may improve with time include:
    • myasthenia gravis
    • diabetic neuropathy
    • traumatic causes
  • Correction of vision issues: Prescription glasses can correct the way light reflects through your eye, potentially addressing vision problems.
  • Correcting eye weakness: Patching of the better eye is the gold standard for treating reduced visual acuity in people with misalignment. Patching is usually recommended for 2–6 hours per day and works best in children less than 7 years old.
  • Orthoptics: Orthoptics are exercises used to strengthen the muscles around your eyeball. They may help if muscle weakness is the underlying cause.
  • Botulinum toxin: Injections of botulinum toxin may help treat misalignment by temporarily paralyzing muscles around your eye.
  • Extraocular muscle surgery: If all other treatments fail, surgery may be necessary to correct problems with the muscles around your eye. Surgery may aim to:
    • strengthen a muscle
    • weaken a muscle
    • change the angle at which a muscle pulls on your eye

Hypotropia is a misalignment of one of your eyes that causes it to tilt downward. It often occurs in young children due to problems with the muscles that surround the eye or the nerves that control these muscles. It can also develop in adults due to factors such as thyroid eye disease and trauma to the eye.

It’s important to see an eye doctor if you notice that you or your child has eye misalignment. Some of the potential causes are serious and may need prompt medical attention.