Strabismus (Crossed Eyes) and Amblyopia (Lazy Eye)
Understanding Strabismus and Amblyopia
Strabismus is a condition where the eyes do not point in the same direction at the same time. One eye may turn inward, outward, up, or down while the other eye looks straight ahead. This misalignment can be constant or may come and go at different times.
When the eyes are not working together, the brain receives two different images. Over time, the brain may learn to ignore the image from the misaligned eye, which can lead to vision problems if left untreated.
Amblyopia occurs when one eye has weaker vision than the other because the brain and that eye are not working well together. The brain begins to favor the stronger eye and ignores signals from the weaker eye. Amblyopia is primarily a problem of visual development in the brain, most often triggered by issues such as unequal focus, eye misalignment, or visual deprivation from conditions like cataract or a droopy eyelid.
Common types include strabismic amblyopia from eye misalignment, anisometropic amblyopia from unequal prescriptions, isoametropic amblyopia when both eyes are very out of focus, and deprivation amblyopia from blocked vision.
Without treatment, the weaker eye may never develop normal vision. Amblyopia is one of the most common causes of vision problems in children and can affect depth perception and overall visual function. In some children, both eyes can be affected.
Strabismus and amblyopia often occur together because the misalignment of the eyes can cause the brain to suppress the image from one eye. When this happens, the suppressed eye does not get the stimulation it needs to develop normal vision, leading to amblyopia. Up to half of children with strabismus develop some degree of amblyopia.
Treating the misalignment early can help prevent amblyopia from developing or worsening. Our eye doctor will evaluate both conditions and create a treatment plan that addresses your child's specific needs.
Eye misalignment can take several different forms depending on which direction the eye turns. Understanding the type of strabismus helps us determine the best treatment approach.
- Esotropia occurs when one or both eyes turn inward toward the nose
- Exotropia happens when one or both eyes turn outward away from the nose
- Hypertropia is when one eye turns upward higher than the other
- Hypotropia occurs when one eye turns downward lower than the other
- Intermittent versus constant eye turn
- Infantile esotropia versus accommodative esotropia
- Alternating versus unilateral strabismus
- Pattern strabismus such as A or V patterns
Recognizing the Signs and Symptoms
Babies and toddlers cannot tell you that they are having vision problems, so it is important to watch for visible signs of strabismus or amblyopia. You may notice that one eye seems to wander or does not move in sync with the other eye. Your child might tilt or turn their head to use only one eye or close one eye in bright sunlight.
Occasional crossing in the first 1 to 2 months of life can be normal. Constant eye crossing or an eye that consistently drifts after 3 months of age is not normal and should be evaluated.
Some infants appear crossed because of a wide nasal bridge or epicanthal folds, called pseudostrabismus. An exam can tell the difference.
- A white or off-center light reflex in one eye on photos
- An eye that seems always to turn in one direction
- Frequent squinting or closing one eye
Some children bump into objects on one side or have trouble judging distances when reaching for toys. Infants who consistently look at you with only one eye while the other drifts may need an eye exam, even if they seem too young.
School-age children with amblyopia or strabismus may complain of blurry vision, especially when reading or doing close work. They might have difficulty with activities that require depth perception, such as catching a ball or pouring liquids. Some children experience double vision or eye strain after reading.
Older children may feel self-conscious about the appearance of their eyes if the misalignment is noticeable to others. Academic performance can suffer if the child struggles to see the board or focus on printed materials.
Adults who had untreated childhood strabismus or amblyopia may have permanently reduced vision in one eye. Some adults develop strabismus for the first time due to injury, stroke, or other medical conditions affecting the eye muscles or nerves. Adult-onset strabismus typically causes double vision rather than amblyopia because the adult brain is less likely to suppress images the way a developing brain does.
Treatment options for adults may be more limited than for children, but improvement is still possible in many cases. We may recommend therapy to improve eye coordination or surgery to realign the eyes and reduce or eliminate double vision.
If you develop new double vision, avoid driving and hazardous activities until it is controlled with a patch or prism and evaluated by a clinician.
Certain symptoms suggest a more serious underlying condition that needs immediate evaluation. Sudden onset of eye misalignment or double vision in a child or adult should be examined right away, especially if it follows a head injury or occurs with headache, weakness, or confusion. Seek same-day urgent care or emergency evaluation for the following.
- Sudden eye turn that was not present before
- Double vision that starts abruptly
- Eye misalignment accompanied by severe headache or neurological symptoms
- Loss of vision in one or both eyes
- Eye turn that comes with pain or restricted eye movement
- White pupil in person or on flash photographs
- Fever, eyelid swelling, and painful or restricted eye movements
- New droopy eyelid with unequal pupils
- Bulging eye or new severe eye pain
- Constant eye crossing or drifting after 3 months of age
If in doubt, call us the same day or go to the emergency department.
Causes and Risk Factors
Children who have a parent or sibling with strabismus or amblyopia face a higher risk of developing these conditions themselves. Multiple genes appear to play a role in eye alignment and vision development. If you have a family history of these conditions, we recommend bringing your child in for an early comprehensive eye exam.
Some inherited syndromes and genetic conditions also increase the likelihood of eye misalignment. Knowing your family eye health history helps us watch for early signs and start treatment as soon as possible.
Significant differences in prescription between the two eyes, called anisometropia, can cause amblyopia because the brain favors the eye with clearer vision. Bilateral high refractive errors can cause amblyopia in both eyes. High levels of farsightedness in both eyes can lead to a type of strabismus called accommodative esotropia, where the eyes cross when trying to focus on near objects.
Uncorrected nearsightedness, farsightedness, or astigmatism in one or both eyes increases the risk of both conditions. Prescription eyeglasses can often correct these refractive errors and prevent or treat the misalignment and vision loss. Some children with a high AC/A ratio may benefit from bifocals to help keep the eyes straight at near.
Problems with the nerves that control eye movement or the muscles themselves can cause strabismus. Conditions like cerebral palsy, Down syndrome, and hydrocephalus are associated with higher rates of eye misalignment. Brain tumors, stroke, and traumatic brain injury can also disrupt the signals that keep the eyes working together.
We may work with your neurologist or other specialists to address underlying conditions that contribute to strabismus. Treating the neurological cause may improve eye alignment, though additional eye-specific treatment is often still needed.
Other causes include thyroid eye disease and myasthenia gravis in adults. Imaging or blood tests may be recommended when signs suggest a neurologic or systemic disorder.
Premature birth increases the risk of both strabismus and amblyopia, especially in babies who had retinopathy of prematurity or other complications. Conditions that affect one eye more than the other, such as cataracts, ptosis (drooping eyelid), or eye injuries, can prevent proper vision development and lead to amblyopia.
- Premature birth with low birth weight
- Congenital cataracts or other eye abnormalities present at birth
- Significant eye injuries during childhood
- Developmental delays or disabilities
Diagnosis and Testing
We begin with a review of your child's medical history and any symptoms or concerns you have noticed. Our eye doctor will observe how your child's eyes move and work together during different activities. For young children who cannot read an eye chart, we use special tests designed for their age and developmental level.
The exam is gentle and non-invasive. We make every effort to keep children comfortable and engaged throughout the process. Parents are welcome to stay in the exam room to help their child feel at ease. Dilating and cycloplegic eye drops are often used to relax focusing and allow accurate measurement of refractive error; near vision may be blurry and light sensitivity can last several hours.
We measure how well each eye sees by having your child identify letters, numbers, or pictures on a chart. For babies and toddlers, we use special techniques to assess whether each eye can fix on and follow a target. These measurements tell us whether amblyopia is present and how severe it may be.
Eye alignment tests show us exactly how the eyes are positioned and whether the misalignment is the same in all directions of gaze. We may cover one eye at a time and watch how the other eye moves to check for hidden misalignment that is not always visible. We perform a cycloplegic refraction to find the true glasses prescription in children.
Depth perception testing evaluates how well your child's brain combines images from both eyes to create three-dimensional vision. Poor depth perception often indicates that the eyes are not working together properly. We also assess how smoothly the eyes move when following a moving object and whether they can converge when looking at something close.
- Stereopsis tests measure the ability to perceive depth
- Cover-uncover tests reveal eye movement patterns and alignment
- Prism measurements quantify the degree of misalignment
- Refraction determines the need for corrective lenses
- Hirschberg and Krimsky tests for corneal light reflex alignment
- Worth 4 Dot or Bagolini testing for suppression and fusion
A full eye health exam, including the retina and optic nerve, is performed to look for conditions that can cause amblyopia.
After starting treatment, we will schedule regular follow-up appointments to monitor how your child is responding. These visits allow us to measure improvements in vision and alignment and make adjustments to the treatment plan if needed. Frequent monitoring is especially important during patching therapy to ensure the weaker eye is improving without the stronger eye losing vision.
Most children need follow-up visits every few weeks to months depending on their age and treatment type. Consistent monitoring helps us catch any problems early and keep treatment on track for the best possible outcome.
Do not start or change patching or penalization without guidance; over-occlusion can cause reverse amblyopia in the stronger eye.
Treatment Approaches
Eyeglasses are often the first step in treating both strabismus and amblyopia, especially when refractive errors are contributing to the problem. In some children, wearing the correct glasses prescription is enough to straighten the eyes and eliminate the misalignment. Glasses ensure that both eyes receive clear images, giving them an equal chance to develop properly.
Children with accommodative esotropia may find that their eyes stay straight when they wear their glasses but cross when the glasses are off. Consistent glasses wear is essential for these children to maintain proper alignment and prevent amblyopia. For children with a high AC/A ratio, bifocals may help keep the eyes straight at near.
Eye patching involves covering the stronger eye with an adhesive patch for a set number of hours each day. This forces the brain to use the weaker eye, which strengthens the vision in that eye over time. Patching works best when started early, but older children and even some adults can show improvement with consistent use.
The number of hours per day depends on how severe the amblyopia is and how your child responds to treatment. Many children improve with 2 hours per day for moderate amblyopia and about 6 hours per day for more severe cases; dosing is individualized and adjusted based on response. We will work with you to find a schedule that fits your family routine and helps your child succeed with treatment.
- Use an adhesive patch on the skin or an occlusive foil over glasses as directed
- Watch for skin irritation and call us if it occurs
- We monitor both eyes to avoid reverse amblyopia
Vision therapy consists of structured activities and exercises designed to improve how the eyes and brain work together. These exercises can enhance eye coordination, focusing ability, and depth perception. We may recommend vision therapy for children who continue to have problems with eye teaming and binocular vision even after other treatments.
- Eye tracking exercises to improve smooth eye movements
- Focusing activities that strengthen the eyes' ability to change focus quickly
- Stereopsis training to enhance depth perception
- Computer-based programs designed for visual skill development
Vision therapy is an adjunct for specific problems such as convergence insufficiency and some binocular vision issues. It does not straighten constant strabismus and does not replace patching or atropine for amblyopia.
When glasses, patching, and vision therapy do not fully correct the misalignment, we may recommend eye muscle surgery. During this procedure, the surgeon adjusts the position or tension of one or more of the muscles that control eye movement. The goal is to help the eyes work together and point in the same direction.
Surgery is typically done on an outpatient basis, and most children return to normal activities within a week or two. Some patients may need more than one surgery to achieve the best alignment. Eye muscle surgery can improve both the appearance and function of the eyes, though additional treatment like patching or therapy may still be needed afterward.
- Risks include overcorrection or undercorrection and the need for additional surgery
- Persistent or new double vision
- Infection, bleeding, scarring, and anesthesia risks
In adults, adjustable sutures may be used to fine-tune alignment after surgery. For infantile esotropia, earlier alignment can improve the chance of developing depth perception.
In certain situations, we may use specialized prism lenses in glasses to help align images and reduce double vision without surgery. Atropine eye drops placed in the stronger eye can blur its vision temporarily, which encourages use of the weaker eye similar to patching. This approach may be considered in specific cases for children who cannot tolerate a patch.
Botulinum toxin injections into one or more eye muscles can be used in selected cases to help reduce misalignment, either as a temporary measure or as part of a longer-term plan.
For adults with new-onset strabismus causing double vision, we sometimes recommend prisms or temporary patching of one eye while we investigate and treat the underlying cause. Treatment is individualized based on each patient's condition, age, and response to initial therapies. Typical regimens for atropine include daily or weekend dosing. Side effects can include light sensitivity and near blur.
After eye muscle surgery, your child's eyes may appear red and feel mildly sore for several days. We will prescribe eye drops or ointment to prevent infection and reduce discomfort. Most children can return to school within a few days but should avoid swimming and contact sports for a few weeks while the eyes heal. Temporary double vision can occur as the brain adapts. Avoid rubbing the eyes, swimming, and dusty environments until cleared.
Following patching or vision therapy, we continue to monitor your child's vision to ensure the improvements are maintained. Some children need to continue part-time patching or exercises for months or even years to prevent the amblyopia from returning. Consistent follow-up care and adherence to our recommendations give your child the best chance for lasting improvement.
Call us urgently for worsening pain, decreased vision, increasing redness or swelling, fever, or any concern for infection.
Frequently Asked Questions
Occasional crossing in the first 1 to 2 months can be normal. Constant crossing or drifting after 3 months should be evaluated.
Most children do not outgrow strabismus or amblyopia on their own, and waiting for spontaneous improvement often results in permanent vision loss. Early treatment offers the best chance for full recovery, so we encourage parents to seek an evaluation as soon as they notice any signs of eye misalignment or vision problems.
The brain is most responsive to amblyopia treatment during early childhood, making the preschool and early elementary years the ideal window for intervention. However, recent research shows that older children, teens, and even some adults can experience vision improvement with dedicated treatment, though progress may be slower and more limited than in younger patients.
Vision screening begins in infancy at well-child visits. A comprehensive eye exam is recommended earlier if there are concerns, and routinely by preschool age.
The timeline for improvement varies depending on the severity of the condition, the age of the patient, and the treatment method used. Some children show noticeable gains in vision within weeks of starting patching, while others may need several months of consistent treatment before we see significant progress. We reassess vision and alignment regularly and adjust the plan to maintain progress.
Yes, amblyopia can recur. We monitor after treatment and may prescribe part-time maintenance patching or drops to maintain gains.
Information here is educational and not a substitute for personalized medical advice. Seek urgent care for the red-flag symptoms listed.
Getting Help for Strabismus (Crossed Eyes) and Amblyopia (Lazy Eye)
If you notice any signs of eye misalignment or suspect your child may have vision problems, we encourage you to schedule a comprehensive eye exam. Early detection and treatment can prevent permanent vision loss and help your child develop clear, comfortable vision in both eyes.