Overview

Diplopia, commonly known as double vision, occurs when a person sees two images of a single object. This vision impairment is usually temporary but can indicate a more serious health condition. It can significantly impact daily activities such as reading, driving, or navigating environments safely by affecting a person's depth perception. Diplopia can occur due to neurological damage, such as disruptions to the brain's cranial nerves (3, 4, or 6) or visual pathways.

Signs & Symptoms

• Reports seeing double images, either horizontally or vertically

• Reports of blurred or shadowed vision

• Experiences headaches, eye strain, or fatigue

• Struggles with depth perception

• Misses or overshoots targets during reaching tasks

• Closes or squints one eye (drooping eyelids)

• Adjusts the position of tasks or head/body

• Reports symptoms of nausea, headache, dizziness, or eye discomfort

Types of Diplopia

Monocular vs. Binocular
Diplopia can occur in one eye (monocular) or both eyes (binocular). Binocular diplopia is more common among individuals who have suffered a TBI and is often related to strabismus, a misalignment of the eyes (Scroll down for photo reference of different types of strabismus)

Horizontal vs. Vertical

• Vertical Diplopia: Characterized by objects appearing split one on top of the other

• Horizontal Diplopia: Characterized by objects appearing split side to side

Both types of diplopia can occur in one eye or both

Impact on Occupational Participation

• Difficulty reading or driving

• Navigating the environment

• Challenges in preparing meals

• Participation in recreational activities

• Increase the risk of falling due to misjudging steps or curbs

Overview

Nystagmus is a visual deficit described most commonly as both eyes moving rapidly, uncontrolled, and repetitively. It is frequently reported following a TBI from motor vehicle accidents or in veterans who suffered from blast explosions

Motor vehicle collisions can lead to both vestibular and sensory disturbances, while blast exposure can result in vestibular dysfunction among veterans

Types of Nystagmus

• Horizontal Nystagmus: Eyes move side to side

• Vertical Nystagmus: Eyes move up and down

• Rotary or Torsional Nystagmus: Eyes move in a circular motion

• Jerk Nystagmus: One-direction drift with a corrective rapid movement in the opposite direction

• Pendular Nystagmus: Steady back-and-forth motion, similar to a pendulum

Signs & Symptoms

• Blurry or shaky vision

• Difficulties with balance and coordination

• Photophobia (sensitivity to light)

• Dizziness, nausea, or vertigo (the feeling of spinning or movement)

Impact on Occupations

• Difficulty reading or using electronic devices

• Challenges with safe navigation and mobility

• Increased fall risk due to impaired balance and spatial awareness

• Difficulty with tasks requiring sustained attention

• Avoidance of recreational activities involving motion (e.g., sports or driving)

• Discomfort in crowded or busy environments

Overview

Smooth pursuit eye movements allow us to track moving objects using visual motion processing, sensorimotor coordination, and cognitive functions (Lencer, R., & Trillenberg, P., 2008). Deficits in smooth pursuit movements are common following a TBI and are indicated if the patient is unable to coordinate both eyes to track visual objects across their visual fields while keeping their head still. Smooth pursuit eye movements (SPEM) are essential for tracking moving stimuli in daily life, such as cars in traffic or moving players in sports

Signs & Symptoms

• Inability to smoothly follow moving objects (jerky eye movements)

• Replacing smooth tracking with rapid saccades (small jumps between focus points)

• Eye strain or fatigue during visual activities

• Reports blurred vision when tracking moving objects

• Difficulty with reading (loss of place, repetition, or skipping words and sentences while reading)

• Challenges in transitioning visual focus between objects

• Excessive head movements and abnormal postural adaptations to focus the eyes such as moving the head to read

• Dizziness, nausea, or headaches triggered by motion-related activities

• Inaccurate hand-eye coordination

Types of Smooth Pursuit Deficits

• Horizontal Smooth Pursuit: Difficulty tracking objects moving side-to-side

• Vertical Smooth Pursuit: Challenges following objects moving up and down

• Diagonal Smooth Pursuit: Difficulty tracking objects moving along a diagonal plane, combining both horizontal and vertical motion

• Circular Smooth Pursuit: Trouble maintaining focus on objects moving in a circular motion

Impact on Occupational Participation

• Driving (tracking moving vehicles or pedestrians)

• Reading

• Navigating the environment due to difficulty tracking moving objects or navigating crowded spaces.

• Increased risk of falls due to misjudging steps, curbs, or other obstacles while walking

• Challenges in eye-hand coordination activities or sports (catching, throwing, or kicking balls)

• Struggles with participating in leisure activities (watching movies, TV, playing games, or doing arts and crafts due to tracking impairments)

• Challenges in switching focus when following written directions (looking at a recipe, then back to the cooking task)

Overview

Visual saccades are rapid and precise eye movements in which both eyes shift focus during visual scanning or a visual search between two or more points/objects. They are described and tested in the horizontal and vertical directions. Saccades are primarily controlled at the cerebellar level. Deficits can lead to decreased performance in visual accuracy, speed, and involuntary eye movements. Visual saccades are essential for individuals to participate in activities like reading, searching for a person in a crowded room, and many other daily tasks that require visual scanning.

Signs & Symptoms

• Difficulty tracking between two or more stationary objects

• Delayed or slowed eye movements during scanning tasks

• Overshooting or undershooting visual targets (poor eye-hand coordination)

• Loss of place while reading (skipping words or lines)

• Reports of dizziness, nausea, or headaches during tasks that require a lot of visual scanning

• Reduced ability to focus or maintain attention on tasks

Common Types of Saccadic Deficits

• Saccade initiation: An individual is unable to generate saccadic eye movements after prompting

• Range of motion: An individual lacks the full range of movement in visual scanning (find a different way to say this)

• Conjugacy of saccades: Both eyes do not move in unison

• Speed: One or both eyes are delayed or slower in movement

• Intrusion or oscillation: One or both eyes display signs of unwanted or jerky eye movements

Impact on Occupational Participation

• Reading or writing (difficulties having to shift focus between lines and words)

• Watching a sporting event

• Home management tasks (such as cleaning and cooking)

• Navigating unfamiliar places (scanning for road signs or using a map)

• Grocery shopping (difficulty scanning shelves or grocery lists)

• Driving (difficulty scanning between street signs, lights, or other cars)

• Social Participation (Engaging in conversation with two or more people)

Overview 

Convergence and accommodation insufficiencies of binocular vision are commonly reported following a mild TBI

• Convergence Insufficiency: A visual impairment affecting an individual's ability to sustain convergence and maintain medial eye alignment on near objects. The brainstem is responsible for controlling convergence. Eyes may drift outward when focusing on close objects, leading to binocular vision problems and double vision

• Accommodation Insufficiency: A visual impairment impacting an individual's ability to focus clearly on near or far objects for extended periods. Patients often report blurred vision when shifting focus between near and far objects. Accommodation insufficiency is caused by weak or insufficient lens adjustment

Signs & Symptoms

• Weak or tired eyes during near tasks (reading or close-up work)

• Difficulty concentrating

• Headaches, dizziness, or nausea with visual activities

• Diplopia (double vision) when looking at near objects

• Difficulty focusing on near objects (blurred or shadowed vision)

• Lack of judgment of distances

• Difficulty maintaining eye contact

• Eye strain or fatigue during reading or close-up work

• Difficulty transitioning focus between near and far objects

Impact on Occupational Participation

• Difficulty with reading, working, using a computer, or other small electronic devices

• Challenges navigating the environment

• Difficulty with grooming and self-care tasks (e.g., shaving, applying makeup, trimming nails)

• Avoidance of near tasks due to headaches and discomfort

• Difficulty completing schoolwork (e.g., note-taking and reading)

• Challenges with household management (e.g., organizing tasks, reading recipes, paying bills)

• Limited engagement in leisure activities (e.g., crafting or knitting)

Overview
Visual field deficits (VFDs) refer to the loss of a portion of the visual field, affecting how much a person can see when looking straight ahead and focused on a central point. 

• Normal binocular visual field 

  • Spans approximately 160 degrees

• Normal monocular visual field 

  • 60 degrees superiorly

  • 75 degrees inferiorly, 60 degrees nasally

  • 100 degrees temporally

• Normal peripheral vertical vision 

  • 45 degrees

• Normal horizontal/temporal peripheral vision 

  • 85 degrees

VFDs often result from damage to the optic pathways due to traumatic brain injury (TBI) after motor vehicle accidents or blast injuries. Common types include homonymous hemianopia, quadrantanopia, and peripheral field loss.

Signs & Symptoms

• Cannot recognize or takes longer to notice the stimulus in the visual field

• Colliding or bumping into things 

• Difficulties with reading and writing (skewed or drifted writing)

• Requires head or body scanning to identify objects

• Disorientation or balance issues

• Misalignments in body posture to the left or right

• Struggles to locate items in cluttered environments

Common Types of Visual Field Deficits

• Homonymous Hemianopia: Loss of vision on the same side of both eyes (left or right). Often due to damage to the optic tract, optic radiation, or occipital lobe

• Quadrantanopia: Loss of vision in one quadrant (one-fourth) in both eyes' visual field. The eye is broken up between 2 top quadrants (left and right) and 2 bottom quadrants (left and right). Often due to localized optic pathway damage

• Altitudinal Defect: Loss of vision in the upper or lower quadrants in both eyes

• Peripheral Field Loss: Vision loss is described as tunnel vision in one or both eyes. Often due to anoxic brain injury or retinal conditions

Impact on Occupational Participation

• Driving and functional mobility

• Self-care and homemaking tasks

• Work, education, and leisure activities that require reading or writing