36 Questions
According to the Accommodative Lag Theory (2000), what stimulates eye growth?
Relative hyperopia
The level of defocus present on the image affects the number of microsaccades produced.
False
What class of fixational eye movement is the largest?
Microsaccades
Excessive blinking can lead to a condition known as _____
Blepharospasm
What is the focus of the image in the peripheral refraction theory?
Behind the retina
What is the result of under-accommodation during near work according to the Accommodative Lag Theory?
Relative hyperopia
What type of retinal image is associated with the parvo?
Foveal image
What happens to vision during saccades?
It is degraded
What is the effect of myopia on microsaccades generation?
Myopes produce more microsaccades
What is lid lag?
A condition where eyelids fail to lower as gaze is lowered
What is the purpose of fixational eye movements?
To ensure that vision does not fade during fixation
What is essential blepharospasm?
A type of blepharospasm with no identifiable cause
What can modulate fixational eye movement?
Both environmental and cognitive factors
What is the result of treating myopia with plus at near according to the Accommodative Lag Theory?
Slowing of myopia progression
What is oculomotor apraxia sometimes accompanied by?
Excessive blinking
What is a possible cause of insufficient closure?
All of the above
What is the explanation for the stability of perception despite the existence of fixational eye movements?
A hypothetical microsaccadic suppression mechanism
What is Hering's law related to?
Lid retraction in the eye opposite to a ptosis
What is ocular blepharospasm caused by?
Ocular disease
What can cause excessive blinking?
Ocular disease
What is the consequence of under-accommodation during near work according to the Accommodative Lag Theory?
Image focused behind the retina at fovea
What is the primary difference between the Peripheral Refraction Theory and the Accommodative Lag Theory?
The peripheral refraction theory focuses on peripheral image formation
What is the role of microsaccades in the context of fixational eye movements?
To generate small displacements of the eyeballs
What is the relationship between myopia and microsaccades?
Myopes produce more microsaccades than emmetropes
What type of retinal image is associated with the magno?
Periphery image
What can modulate fixational eye movements?
Both environmental and cognitive factors
What happens to our visual experience during fixation?
It is enhanced.
What is the explanation for the stability of perception despite the existence of fixational eye movements?
A hypothetical microsaccadic suppression mechanism
What is the treatment approach according to the Peripheral Refraction Theory?
Treat with plus lenses in the periphery
What is the result of a problem with vertical gaze centers?
Lid lag
What is an example of Hering's law?
Lid retraction in the eye opposite to a ptosis
What is excessive closure of the eyelid associated with?
Blepharospasm
What is the cause of ocular blepharospasm?
Ocular disease
What is a possible cause of insufficient closure of the eyelid?
All of the above
What is oculomotor apraxia sometimes accompanied by?
Excessive blinking
During which phase of eye movement is vision degraded?
Saccades
Study Notes
Eye's Axial Length Control Theories
- Accommodative Lag Theory (2000): proposes that under-accommodation during near work leads to image focusing behind the retina at the fovea, causing relative hyperopia that stimulates eye growth, and can be treated with plus lenses at near, such as bifocals or PALs.
- Peripheral Refraction Theory (2020): suggests that shorter off-axis eye length and image focus behind the retina in the periphery leads to relative hyperopia, stimulating eye growth, and can be treated with plus lenses in the periphery.
Sampling of Retinal Images
- Parvo (fovea) and Magno (periphery) are two different types of sampling.
Fixational Eye Movements
- Small displacements of the eyeballs (tremor, drifts, microsaccades) ensure vision does not fade during fixation.
- Despite fixational eye movements, perception remains stable due to a hypothetical microsaccadic suppression mechanism.
- Fixational eye movements can be modulated by environmental (illumination conditions) and cognitive (attention) factors.
Saccades and Eye Movements
- Vision is degraded during saccades.
- Velocity (vertical gaze centers) problems can cause lid lag, such as in extrapyramidal syndromes.
- Lid retraction in the eye opposite to a ptosis is not a disorder, but an example of Hering's law.
Blepharospasm and Insufficient Closure
- Excessive closure (blepharospasm) can be due to ocular disease (e.g., dry eyes, uveitis, keratitis) or idiopathic essential blepharospasm.
- Insufficient closure can be caused by diseases affecting the facial nerve nucleus (somatic motor fibers), basal ganglia (Parkinson's), or frontal lobe lesions, affecting the ability to wink.
Eye's Axial Length Control Theories
- Accommodative Lag Theory (2000): proposes that under-accommodation during near work leads to image focusing behind the retina at the fovea, causing relative hyperopia that stimulates eye growth, and can be treated with plus lenses at near, such as bifocals or PALs.
- Peripheral Refraction Theory (2020): suggests that shorter off-axis eye length and image focus behind the retina in the periphery leads to relative hyperopia, stimulating eye growth, and can be treated with plus lenses in the periphery.
Sampling of Retinal Images
- Parvo (fovea) and Magno (periphery) are two different types of sampling.
Fixational Eye Movements
- Small displacements of the eyeballs (tremor, drifts, microsaccades) ensure vision does not fade during fixation.
- Despite fixational eye movements, perception remains stable due to a hypothetical microsaccadic suppression mechanism.
- Fixational eye movements can be modulated by environmental (illumination conditions) and cognitive (attention) factors.
Saccades and Eye Movements
- Vision is degraded during saccades.
- Velocity (vertical gaze centers) problems can cause lid lag, such as in extrapyramidal syndromes.
- Lid retraction in the eye opposite to a ptosis is not a disorder, but an example of Hering's law.
Blepharospasm and Insufficient Closure
- Excessive closure (blepharospasm) can be due to ocular disease (e.g., dry eyes, uveitis, keratitis) or idiopathic essential blepharospasm.
- Insufficient closure can be caused by diseases affecting the facial nerve nucleus (somatic motor fibers), basal ganglia (Parkinson's), or frontal lobe lesions, affecting the ability to wink.
Eye's Axial Length Control Theories
- Accommodative Lag Theory (2000): proposes that under-accommodation during near work leads to image focusing behind the retina at the fovea, causing relative hyperopia that stimulates eye growth, and can be treated with plus lenses at near, such as bifocals or PALs.
- Peripheral Refraction Theory (2020): suggests that shorter off-axis eye length and image focus behind the retina in the periphery leads to relative hyperopia, stimulating eye growth, and can be treated with plus lenses in the periphery.
Sampling of Retinal Images
- Parvo (fovea) and Magno (periphery) are two different types of sampling.
Fixational Eye Movements
- Small displacements of the eyeballs (tremor, drifts, microsaccades) ensure vision does not fade during fixation.
- Despite fixational eye movements, perception remains stable due to a hypothetical microsaccadic suppression mechanism.
- Fixational eye movements can be modulated by environmental (illumination conditions) and cognitive (attention) factors.
Saccades and Eye Movements
- Vision is degraded during saccades.
- Velocity (vertical gaze centers) problems can cause lid lag, such as in extrapyramidal syndromes.
- Lid retraction in the eye opposite to a ptosis is not a disorder, but an example of Hering's law.
Blepharospasm and Insufficient Closure
- Excessive closure (blepharospasm) can be due to ocular disease (e.g., dry eyes, uveitis, keratitis) or idiopathic essential blepharospasm.
- Insufficient closure can be caused by diseases affecting the facial nerve nucleus (somatic motor fibers), basal ganglia (Parkinson's), or frontal lobe lesions, affecting the ability to wink.
This quiz covers two theories of eye's axial length control: Accommodative Lag Theory and Peripheral Refraction Theory, including their explanations and treatments.
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