Hypotropia

What is hypotropia?

Hypotropia is a form of eye misalignment (strabismus) in which your eye turns downward involuntarily. It’s the opposite of hypertropia (an upward eye turn). You may have hypotropia by itself, or your eye may drift downward and to one side. Hypotropia with esotropia (an inward turn) often occurs with a condition called heavy eye syndrome. Hypotropia can also occur with exotropia (an outward turn).

Types of hypotropia

Hypotropia can be:

• Congenital or acquired. It’s often related to a disorder that you’re born with, and it’s commonly diagnosed in childhood. But it can also occur later in life due to a new condition.
• Unilateral or bilateral. It usually affects one eye at a time, and usually the same eye. But in some cases, it affects different eyes at different times or, very rarely, both eyes at once.
• Constant or intermittent. Your eye may turn downward all the time, or only sometimes. With dissociated hypotropia, your eye drifts when your brain isn’t paying attention to it.

When you have hypotropia, you can’t control your wayward eye movements, and you may not even realize they’re happening. Children with this condition may be too young to understand how their eyes are different. This can be both socially and physically awkward. Whether you’re a child or the parent of that child, or even an adult developing hypotropia, it can bring a variety of challenges — not all of them visual.

What are hypotropia symptoms?

When your eyes won’t coordinate, it can cause binocular vision dysfunction, with symptoms including:

• Blurry vision
• Double vision
• Eye strain
• Headaches
• Impaired depth perception

Some people develop a head tilt in the effort to see better, which can cause neck stiffness and pain. Head tilts in children can affect how they grow. For example, they may develop asymmetrical faces.

Is hypotropia serious?

Hypotropia might affect you a little or a lot, depending on how often it happens and how severe it is. You might have difficulty or discomfort with tasks that require close vision, like reading or sewing. Eye misalignment in children can worsen over time. In some cases, it can lead to amblyopia (lazy eye). This is more likely if the child is younger, which is why regular screenings from an early age are so important.

What causes hypotropia?

Hypotropia happens when something prevents the muscles around your eye from moving it up and down normally. Disorders or injuries that affect these muscles may weaken, pull or trap them. Sometimes the nerves that activate these muscles are unable to do so. Disorders or injuries that affect your nervous system can damage these nerve pathways. There are many possible causes, including:

• Brain lesions
• Brown syndrome
• Extraocular muscle fibrosis
• Moebius syndrome
• Neuromuscular disorders
• Oculomotor nerve palsy
• Orbital fractures
• Thyroid eye disease
• Trochlear nerve palsy
• Tumors

How do healthcare providers diagnose eye misalignment?

Eye care specialists diagnose hypotropia with a thorough eye exam and specialized tests. These tests help them determine the degree of eye misalignment you have and how it’s affecting your vision.

Tests may include:

• Bruckner test. Your provider will shine a light and observe its reflection from your retinas.
• Hirschberg test. Your provider will shine a smaller light and observe its reflection on your corneas.
• Krimsky test. Your provider will place prisms in front of your eye during the Hirschberg test.
• Cover/uncover test. Your provider will briefly cover one eye and watch the other one adjust.
• Prism cover test. Your provider will place prisms in front of your eye during the cover test.
• 4 dot test. You’ll look for colored dots, wearing different colored filters over your eyes.
• Red filter test. This test involves looking at a light with a red-colored filter over one eye.
• Maddox rod test. You’ll look through one lens that distorts light into a line instead of a point.
• Double Maddox rod test. The lenses will be placed over both eyes and you’ll compare the lines.
• Bagolini striated lens test. You’ll look at a light through striated lenses that produce two lines.
• Titmus/randot test. Wearing polarized glasses, you’ll look at a book with 3-D images.

You may need other tests, or to see another healthcare provider, to diagnose the underlying cause of your misalignment. This is important because the cause will determine the best treatment approach.

What is the treatment for hypotropia?

The treatment depends on the cause. In some cases, treating the cause will correct hypotropia. In other cases, it won’t. You might need to wear prescription lenses and prisms to correct your vision.

Can you fix hypotropia?

Depending on the cause, nonsurgical treatments can sometimes fix hypotropia. Your provider will try these options first. If they don’t work, they might recommend surgery to fix it. Strabismus surgery adjusts the muscles around your eye to correct the misalignment. It corrects the appearance of hypotropia and will often correct your vision. But some people may still need corrective lenses and prisms.

What is the prognosis?

With early diagnosis and treatment, the prognosis (outlook) is good. Hypotropia that goes untreated too long may be harder to treat later. In children, untreated hypotropia can lead to loss of depth perception or amblyopia (lazy eye) and permanent vision loss in the affected eye. It’s daunting to send a young child into eye surgery. But children who have surgery when it’s recommended have excellent outcomes.