Hypertropia is a condition where one eye points upward. It is one of four types of eye misalignment, or “strabismus.” The condition can cause depth perception issues and blurred vision.

Strabismus most commonly develops in infants and young children but can also develop in adults. Early and effective treatment can help improve visual focus and prevent long-term vision complications.

This article discusses hypertropia, including its symptoms, causes, and treatments.

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Hypertropia, or vertical strabismus, is a condition in which the eyes misalign. For example, one eye may point upward.

According to the American Optometric Association (AOA), there are four types of strabismus. These are:

  • hypertropia, where one eye points upward
  • hypotropia, where one eye points downward
  • esotropia, where one eye points inward toward the nose
  • exotropia, where one eye points outward toward the ear

Strabismus most commonly develops in infants and young children but can also develop in adulthood.

Effect on vision

Each eye is attached to six muscles that control eye movement.

With typical vision, the six muscles in each eye work together to focus both eyes on the same image. The brain then combines the image from each eye into a single, three-dimensional image.

This process enables depth perception, which is the ability to determine how near or far an object is.

The American Association for Pediatric Ophthalmology and Strabismus (AAPOS) explains that hypertropia involves each eye sending a different signal to the brain.

In young children, the brain learns to ignore the image from the misaligned eye. However, this can cause issues such as:

  • a “lazy eye,” which doctors call amblyopia
  • inaccurate depth perception
  • vision development issues in the affected eye

The main sign of hypertropia is an eye that points upward.

According to the American Optometric Association (AOA), some individuals with strabismus have persistent strabismus, while others experience only intermittent strabismus.

Intermittent strabismus can occur due to the following:

According to the AOA, strabismus most commonly develops in infants and children below the age of 3 years.

Children with strabismus may close one eye or tilt their heads when looking at objects to try to improve their focus.

According to the AOA, strabismus may result in the following symptoms:

  • frequent blinking or squinting, particularly in bright sunlight
  • depth perception issues
  • double vision
  • amblyopia
  • vision issues in the misaligned eye

Two cranial nerves — cranial nerve 3, known as the oculomotor nerve, and cranial nerve 4, known as the trochlear nerve — control the muscles that move the eyes vertically.

Anything that damages these nerves, the muscles, or the brain can cause hypertropia, including:

  • stroke
  • eye injuries
  • damage during or after eye surgery

Certain health conditions can also cause hypertropia, including:

An eye doctor, known as an ophthalmologist, will conduct a comprehensive eye examination to determine whether an individual has hypertropia.

The examination may include the following:

  • A medical history assessment: This includes an assessment of the person’s symptoms and any underlying health issues they have or any medications they are taking.
  • A visual acuity test: This test helps determine how much the strabismus affects the person’s vision. The test involves reading letters on a reading chart from different distances.
  • A refraction test: This test helps determine the lens power necessary to compensate for refractive issues, such as nearsightedness, farsightedness, or astigmatism. It involves placing a series of lenses in front of the eye and using a tool called a retinoscope to measure how effectively each lens focuses light.
  • Tests of alignment and focusing: These tests help detect problems that prevent the eyes from focusing effectively or make it difficult for both eyes to work together.
  • An eye health examination: This examination involves an assessment of the internal and external structures of the eyes under typical seeing conditions. It helps the ophthalmologist rule out any underlying eye disease that may contribute to strabismus.

According to the AAPOS, the goal of strabismus treatment is to improve eye alignment so that a person can achieve better vision. Treatments include the following:

  • Prism lenses: These lenses are thicker on one side, causing them to alter light as it enters the eye. This reduces the amount of turning necessary for the eye to focus on objects, sometimes eliminating the need for the eye to turn at all.
  • Eye muscle surgery (EMS): Surgery can alter the length or position of the muscles around the eyes so that both eyes have correct alignment. Most people who undergo EMS will require vision therapy to help prevent the eyes from becoming misaligned again in the future.

According to the AOA, detecting and treating strabismus in its early stages can often correct the issue.

The United Kingdom’s Royal National Institute of Blind People explains that children who receive strabismus treatment after the age of 8 years are less likely to have successful results.

However, most adapt well to reduced vision in one eye and will not experience any everyday problems.

Those with no vision issues in one eye should receive regular eye examinations to ensure the eye remains healthy.

Hypertropia is a type of eye misalignment, known as strabismus, in which one eye points upward. The condition can cause depth perception issues, blurred vision, and a lazy eye.

Early and effective strabismus treatment can help prevent long-term vision problems in the affected eye. It can also lead to a complete resolution of strabismus in some cases.

Anyone with concerns about strabismus in themselves or a child can talk with a doctor for further advice and guidance.

A specialist eye doctor or ophthalmologist can conduct tests to identify strabismus and recommend appropriate treatments, such as eyeglasses, prism lenses, or vision therapy.