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Questions and Answers
What is the primary function of the fovea in vision?
What is the primary function of the fovea in vision?
Dysconjugate gaze results in double vision.
Dysconjugate gaze results in double vision.
True
What type of fixation is required to follow a moving object with the eyes?
What type of fixation is required to follow a moving object with the eyes?
Pursuit fixation
The ability of the eyes to adjust focus to an object at varying distances is known as ________.
The ability of the eyes to adjust focus to an object at varying distances is known as ________.
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Match the following terms with their correct definitions:
Match the following terms with their correct definitions:
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What does recognition acuity primarily depend on?
What does recognition acuity primarily depend on?
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Hyperopia, or farsightedness, occurs when images are formed in front of the retina.
Hyperopia, or farsightedness, occurs when images are formed in front of the retina.
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What condition is characterized by a football-shaped cornea?
What condition is characterized by a football-shaped cornea?
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Myopia is also known as __________ due to its effect on seeing distant objects clearly.
Myopia is also known as __________ due to its effect on seeing distant objects clearly.
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Match the visual conditions with their descriptions:
Match the visual conditions with their descriptions:
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Which condition often leads to significant eyestrain due to the loss of accommodative abilities?
Which condition often leads to significant eyestrain due to the loss of accommodative abilities?
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Direction acuity refers to the ability to identify and name what we are seeing.
Direction acuity refers to the ability to identify and name what we are seeing.
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List two conditions affecting visual acuity.
List two conditions affecting visual acuity.
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What is the primary function of rods in the peripheral retina?
What is the primary function of rods in the peripheral retina?
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Cones are responsible for vision in low-light conditions.
Cones are responsible for vision in low-light conditions.
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What does a visual acuity measure?
What does a visual acuity measure?
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Visual acuity of 20/20 means you can see clearly at ____ feet what should normally be seen at that distance.
Visual acuity of 20/20 means you can see clearly at ____ feet what should normally be seen at that distance.
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In visual acuity testing, which type represents the ability to distinguish between two separate objects?
In visual acuity testing, which type represents the ability to distinguish between two separate objects?
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Having 10/10 vision guarantees perfect overall visual ability.
Having 10/10 vision guarantees perfect overall visual ability.
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Name the three primary types of cone sensitivity.
Name the three primary types of cone sensitivity.
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Visual acuity can help in detecting ocular diseases such as ________ and presbyopia.
Visual acuity can help in detecting ocular diseases such as ________ and presbyopia.
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Match the type of visual acuity with its definition:
Match the type of visual acuity with its definition:
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Which statement correctly describes the role of cones?
Which statement correctly describes the role of cones?
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What is a common treatment method for convergence excess?
What is a common treatment method for convergence excess?
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Divergence insufficiency involves the need for the eyes to diverge when looking at far objects.
Divergence insufficiency involves the need for the eyes to diverge when looking at far objects.
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What percentage of the population is affected by divergence excess?
What percentage of the population is affected by divergence excess?
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The treatment for divergence excess often involves shortening the medial rectus muscle of the eye to prevent excessive __________.
The treatment for divergence excess often involves shortening the medial rectus muscle of the eye to prevent excessive __________.
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Match the types of vergence disorders with their characteristics:
Match the types of vergence disorders with their characteristics:
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Which therapeutic option might be required in addition to glasses for convergence excess?
Which therapeutic option might be required in addition to glasses for convergence excess?
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Divergence excess is more prevalent in men, accounting for 60-70% of cases.
Divergence excess is more prevalent in men, accounting for 60-70% of cases.
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Describe the first signs of divergence excess in children.
Describe the first signs of divergence excess in children.
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During accommodative vergence, reflex accommodation is stimulated when attention shifts to the __________ material.
During accommodative vergence, reflex accommodation is stimulated when attention shifts to the __________ material.
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What is a surgical treatment method used for correcting divergence excess?
What is a surgical treatment method used for correcting divergence excess?
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What does convergence insufficiency primarily affect?
What does convergence insufficiency primarily affect?
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A person with convergence insufficiency can easily pass a 20/20 vision test.
A person with convergence insufficiency can easily pass a 20/20 vision test.
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What is intermittent exotropia?
What is intermittent exotropia?
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Convergence excess describes a condition where the eyes aim too ______ or in front of the object.
Convergence excess describes a condition where the eyes aim too ______ or in front of the object.
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Match the type of convergence disorder with its description:
Match the type of convergence disorder with its description:
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What is the most successful treatment for convergence insufficiency according to research?
What is the most successful treatment for convergence insufficiency according to research?
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Symptoms of convergence insufficiency can worsen due to stress.
Symptoms of convergence insufficiency can worsen due to stress.
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What might a child with convergence excess do to try to see better while reading?
What might a child with convergence excess do to try to see better while reading?
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A common symptom of convergence insufficiency is the experience of ______ or double vision.
A common symptom of convergence insufficiency is the experience of ______ or double vision.
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Which of the following could worsen symptoms of convergence insufficiency?
Which of the following could worsen symptoms of convergence insufficiency?
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Study Notes
Student Information
- Sandra Shamseddine is the student
- She has a Bachelor of Science (BS) in Optics and Optometry
- She has a Master of Science (MS) in Clinical Optometry
- This is for a Fall 2023/2024 class
Course Outcomes
- Students will learn about binocular vision and oculomotricity.
- Course connects binocular vision (BV) to psychomotor development.
- Students learn about eye problems, especially binocular vision and oculomotricity, and how they relate to other psychomotor skills.
General Eye Anatomy
- Cornea: Transparent front part of the eye; refracts light, focusing on the retina
- Pupil: Opening in the center of the iris; controls the amount of light entering the eye
- Crystalline Lens: Transparent biconvex structure behind the iris; focuses light onto the retina; Accommodation ability declines with age (presbyopia)
- Ciliary body: Produces aqueous humor, fluid nourishing the cornea
- Retina: The sensory membrane lining the back of the eyeball, contains photoreceptors
- Rods and Cones: Retinal photoreceptors (two types), responsible for light detection.
- Optic Nerve: Carries sensory impulses from the retina to the visual centers in the brain; part of the second cranial nerve
- Parts of the Eye: Image displays parts of eye - superior rectus, inferior rectus, optic disc, optic nerve, retina, fovea centralis, optic nerve, central retinal vein, central retinal artery, vitreous body, Ora serrata, ciliary body, posterior chamber, anterior chamber, cornea, lens, pupil, iris, zonules and sclera
Eye Anatomy Details
- Cornea: Transparent outer layer of the eye that refracts light.
- Pupil: Opening in the center of the iris that controls the amount of light that enters the eye.
- Crystalline Lens: Transparent structure that focuses light onto the retina.
- Ciliary Body: Structure that controls the shape of the lens.
- Retina: Sensory membrane at the back of the eye; contains photoreceptors.
- Optic Nerve: Carries visual signals from the retina to the brain.
Common Retinal Diseases Causing Low Vision
- Retinal tear
- Retinal detachment
- Diabetic retinopathy
- Macular degeneration
- Retinitis pigmentosa
- Glaucoma
- Optic Atrophy (partial or complete)
Cranial Nerves
- Six of the twelve cranial nerves directly innervate the eye and periocular tissues: CNII (optic nerve) CNIII (oculomotor) CNIV (trochlear) CNV (trigeminal) CNVI (abducens) CNVII (facial)
Extraocular Muscles
- Six muscles responsible for eye movements: 1). Superior rectus. 2). Inferior rectus. 3). Medial rectus. 4). Lateral rectus. 5). Superior oblique. 6). Inferior oblique.
Central Vs. Peripheral Retina
- Central retina, close to the fovea, is thicker than peripheral retina due to higher packing density of photoreceptors (especially cones).
- Central retina is primarily cone-dominated, while peripheral retina is rod-dominated.
What are Photoreceptors?
- Photoreceptors convert light into electrical energy through a chemical process.
- Signals move along the visual pathway
Central Vs. Peripheral Retina (cont.)
- Central vision: Details and colors
- Peripheral vision: Shapes, size, direction, movement of surroundings; helps us avoid obstacles
Key Differences (Rods and Cones)
- Rods: Highly sensitive to light, responsible for night vision, detect grayscale (no color)
- Cones: Less sensitive to light; responsible for color vision & detailed perception in bright light; three types (red, green, blue) to detect different colors.
Visual Acuity
- A measure of visual function by how well one sees details.
- Measures the patient's ability to see fine details; used to identify eye diseases.
Types of Visual Acuity
- Detecting/Visibility Acuity: simplest form; the ability to detect something
- Resolution Acuity: Measures the smallest separation the patient can perceive between two objects.
- Recognition Acuity:Ability to name what is seen by the action of the brain; dependent on visibility and resolution acuity
- Direction Acuity: Understanding an object's location, orientation, and tilt in space.
Near Visual Acuity
- Measures patients' ability to see at a typical reading distance
- Performed if a patient has difficulty reading or doing close-up work
Conditions Affecting Visual Acuity
- Optics: Refractive problems (myopia, hyperopia, astigmatism)
- Health: irregularities or clouding of ocular media (e.g., cataracts)
- Retina: swelling or loss of cells (e.g., macular degeneration)
- Optic nerve or brain: injury to neurons (e.g., stroke, tumor)
- Outside the visual system: mental retardation, autism, ADHD, nystagmus
Myopia/Nearsightedness
- Images are focused in front of the retina
- Caused by an elongated eye or strong refractive powers
- Usually begins in childhood and progressively worsens until adulthood.
Hyperopia/Farsightedness
- Images are focused behind the retina
- Caused by a shortened eye or weak refractive powers
- Individuals may still have clear vision at either distance or near depending on the degree of farsightedness and age.
- Can cause eyestrain
Astigmatism
- Cornea is not perfectly round
- Results in blurred vision at various distances
- Impacts about 30-40% of individuals who wear spectacles or contact lenses
Presbyopia
- Declining ability of the lens to focus on near objects; the lens hardens
- Usually develops around age 40 or 45, leading to the need for reading glasses
Visual Pathway
- Optic nerve --> Optic chiasm --> Optic tract --> Lateral Geniculate Nuclei --> Optic radiation --> Primary Visual Cortex
Parietal Association Cortex
- Enables individuals to perform reading, writing, and solving mathematical problems
- Sensory inputs from one side of the body are processed by the opposite side of the brain in the same way as from the eyes.
Visual Field Defects (Diagram)
- Types and cause of vision loss
Visual Association Areas
- Visual information from the primary visual cortex is relayed to other areas for further processing. The dorsal and ventral streams process spatial and object features, respectively.
Dorsal Stream
- Processes information about where visual objects are in space (location) in combination with object movement
Ventral Stream
- Processes information about the characteristics of visual objects (form, identification, and color) -recognizes objects and colors, reads text, learns and remembers visual objects, and processes information about "what" of a visual stimulus
Alexia
- Partial or complete inability to read
- Subtype distinctions exist, but all typically involve slow or impossible reading with impaired comprehension.
- Stroke is the commonest cause but other forms of neurological disease can also cause alexia
Vision and Learning
- Vision issues are the most common cause of learning problems in children
- Approximately 25% of school-aged children have significant vision-related learning problems
Visual Perception
- Ability to organize visual information from one's surroundings to understand it
- Active process of extracting information aided by visible light. Visual system is comprised pf many physiological components and is a complex interaction of cognitive science, psychology, neuroscience and molecular biology
Visual Perceptual Processing Categories
- Visual discrimination
- Visual figure-ground
- Visual closure
- Visual memory
- Visual sequential memory
- Visual form constancy
- Visual spatial relationships
- Visualization
- Visual sequencing
- Visual attention/span
Visual Discrimination
- Ability to recognize similarities and differences in shapes, letters, colors, and settings (ex: hot vs. hut)
- Fundamental component of elementary reading skills and identifying and separating visual patterns
Visual Figure Ground
- Ability to distinguish an object from its background despite clutter or distractions.
- Separates the stimuli and allows us to understand details in a visual field
Visual Closure
- Recognizing a complete object/image from incomplete or partial information.
- Completing the image via mental filling in of missing pieces.
Visual Memory
- Recognizing and recalling characteristics of previously viewed images
Visual Form Constancy
- Ability to recognize objects regardless of their size, shape, or orientation
Visual Spatial Skills
- Understanding spatial concepts and organizing visual space
- Recognizing shapes/characters without regards to their orientation
Visual Sequencing
- Perceiving visual information that's arranged in a sequence and recalling the order of events
Visualization
- Creating a mental image of objects/information
- Recognizing the complete image from incomplete data
Visual Attention/Attention Span
- Ability to process information within complex visual fields
- Selecting important data and ignoring irrelevant information by focusing on the required/relevant data within the visual space.
Visual Analysis Dysfunctions
- Difficulties with visual discrimination
- Difficulties with form perception/spatial relationships
- Difficulties with form constancy
- Difficulties with figure-ground segregation
- Difficulties with visual attention/attention span
- Difficulties with visual memory/visualization
Accommodation
- The process by which the eye adjusts its focus to clearly see objects at different distances
Accommodative Problems (Symptoms)
- Eye discomfort/headaches, especially frontal headaches when performing close-up work
- Squinting, blinking, and rubbing eyes
- Difficulty copying written material from a board
- Blurred vision when reading small print
- Visual acuity worsening as the day progresses
- Reduced attention span while performing close-up tasks
- Poor reading comprehension
Types of Accommodative Disorders
- III-sustained accommodation
- Accommodative excess
- Accommodative insufficiency
- Paralysis of accommodation
- Spasm of accommodation
Types of Accommodative Disorders (cont)
- Ill-sustained accommodation
- Accommodative excess: focusing on objects closer than they should be.
- Accommodative insufficiency: problems with focusing objects closer than they should be.
Types of Accommodative Disorders (cont.)
- Accommodative infacility:
- Accommodative paresis:
- Accommodative spasm:
Ocular Motor Skills
- Coordination of eye movement, including tracking, fixation, and saccades
Eye Movements and Reading
- Progressive, regressive, and back-to-line movements for orienting to new letters/sentences
- Micromovements for extracting and analyzing the visual information during fixation
Fixation and Reading
- Maintaining steady gaze on a point to extract visual details from that particular spot/area
Saccades
- Rapid eye movements that shift the eyes from one target to another
- Bring objects of interest into focus on the fovea
- Clinically tested by having the patient make eye movements
Saccades and Reading
- Precise eye movement jerks are important in visual processing and reading
Pursuits
- Smooth eye movements that tracking a moving object and maintaining the image on the fovea
- Affected by age and medication
- Corrective saccades needed to get the eyes back on target
Pursuits Testing
- Testing smooth pursuit by having a patient follow a moving object
- Observe eyes at rest to look for anomalies.
Fixation
- Ability to accurately aim the eyes at a particular spot (monocularly/binocularly)
- Essential for tasks requiring focusing on stationary objects
Saccadic Fixation
- Saccadic fixation dysfunction can cause symptoms to the patient.
- Important for reading in which the eyes must be accurately focused at a specific spot
Pursuits Fixation
- Ability to follow moving objects with eyes.
- Requires split-second timing for the brain to process and track the movement of the object
Vergence and Going Back to the Line
- Includes eye movements to look at objects at different depths/depths. Visual system movement for different depths
Interpretation (Foveal and Parafoveal Treatment)
- Foveal and parafoveal treatment
- Fovea (cone supported): high-acuity vision at the center
- Parafoveal and peripheral (Rods supported): processing the length of words
Areas of Visual Span
Perceptual Span (Child/Adult)
- Foveal vision is clear to allow quick visual fixations of nearby objects.
Role of Attention in Foveal and Parafoveal Treatment
- Attentional filters help reduce the impact of parafoveal information on foveal information
Remedies/Readings
- Methods of enhancing readings, including adjustments to fonts, spacing, and lines.
Symptoms for Binocular Disorders
- Eye strain with prolonged reading
- Headaches, blurred or double vision
- Difficulty concentrating
- Short attention span
- Avoiding near work
- Poor sports performance
- Dizziness or motion sickness
- Trouble remembering what was read
- Words may appear to move, float, jump
Convergence and Divergence (Eye Teaming)
- Convergence: Inward movement of the eyes when looking at nearby objects
- Divergence: Outward movement of the eyes when looking at faraway objects
- The brain constantly samples the visual environment and adjusts the eye movements for optimal focus
Convergence Insufficiency
- A common problem with the development of these skills, eyes not coming together when looking closely.
- Can lead to blurriness, difficulty focusing, and eye strain
Convergence Excess
- Eyes aim too close or in front of objects, resulting in blurred vision, confusion, or fatigue
- Common in near-work tasks, such as reading and writing.
Types of Vergence Disorders (Cont.)
- Divergence insufficiency
- Divergence excess
Treatment Methods (Convergence Insufficiency)
Treatment Methods (Convergence Excess)
Divergence Insufficiency
- Eyes tend to diverge excessively when looking at distant objects, causing blur or double vision
- Unusual form of strabismus and diplopia only at distance
Treatment Methods (Divergence Excess)
Stereopsis
- Binocular depth perception
- The ability of the two eyes to fuse separate images to create a 3-dimensional image
Stereopsis (cont.)
- Important component of binocular vision; crucial for depth perception
Amblyopia
- Poor vision due to incomplete visual system development
- Caused by an imbalance in the eyes, or by damage causing a blurry image
Amblyopia Categories
- Pattern deprivation: Light enters but no clear/focused image
- Optical defocus (poor image quality): e.g. poor prescription of spectacles
- Strabismus (poor eye coordination): eyes do not align properly
Amblyopia Therapy
- Early intervention during the sensitive period is important or it will result in poor vision in one or both eyes.
- Therapy and glasses may be effective
Suppression
- Brain ignores signals from a blurry eye to avoid confusion
Suppression (cont.)
- Common in amblyopia, specifically refractive amblyopia
- If left untreated, can lead to permanent vision loss
Suppression (cont.)
- Suppression involves the brain ignoring the visual input from one eye to avoid the confusion of two separate images from different eyes.
Vision Therapy
- A therapy program designated to help patients learn to use the visual system more effectively
- Conditions needing therapy may include binocular disorders, loss of binocularity, and/or developmental/perceptual difficulties.
- May help restore proper visual function following loss of brain function if a closed-head injury, or other traumatic events such as a stroke.
Color Vision
- Involves the perception of colors via photoreceptors called cones
- Detected based on wavelengths
Color Vision (cont.)
- Cone types: Red, green, blue
Color Vision (cont.)
- Ishihara color test for identifying color blindness and deficiencies
Contrast Sensitivity
- Ability to discriminate subtle differences in light/shadow.
- Important for situations involving low light, fog, or glare
Perception of Movement
- The visual system processes and recognizes movements through eye tracking.
Impact of Proper Assessment and Optometric Intervention
- Improving visual comfort, efficiency, and concentration.
- Visual system improvement that results in improved daily visual tasks
- Increase in strength and stamina regarding the visual system that impact the individual academically, confidently, and positively regarding their self-esteem.
Model of Visual Perceptual Processing
- A hierarchical model outlining the steps for visual information processing and visual perception
- This multi-step process begins with input via the eyes for visual information which then moves through the brain.
Visual Spatial Skills
- Understanding the locations of objects and relations with the body (laterality, directionality, and bilateral integration)
Pediatric Eye Problems (Overview)
- Cataracts
- Glaucoma
- Cortical Visual Impairment (CVI)
- Developmental abnormalities
Pediatric Cataracts
- Cloudiness or opacification of the eye lens; occurs in children (infants/young children)
- Early identification and correction are key to prevent vision impairment
Pediatric Glaucoma
- High eye pressure can damage the optic nerve, leading to permanent vision loss.
- Common in newborns/children
Cortical Visual Impairment (CVI)
- Abnormalities in the brain's visual processing centers
- Eyes may function normally but interpretation is lost or impaired due to issues in the visual processing areas within the brain.
Developmental Abnormalities (Eye Problems)
- Coloboma, microphthalmia (small eye), optic nerve hypoplasia
Vision and Tests
- Visual tests to evaluate different components of the eye
NEPSY Fleches and NEPSY Maison tests for visual functions
- NEPSY Fleches: evaluates visual figure ground, pursuits, and peripheral awareness, and visual discrimination acuity.
- NEPSY Maison: evaluates recognition tasks, pursuits, and the crowding effect
NEPSY Cubes and Stereopsis tests - for visual functions.
TEA-CH tests - for visual functions (contrast, saccadic ability, and recognition)
REY tests: tests Visual Spatial capacity and visual memory.
DTVP3 tests (Visual and Motor coordination, Pursuits, Crowding effect, and Contrast)
Visual Processing Model Summary
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Description
Test your knowledge on the anatomy and functions of the eye. This quiz covers aspects such as visual acuity, eye conditions, and the roles of different types of photoreceptors. Perfect for students and enthusiasts of human biology and vision science.
