Podcast
Questions and Answers
What is the primary purpose of the swinging flashlight test?
What is the primary purpose of the swinging flashlight test?
Which of the following occurs during the near reflex test?
Which of the following occurs during the near reflex test?
In the swinging flashlight test, what should happen to both pupils when the light is directed at one eye?
In the swinging flashlight test, what should happen to both pupils when the light is directed at one eye?
What happens when there is damage to the afferent pathway in relation to the pupil response?
What happens when there is damage to the afferent pathway in relation to the pupil response?
Signup and view all the answers
Which response is considered the weakest during the near reflex test?
Which response is considered the weakest during the near reflex test?
Signup and view all the answers
What is the role of the Edinger-Westphal nucleus in the eye's reflexes?
What is the role of the Edinger-Westphal nucleus in the eye's reflexes?
Signup and view all the answers
What does convergence induce in conjunction with pupil constriction?
What does convergence induce in conjunction with pupil constriction?
Signup and view all the answers
How long should the light be kept on each eye during the swinging flashlight test?
How long should the light be kept on each eye during the swinging flashlight test?
Signup and view all the answers
What is the expected response when light is shone into the effected eye in the case of afferent pathway damage?
What is the expected response when light is shone into the effected eye in the case of afferent pathway damage?
Signup and view all the answers
What differentiates the responses of the effected eye from the non-effected eye when light is shone at both?
What differentiates the responses of the effected eye from the non-effected eye when light is shone at both?
Signup and view all the answers
What pathology is likely to block impulses reaching the optic chiasm?
What pathology is likely to block impulses reaching the optic chiasm?
Signup and view all the answers
In the swinging flashlight test, what response would be expected from the non-effected eye?
In the swinging flashlight test, what response would be expected from the non-effected eye?
Signup and view all the answers
Which response will remain normal despite the damage to the afferent pathway?
Which response will remain normal despite the damage to the afferent pathway?
Signup and view all the answers
How does a lesion of the optic nerve affect pupil reactions?
How does a lesion of the optic nerve affect pupil reactions?
Signup and view all the answers
Which statement accurately describes the light response of the effected eye in relation to the consensual response?
Which statement accurately describes the light response of the effected eye in relation to the consensual response?
Signup and view all the answers
What is the role of the pretectal nuclei in the reflex pathway discussed?
What is the role of the pretectal nuclei in the reflex pathway discussed?
Signup and view all the answers
What should be observed during the initial observation step for anisocoria?
What should be observed during the initial observation step for anisocoria?
Signup and view all the answers
What characterizes the direct response when light is shone into a healthy eye?
What characterizes the direct response when light is shone into a healthy eye?
Signup and view all the answers
In assessing the consensual response, what should occur in the contralateral pupil?
In assessing the consensual response, what should occur in the contralateral pupil?
Signup and view all the answers
When evaluating anisocoria, what distinguishes physiological anisocoria from pathological anisocoria?
When evaluating anisocoria, what distinguishes physiological anisocoria from pathological anisocoria?
Signup and view all the answers
What procedure is used to evaluate 'pupillary escape' or the Marcus Gunn response?
What procedure is used to evaluate 'pupillary escape' or the Marcus Gunn response?
Signup and view all the answers
During the direct response examination, which condition should be fulfilled for accurate assessment?
During the direct response examination, which condition should be fulfilled for accurate assessment?
Signup and view all the answers
What is an important step when performing the swinging flashlight test?
What is an important step when performing the swinging flashlight test?
Signup and view all the answers
In which situation would the near reflex test be indicated?
In which situation would the near reflex test be indicated?
Signup and view all the answers
Which pathway carries information towards the central nervous system?
Which pathway carries information towards the central nervous system?
Signup and view all the answers
What type of muscle is primarily responsible for pupil dilation?
What type of muscle is primarily responsible for pupil dilation?
Signup and view all the answers
Which type of fiber innervates the sphincter muscle of the iris?
Which type of fiber innervates the sphincter muscle of the iris?
Signup and view all the answers
Which condition would most likely cause the pupil to dilate?
Which condition would most likely cause the pupil to dilate?
Signup and view all the answers
Anisocoria is defined as:
Anisocoria is defined as:
Signup and view all the answers
In bright lighting conditions, the primary action of the sphincter muscle is to:
In bright lighting conditions, the primary action of the sphincter muscle is to:
Signup and view all the answers
Which type of receptor is stimulated by Acetylcholine in the parasympathetic pathway?
Which type of receptor is stimulated by Acetylcholine in the parasympathetic pathway?
Signup and view all the answers
What is the range of normal pupil size in ambient light conditions?
What is the range of normal pupil size in ambient light conditions?
Signup and view all the answers
What effect does a lesion along the afferent pathway have on the corneal reflex?
What effect does a lesion along the afferent pathway have on the corneal reflex?
Signup and view all the answers
Which of the following substances is a sympathomimetic that can cause pupil dilation?
Which of the following substances is a sympathomimetic that can cause pupil dilation?
Signup and view all the answers
What is the primary purpose of testing pupil function?
What is the primary purpose of testing pupil function?
Signup and view all the answers
Where does central processing occur in the afferent visual pathway?
Where does central processing occur in the afferent visual pathway?
Signup and view all the answers
What effect does the dilator muscle have under dark lighting conditions?
What effect does the dilator muscle have under dark lighting conditions?
Signup and view all the answers
What is the condition characterized by a fixed dilated pupil and absent accommodation due to damage at the pre-ganglionic stage?
What is the condition characterized by a fixed dilated pupil and absent accommodation due to damage at the pre-ganglionic stage?
Signup and view all the answers
In which syndrome does the pupil react normally to light despite damage to the sympathetic pathway?
In which syndrome does the pupil react normally to light despite damage to the sympathetic pathway?
Signup and view all the answers
What is a common cause for Horner's syndrome?
What is a common cause for Horner's syndrome?
Signup and view all the answers
What pupil response is often seen in individuals with Adie's tonic pupil in bright conditions?
What pupil response is often seen in individuals with Adie's tonic pupil in bright conditions?
Signup and view all the answers
Which of the following is a characteristic of the Argyll Robertson pupil?
Which of the following is a characteristic of the Argyll Robertson pupil?
Signup and view all the answers
What results from damage to the ciliary ganglion or postganglionic fibers of the short ciliary nerve?
What results from damage to the ciliary ganglion or postganglionic fibers of the short ciliary nerve?
Signup and view all the answers
In the swinging flashlight test, what would you expect in a patient with Horner's syndrome?
In the swinging flashlight test, what would you expect in a patient with Horner's syndrome?
Signup and view all the answers
Which pupil condition is characterized by slow and tonic near reaction when looking at a near target?
Which pupil condition is characterized by slow and tonic near reaction when looking at a near target?
Signup and view all the answers
What type of pupil anomaly is indicated by small pupils that do not react to light but have normal near responses?
What type of pupil anomaly is indicated by small pupils that do not react to light but have normal near responses?
Signup and view all the answers
What indicates a need for additional assessment when pupils show inequality of size?
What indicates a need for additional assessment when pupils show inequality of size?
Signup and view all the answers
What is the main effect of damage to the sympathetic pathway in the eye?
What is the main effect of damage to the sympathetic pathway in the eye?
Signup and view all the answers
What is the distinguishing feature of Adie's tonic pupil regarding pilocarpine administration?
What is the distinguishing feature of Adie's tonic pupil regarding pilocarpine administration?
Signup and view all the answers
How would one describe the consensual response in Adie’s tonic pupil?
How would one describe the consensual response in Adie’s tonic pupil?
Signup and view all the answers
Study Notes
Binocular Vision - Lecture 9 - Pupils
- The lecture covers pupil size control pathways, testing methods, and abnormalities.
- Students will be able to identify afferent and efferent pathways controlling pupil size.
- Students will be able to describe parasympathetic and sympathetic nerve innervations.
- Students will be able to identify methods for testing pupil function.
- Students will be able to recognize common pupil function abnormalities.
Terms
- Afferent: Nerve carrying information towards the central nervous system.
- Efferent: Nerve carrying information away from the central nervous system.
- Sympathetic: "Fight and flight" response.
- Parasympathetic: "Rest and digest" response.
- Cholinergic receptors (muscarinic): Stimulated by acetylcholine.
- Adrenergic receptors (alpha 1): Stimulated by noradrenaline.
The Afferent Pathway
- Nerve carrying information towards the central nervous system.
- The pathway travels from the retina to the pretectal nuclei in the brain.
- Understanding the afferent pathway is essential for correlating damage effects to the pupils.
- Includes retinal ganglion cells, optic nerve, optic chiasm, optic tract, pretectal nucleus, Edinger-Westphal nucleus.
The Efferent Pathway
- Nerve carrying impulses away from the central nervous system toward the muscles controlling the pupil size.
- Includes:
- Sphincter muscle (parasympathetic): responsible for pupil constriction.
- Dilator muscle (sympathetic): responsible for pupil dilation.
Muscles Controlling Pupil Size
- The dilator and sphincter muscles work antagonistically to control pupil size.
- Dilator muscle: The main muscle responsible for pupil dilation in response to signals in the long ciliary nerve. It is innervated by adrenergic sympathetic fibers.
- Sphincter muscle: The main muscle responsible for pupil constriction in response to signals in the short ciliary nerve. It is innervated by cholinergic parasympathetic fibers.
Pupil Size in Different Light Conditions
- Dark lighting: Sphincter muscle relaxes, dilator muscle contracts, resulting in a larger pupil.
- Bright lighting: Sphincter muscle contracts, dilator muscle relaxes, leading to a smaller pupil.
Effects of Pharmaceutical Innovation
- Pharmaceuticals can either constrict or dilate pupils.
- Mydriasis (dilated pupil): Tropicamide, Cyclopentolate, Atropine, Phenylephrine.
- Miosis (constricted pupil): Pilocarpine.
Pupil Terminology
- Anisocoria: Inequality in pupil size.
- Miosis: Pupil constriction.
- Mydriasis: Pupil dilation.
Normal Pupils
- Typically round and equal in size.
- Diameter ranges from 3mm to 5mm in ambient light.
- Miotic pupils: Less than 3mm in diameter.
- Mydriatic pupils: Greater than 7mm in diameter.
Parasympathetic Pathway
- Runs from the Edinger-Westphal nucleus, through the oculomotor nerve (cranial nerve III), ciliary ganglion, short ciliary nerve, to the sphincter muscle in the iris.
Sympathetic Pathway
- Originates from the hypothalamus and travels to the superior cervical ganglion, subsequently to the dilator muscle in the iris via the long ciliary nerve.
Pupil Testing - Purpose
- To assess afferent and efferent neurological pathways responsible for pupil functions.
- Abnormalities can be life-threatening so careful evaluation is crucial.
Pupil Testing - Procedure
- Observation: Assess for anisocoria (unequal pupil sizes) in bright and dim light.
- Direct Response: Shine a light into one eye; the pupil should constrict.
- Consensual Response: Shine a light into one eye; the pupil in the other eye should also constrict.
- Swinging Flashlight Test: Rapidly move light between eyes to assess for pupillary escape/Marcus Gunn response.
- Near Reflex Test: Have the patient focus on a near object to assess accommodation and constriction.
Pupil Abnormalities
- Recording abnormalities using a standardized scale (e.g., 0 to 4+ for constriction).
Damage to the Afferent Pathway
- Key factors include light response in one eye versus the other, and differences in the direct and consensual responses.
- A lesion in the optic nerve or pathway can result in a reduced or absent direct and consensual response.
Damage to the Parasympathetic Pathway
- Results in a pupil that is consistently larger than its counterpart (common abnormalities include Adie's tonic pupil or damage to the 3rd nerve pathway with a fixed dilated pupil.)
- The inability of the pupil to respond to a light stimulus, particularly the consensual response, can be key in making the diagnosis.
Damage to the Sympathetic Pathway
- Pupil becomes smaller, known as Horner's syndrome.
- Common symptoms include ptosis, miosis, and anhydrosis, often with a possible etiology such as Pancoast tumor.
Argyll Robertson Pupil
- Small pupils that react poorly or not at all to light but respond normally to near (light-near dissociation)
- Associated with neurosyphilis and sometimes chronic diabetes or alcoholism.
Recording Abnormal Findings
- Use standardized terminology (e.g., PERRLA, RAPD) to objectively record pupil responses.
- Describe any abnormalities in pupil size or response to light and near situations.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This lecture focuses on the control pathways for pupil size, including afferent and efferent pathways, sympathetic, and parasympathetic innervations. Students will learn how to test pupil function and recognize common abnormalities. It gives a comprehensive understanding of the nervous system's influence on pupil responses.
