What is BVD (Binocular Vision Dysfunction)?

Overview

What is BVD?

Have you ever wondered why, despite having two eyes, you see only one seamless image? This is called binocular vision. Our brain is so intricate and complex that it’s able to turn what two separate eyes see into one clear image.

For this to occur, the eyes need to be in perfect alignment. In people who have good binocular vision, their eyes work in tandem and are perfectly synced at all times. This allows their brain to create one clear, focused image.

But what happens when the eyes don’t work together? If eyes are not perfectly synchronized, this is called Binocular Vision Dysfunction. For people who have BVD, their eyes are not in alignment (not in sync), so their eyes will transmit two images to the brain that are in slightly different positions from one another.

The brain has difficulty creating one clear image from two out-of-sync images. It responds by forcing the eye-aligning muscles to realign the eyes. The realignment is only temporary. Misalignment then recurs, which is followed again by realignment. This misalignment-realignment cycle is the cause of the symptoms of BVD.

How Your Eyes Work: The 3 Components of Binocular Vision

For a better grasp on what BVD is, it’s helpful to understand how binocular vision works. Binocular vision depends on three key components: seeing clearly, blending the images, and judging depth.

• Seeing Clearly (Macular Perception): This is the brain’s ability to recognize images from both eyes via the macula (the part of the retina responsible for sharp vision). At this stage, the brain processes the inputs but doesn’t merge the images.
• Blending Images (Fusion): Fusion involves the brain merging images from both eyes into one. Problems with this process are described in research on abnormal visual processing in binocular fusion disorders. It includes:
  • Motor Fusion: Physical eye alignment to ensure both eyes are aimed at the same point.
  • Sensory Fusion: The brain’s merging of the two aligned images. Problems with sensory fusion can lead to visual discomfort.
• Judging Depth (Stereopsis): This is the brain’s ability to perceive depth by processing the slight differences between images from each eye. It’s essential for tasks requiring depth perception, like driving or catching a ball.

When macular perception, fusion, and stereopsis work together, the brain turns two separate images into one clear view of the world. But even a small misalignment can lead to BVD symptoms.

NeuroVisual Medicine’s Dr. Rosner Explains Binocular Vision Dysfunction

Learn as Dr. Mark Rosner gives an in-depth explanation of the different symptoms an individual suffering from BVD can experience, from moderate to severe.

Mark Rosner, MD, is a physician and clinical researcher. He is passionate about bringing Binocular Vision Dysfunction (BVD) into broader medical awareness. With two decades of studying why so many people experience headaches, dizziness, anxiety, and visual discomfort that traditional testing can’t explain, Dr. Mark shows that even tiny visual misalignments can cause major symptoms.

“BVD is more common than most people realize. Many of our patients saw specialist after specialist, trying to find relief for symptoms that were actually caused by visual misalignment. Once we were able to properly diagnose them and provide treatment, their symptoms markedly improved.”

–Mark Rosner, MD

Causes of Binocular Vision Dysfunction

Binocular Vision Dysfunction is often mistaken for sinus issues or migraines. But it can result from a variety of sources, ranging from how the eyes and brain develop early in life to injuries or conditions that affect them later on.

Binocular Vision Dysfunction can occur at any age. Symptoms in children usually stem from congenital or developmental causes. Congenital or developmental conditions can occur at any age, but most commonly around age 40. Or symptoms may appear after suffering a concussion or brain injury.

Understanding what’s behind BVD is the first step to finding the right treatment.

Congenital and Developmental Causes

Facial Asymmetry

People with Binocular Vision Dysfunction often have facial asymmetry, where one eye is physically higher than the other eye, and they tilt their heads to improve vision and reduce symptoms. This head tilt can help, but may lead to neck pain and headaches.

Eye Muscle Problems

Weak or paralyzed eye muscles can lead to misalignment and BVD. Eye muscle problems can be caused by conditions like cranial nerve palsies or injuries, thyroid eye disease, ALS, or myasthenia gravis.

Refractive Errors

Uncorrected refractive errors, like astigmatism, can cause discomfort and blurred images that are difficult to fuse. This pattern has been documented in research on accommodative and binocular vision dysfunctions. When prescriptions differ between eyes (anisometropia), it becomes difficult to merge images, causing blurred vision.

Genetic Factors

Genetic predispositions can affect the eyes and visual system. This may lead to BVD due to developmental or functional issues.

Developmental Issues

Childhood conditions like amblyopia (lazy eye) can cause BVD if untreated, as the weaker eye doesn’t develop proper visual function.

Additional Causes and Related Conditions

Strabismus

Known as wandering eyes, strabismus (crossed eyes) occurs when the eyes don’t align properly. This disrupts eye coordination and may lead to issues with fusion, stereopsis, and binocular depth perception.

Convergence Insufficiency

Convergence insufficiency occurs when the eyes struggle to work together for close-up tasks, leading to headaches, eye strain, and vertigo. This can make reading difficult due to poor motor fusion.

Neurological Disorders

Neurological conditions like multiple sclerosis (MS), stroke, concussions, or traumatic brain injuries can damage nerves controlling eye movements, leading to BVD.

Injuries

Trauma to the head or eyes can damage muscles, nerves, or structures, causing difficulties in maintaining proper binocular vision.

Whether BVD develops early in life or later due to injury or illness, BVD can cause an array of symptoms and discomfort.

Symptoms of Binocular Vision Dysfunction

Binocular Vision Dysfunction can cause a wide range of symptoms, varying in severity from person to person. Symptoms can be simple, like blurry vision and light sensitivity. Others may be more complex, leading to significant life disruption or disability.

Pain Symptoms

• Eye Strain (Asthenopia) and Fatigue: Experiencing tired or sore eyes, especially after prolonged visual tasks such as reading or using a computer.
• Eye Pain: Most people with BVD will experience eye pain from the slight misalignment of their eyes.
• Migraine Disorder: Frequent and severe headaches often accompanied by other sensory disturbances.
• Aching Face/“Sinus” Pain: Some people experience aching and pressure in their sinus area and mistake it for a sinus infection.
• Neck/Upper Back/Shoulder Pain: Neck and eye pain may occur when a head tilt is subconsciously used to help realign vision vertically, straining the muscles that support upright head posture.

Visual Symptoms

• Blurred Vision: Perhaps the most common BVD symptom. Blurry vision occurs when the eyes struggle to work together to produce a clear image.
• Double Vision (Diplopia): This common symptom occurs when the eyes are unable to maintain alignment to produce a single image. With double vision, there appear to be two of everything, or your vision has shadowed layers overlapping each other.
• Light Sensitivity (Photophobia): Individuals with BVD often experience discomfort or pain when exposed to bright lights or sunlight. This can result in squinting, eye watering, or even headaches, as the eyes strain to adjust to varying light conditions.
• Difficulty with Glare or Reflection: Glare from surfaces like screens, water, or car windows can be particularly challenging for those with BVD. The inability to properly filter or process reflected light may lead to visual fatigue and discomfort.
• Poor Depth Perception: People with BVD may struggle to accurately judge distances, making tasks like driving and playing sports difficult.
• Difficulty Maintaining Eye Contact: Many people with BVD avoid or struggle to maintain eye contact with others, as doing so can cause pain or discomfort.
• Head Tilt or Turn: A tendency to tilt or turn the head to one side to alleviate visual discomfort or to try to improve visual clarity.
• Difficulty with Night Vision: People often experience heightened difficulty seeing clearly in low-light conditions or at night.

Nonvisual Sensory Symptoms

• Dizziness/Lightheadedness: Some experience dizziness or lightheadedness caused by the brain’s struggle to process conflicting visual information from misaligned eyes.
• Nausea: Visual strain and misalignment caused by BVD can trigger nausea, especially during activities that require focus, such as reading, driving, or watching screens.
• Frequent Falling: People may experience balance and coordination challenges, leading to frequent falls. This can be due to issues with depth perception and spatial awareness, both of which are impacted by the eyes’ inability to work together.
• Disorientation: BVD can cause feelings of disorientation or confusion in space as the brain tries to make sense of conflicting visual inputs.
• Motion Sickness: Many people with BVD experience motion sickness in moving vehicles. The brain’s difficulty in processing visual and vestibular (balance) inputs simultaneously can make activities, like riding in cars, uncomfortable or nauseating.
• Visual Vertigo: A sensation of dizziness or spinning triggered by certain visual stimuli.

Reading Symptoms

• Difficulty with Reading: Struggling to read for extended periods due to visual strain. Words may appear to move on the page. Having difficulty focusing is also a common sign.
• Fatigue with Reading: Reading can be especially exhausting for those with BVD. The extra effort required to maintain focus can quickly lead to visual and mental fatigue.
• Rereading for Comprehension: People with BVD may need to reread passages frequently to fully understand them, as their eyes struggle to align and track the text accurately.
• Skipping Lines: BVD can make it difficult for the eyes to move smoothly across lines of text. This may cause unintentional skipping of lines or paragraphs.
• Words Running Together: Those with BVD may experience words blurring or merging on the page, making it hard to distinguish individual words.
• Closing/Covering One Eye: This temporarily eliminates the blurred/doubled image, making it easier to read.

Psychological Symptoms

• Restless Sleep Pattern: Difficulty sleeping or experiencing an irregular sleep pattern due to discomfort caused by BVD.
• Generalized Anxiety: Individuals with BVD may experience ongoing anxiety stemming from the daily struggle to interpret visual information accurately.
• Overwhelm in Crowds: Visual stimuli in crowded or busy environments can feel overwhelming for people with BVD, as their brains work harder to process complex visual input. This overstimulation can lead to feelings of stress, irritability, and even physical discomfort.
• Agoraphobia: Some individuals with BVD may develop a fear of leaving familiar or controlled environments. This is because they feel more vulnerable in open spaces or places where visual disorientation and imbalance are intensified. Avoidance behaviors and a reluctance to engage in daily activities outside the home often follow.
• Panic Attacks: BVD-related visual stress can trigger panic attacks, especially in situations that are visually or physically disorienting. Symptoms may include rapid heartbeat, sweating, shortness of breath, and a sudden feeling of fear or impending danger, often without a clear cause.
• Anxiety with Driving, Particularly on Highways: The visual stimulation from cars coming toward and around drivers with BVD is overwhelming.
• Anxiety Secondary to Visually Overstimulating Wallpaper/Carpet Patterns: Certain patterns are capable of triggering anxiety in those with BVD.
• Suicidal Thoughts: In severe cases, the chronic strain, discomfort, and psychological distress associated with BVD can contribute to feelings of hopelessness and suicidal thoughts.

Risk Factors

While anyone can develop BVD, risk factors that make it more likely include:

• Genetics: Family history of BVD or other eye alignment issues can increase susceptibility.
• Head Trauma: Concussions or head injuries can disrupt eye alignment, leading to BVD.
• Chronic Eye Strain: Prolonged use of digital screens or frequent near-focus activities can strain eye muscles, potentially exacerbating underlying misalignment.
• Existing Vision Conditions: Those with a history of strabismus (crossed eyes) or amblyopia (lazy eye) may be more prone to developing BVD.
• Age: Changes in eye muscle function or coordination with aging can contribute to BVD.
• Infectious Diseases: COVID-19, Lyme disease, and Mononucleosis (Mono) are examples of diseases that can lead to brain inflammation or acquired brain injury, increasing the risk of developing BVD.

Identifying and addressing these factors early can help manage or reduce the severity of BVD symptoms.

Living with BVD

Living with Binocular Vision Dysfunction impacts everyday experiences in ways many people may not expect. Common symptoms such as dizziness, headaches, and double vision can make even routine activities challenging.

For instance, reading can become tiring due to frequent loss of place on the page or words appearing to blur or shift. Driving, especially in traffic, can feel overwhelming because of difficulty focusing and accurately judging distances. Even walking or being away from home may feel disorienting, particularly in busy, visually complex environments like malls or grocery stores, crowds, or wide-open spaces.

People with BVD often experience persistent eye strain, fatigue, or tension. These symptoms are especially common after tasks that require focused vision, such as working on a computer or looking at digital screens. Even simple actions, such as descending stairs or moving through crowded spaces, can feel surprisingly difficult.

Daily life with BVD can be frustrating, especially since these symptoms can easily be mistaken for unrelated health issues, leading to delays in effective treatment. However, once diagnosed, tailored treatments like microprism glasses for BVD can significantly improve these symptoms and make daily life more comfortable.

Diagnosing BVD

Because symptoms can overlap with other conditions, it’s important to know how BVD is diagnosed:

• Symptom Questionnaire
• Health History Review
• Standard Vision Exam
• Full NeuroVisual™ Evaluation
• Trial Lens Fitting

The Role of a NeuroVisual™ Evaluation

A NeuroVisual™ Evaluation is a comprehensive, multi-part assessment designed to test both visual and physical coordination. This specialized examination is performed by NeuroVisual Medicine specialists with expertise in diagnosing and treating BVD. During the exam, the NeuroVisual Medicine specialist will assess the extent of misalignment in your eyes and precisely identify the amount of microprism correction needed to reduce symptoms.

BVD Treatment: Glasses with Microprism Lenses

A Solution for Binocular Vision Dysfunction

Binocular Vision Dysfunction can cause a multitude of distressing symptoms, impacting one’s quality of life. Fortunately, there are effective solutions to alleviate these symptoms, including the use of microprism glasses. In some cases, microprism glasses are more efficient than vision therapy. Microprism glasses are able to complete a course of treatment in approximately six to eight weeks, compared to vision therapy, which can run for many months. The result of microprism glasses is frequently more effective than vision therapy.

How Prism Glasses Work

Once the results of your NeuroVisual Evaluation are ready, the NeuroVisual specialist can prescribe microprism glasses tailored to your specific needs. Glasses with microprism lenses are specially designed eyeglasses that incorporate small amounts of prism. These glasses work by manipulating the way light enters your eyes, effectively correcting the misalignment. By realigning the images each eye receives, microprism glasses enable your brain to fuse them into a clear, focused image.

Benefits of Microprism Lenses

Microprism glasses offer several advantages for individuals with BVD, including:

• Relief from Symptoms of BVD: Microprism glasses can significantly reduce or even completely eliminate symptoms such as headaches, dizziness, double or overlapping vision, and eye strain.
• Improved Comfort: By aligning the images correctly, microprism glasses reduce the constant cycle of misalignment and realignment in your eyes, preventing eye muscle strain and discomfort.
• Enhanced Daily Functioning: With the help of microprism glasses, many individuals find that they can go about their daily activities more comfortably and with improved vision clarity.
• Neck and Shoulder Pain Reduction: Microprism glasses can eliminate the need for head tilting, which is a compensation strategy to alleviate the misalignment. As the tilt reduces and neck posture improves, muscle strain and neck pain are markedly reduced or eliminated.

Botox®: Not an Effective Treatment for BVD

OnabotulinumtoxinA (Botox®) is well-known for its cosmetic applications, but it also has medical uses, such as treating chronic migraines. While some may wonder if Botox® could help with Binocular Vision Dysfunction (BVD) due to its effectiveness in reducing muscular strain, it is not a common or recommended treatment for BVD symptoms.

Using Botox® for BVD would not address the underlying cause of the condition. Instead, Botox® temporarily relaxes muscles, which might help relieve some tension but would not realign the eyes or improve visual coordination.

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Common Misdiagnoses

Standard eye tests cannot diagnose Binocular Vision Dysfunction because they aren’t sensitive enough to detect minor misalignment. Since the eyes may seem to function normally, doctors often overlook vision problems as the cause unless a significant misalignment is found.

It’s common for people to have been diagnosed with a myriad of other conditions, and then find out that Binocular Vision Dysfunction was the true culprit. These other conditions include:

• ADD / ADHD
• Agoraphobia
• Anxiety / Panic Disorders
• Persistent Post-Concussive Symptoms
• Cervical Misalignment
• Meniere’s Disease
• BPPV (Benign Paroxysmal Positional Vertigo)
• Psychogenic Dizziness / Chronic Subjective Dizziness
• PPPD (Persistent Postural-Perceptual Dizziness)
• Vestibular Migraine / Migraine Associated Vertigo (MAV)
• Migraines
• MS (Multiple Sclerosis)
• Reading & Learning Disabilities
• Dyslexia
• Sinus Problems
• Stroke
• TMJ Disorders
• Traumatic brain injury (TBI)

How To Distinguish BVD from Other Conditions

Determining if you have BVD can be difficult, and it often starts by ruling out other serious conditions. If symptoms persist and the cause remains unclear, consider asking yourself the following:

• Have specialists been unable to diagnose or treat your symptoms, such as pain, dizziness, or light sensitivity?
• Have you been diagnosed with conditions that may mimic BVD?
• Did you suffer a concussion or brain injury, and have you had symptoms since?

If you suspect BVD, consult your eye doctor, as the condition can worsen. Be prepared with a full list of symptoms, how long you’ve been experiencing them, and why you think BVD may be the cause.

Additionally, you may wish to take the BVDQ™ Assessment, which can identify those who may have BVD and who would benefit from a NeuroVisual Medicine appointment.

Let’s Treat Your Binocular Vision Dysfunction

Are you familiar with some of these symptoms? If so, we provide a free online BVDQ™ Assessment to help you learn more about your symptoms and determine whether you should seek an appointment for a NeuroVisual Evaluation.

At NeuroVisual Medicine, your detailed and thorough evaluation goes above and beyond a regular eye exam. It is specifically designed to detect Binocular Vision Dysfunction. After the exam, any problems with alignment, far vision, or near vision will be addressed by a NeuroVisual Medicine specialist. Depending on your needs, treatment may include specialized microprism glasses designed to relieve symptoms and improve visual comfort.

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