أسئلة المحاضرة الثامنة رمد (قبل التعديل)
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Questions and Answers

What is the significance of corresponding retinal points in the perception of images?

Corresponding retinal points allow for the fusion of similar images, enabling clear vision.

Define simultaneous perception in the context of visual perception.

Simultaneous perception refers to the ability to perceive images from both eyes at the same time, even if the images are dissimilar.

Explain the difference between comitant and non-comitant deviation of visual axes.

Comitant deviation exhibits a consistent angle regardless of gaze direction, while non-comitant deviation varies with the direction of gaze.

What conditions lead to a lack of fusion when images are unequal?

<p>Conditions like aniseikonia, blurred images due to ametropia, or unclear images caused by cataracts prevent fusion.</p> Signup and view all the answers

Identify the characteristics of paralytic deviation in visual perception.

<p>Paralytic deviation is characterized by a limitation of movement and a variance in the angle of deviation with gaze direction.</p> Signup and view all the answers

Describe the condition of esodeviation and its potential predisposing factors.

<p>Esodeviation involves a small interpupillary distance and is often noted in high myopia.</p> Signup and view all the answers

What symptoms can indicate a paralytic deviation of the visual axes?

<p>Symptoms may include limited movement, eye deviation, binocular diplopia, and abnormal head posture.</p> Signup and view all the answers

What is mentioned about the role of the synoptophore in visual perception?

<p>The synoptophore is utilized to assess and improve binocular vision by aligning the visual axes.</p> Signup and view all the answers

What indicates the presence of a paralytic squint?

<p>Binocular diplopia, especially in the field of action of the paralyzed muscle, indicates a paralytic squint.</p> Signup and view all the answers

How does Hering's Law relate to ocular deviation in paralytic squint?

<p>Hering's Law states that equal amounts of neural stimulus are required for both eyes; thus, a higher stimulus for the paretic eye leads to greater ocular deviation.</p> Signup and view all the answers

What type of head posture may a patient adopt to avoid diplopia in paralytic squint?

<p>The patient may adopt a face turn, head tilt, or change chin position to minimize eye movement and avoid diplopia.</p> Signup and view all the answers

Differentiate between crossed and uncrossed binocular diplopia in strabismus.

<p>Uncrossed diplopia occurs in esotropia, while crossed diplopia is associated with exotropia.</p> Signup and view all the answers

What psychological effects can result from binocular diplopia in paralytic squint?

<p>Nausea, vertigo, and uncertain gait may arise as psychological effects of binocular diplopia.</p> Signup and view all the answers

What is the significance of iridodialysis in terms of visual functionality?

<p>Iridodialysis can lead to unoculor diplopia, significantly affecting visual alignment and focus.</p> Signup and view all the answers

Explain how a patient with a paralytic squint might respond when asked to point at an object in the field of action of a paretic muscle.

<p>The patient will likely point behind the object, demonstrating false projection according to the nervous energy exerted.</p> Signup and view all the answers

What ocular condition may develop as a result of significant aniseokonia?

<p>Significant aniseokonia can lead to squint and binocular diplopia.</p> Signup and view all the answers

What are the three cranial nerves involved in controlling eye movement?

<p>Oculomotor (III), Trochlear (IV), and Abducent (VI).</p> Signup and view all the answers

Describe the movement of the eye around the vertical axis.

<p>The eye moves horizontally through adduction and abduction.</p> Signup and view all the answers

What is the primary action of the superior rectus muscle?

<p>The superior rectus is the main elevator of the abducted eye.</p> Signup and view all the answers

What role does the lateral rectus muscle play in eye movement?

<p>The lateral rectus muscle is responsible for abduction of the eye.</p> Signup and view all the answers

Identify the origin of the superior oblique muscle.

<p>The superior oblique muscle originates at the apex of the orbit, rolling around the trochlea.</p> Signup and view all the answers

What types of movements occur around the horizontal axis of the eye?

<p>The eye moves vertically through elevation and depression.</p> Signup and view all the answers

Explain the action of the inferior oblique muscle.

<p>The inferior oblique muscle primarily performs elevation and extorsion.</p> Signup and view all the answers

What is the insertion point of the inferior rectus muscle?

<p>The inferior rectus muscle inserts at the anterior inferior sclera.</p> Signup and view all the answers

What is the primary action of the inferior rectus muscle?

<p>The primary action of the inferior rectus muscle is to depress the abducted eye.</p> Signup and view all the answers

Which muscle is the main elevator of an adducted eye?

<p>The inferior oblique muscle is the main elevator of an adducted eye.</p> Signup and view all the answers

Which extraocular muscle is primarily responsible for abduction of the eye?

<p>The lateral rectus muscle (LR) is primarily responsible for abduction of the eye.</p> Signup and view all the answers

In which position do both superior and inferior oblique muscles assist in eye depression?

<p>Both superior and inferior oblique muscles assist in depression in the primary position.</p> Signup and view all the answers

What muscles assist in the elevation of the eye when it is in the abducted position?

<p>In the abducted position, the superior rectus muscle assists in eye elevation.</p> Signup and view all the answers

Describe the role of the medial rectus muscle in adduction.

<p>The medial rectus muscle is primarily responsible for adduction of the eye.</p> Signup and view all the answers

Which muscles primarily contribute to the depression of the eye in the adducted position?

<p>In the adducted position, the superior oblique muscle is the primary depressor.</p> Signup and view all the answers

What defines the 'prime position' of gaze for both eyes?

<p>The prime position of gaze is achieved by the coordinated tone of all extraocular muscles.</p> Signup and view all the answers

What muscles are responsible for dextroversion?

<p>The lateral rectus muscle of the right eye and the medial rectus muscle of the left eye contract for dextroversion.</p> Signup and view all the answers

How is levoversion achieved?

<p>Levoversion is achieved by the contraction of the medial rectus muscle of the right eye and the lateral rectus muscle of the left eye.</p> Signup and view all the answers

What eye muscles contract during the elevation of both eyes?

<p>The superior rectus and inferior oblique muscles of both eyes contract during elevation.</p> Signup and view all the answers

What is the primary function of the medial rectus muscles in convergence?

<p>The medial rectus muscles of both eyes contract to achieve convergence.</p> Signup and view all the answers

Define the term 'near point of convergence'.

<p>The near point of convergence is the closest point at which the eyes can converge, normally ranging from 8-10 centimeters.</p> Signup and view all the answers

What is the AC/A ratio and its significance in the near reflex?

<p>The AC/A ratio is a constant that reflects the amount of accommodative convergence associated with a fixed amount of accommodation.</p> Signup and view all the answers

At what age does the coordinated use of two eyes to produce a single visual impression typically start to develop?

<p>The coordinated use of two eyes starts to develop at 3-6 months of age.</p> Signup and view all the answers

How can divergence be defined in relation to eye movement?

<p>Divergence is achieved by the contraction of the lateral rectus muscles of both eyes.</p> Signup and view all the answers

What is anomalous retinal correspondence and how does it relate to sensory anomalies?

<p>Anomalous retinal correspondence occurs when the visual system adapts to misalignment by developing an abnormal interpretation of visual inputs. It is often associated with sensory anomalies like amblyopia and eccentric fixation.</p> Signup and view all the answers

What clinical features are typically observed in abducens palsy?

<p>In abducens palsy, limited abduction of the affected eye and esotropia are typically observed. Patients may also experience uncrossed diplopia and an abnormal head posture turning towards the side of the affected eye.</p> Signup and view all the answers

Describe the treatment options available for accommodative esotropia.

<p>Treatment for accommodative esotropia includes full correction of hypermetropia and the use of reading glasses or bifocals for those with a high AC/A ratio. Additionally, treatment of amblyopia may be necessary.</p> Signup and view all the answers

What characterizes congenital esotropia and what is its treatment?

<p>Congenital esotropia is characterized by a stable, large angle of deviation often seen within 6 months and is frequently hereditary. Treatment involves surgical alignment after correcting any amblyopia and refractive errors.</p> Signup and view all the answers

What is cross fixation and in which condition is it commonly seen?

<p>Cross fixation is when a patient uses one eye to view objects in the field of the opposite eye while suppressing the other eye. This is commonly seen in congenital esotropia.</p> Signup and view all the answers

List two potential causes of sensory anomalies.

<p>Potential causes of sensory anomalies include unilateral cataract and anisometropia. Other causes can be optic atrophy and corneal opacities.</p> Signup and view all the answers

What are the typical symptoms experienced by patients with trochlear palsy?

<p>Patients with trochlear palsy typically experience vertical diplopia and hypertropia of the adducted eye. They often exhibit head tilt and facial turn towards the normal side.</p> Signup and view all the answers

Explain the term 'false projection' as it applies to eye muscle palsies.

<p>False projection refers to a misperception of visual orientation due to muscle imbalances, commonly seen in both abducens and trochlear palsies. Patients may struggle to perceive where objects are located in space.</p> Signup and view all the answers

What muscles are contracted for upward movement of both eyes?

<p>The superior rectus and inferior oblique muscles are contracted.</p> Signup and view all the answers

How is convergence measured in terms of meter angle?

<p>Each one-meter angle is equivalent to about 4 prism diopters.</p> Signup and view all the answers

What is the typical range for the near point of convergence?

<p>It normally ranges from 8 to 10 centimeters.</p> Signup and view all the answers

What defines the role of the lateral rectus muscle during eye movements?

<p>It is primarily responsible for the abduction of the eye.</p> Signup and view all the answers

At what age is full maturation of binocular vision typically achieved?

<p>Full maturation is achieved by 9 years of age.</p> Signup and view all the answers

What is the AC/A ratio, and why is it significant?

<p>The AC/A ratio is constant; it represents the amount of accommodation associated with accommodative convergence.</p> Signup and view all the answers

Describe the coordinated use of both eyes in producing a single visual impression.

<p>This coordination typically begins developing at 3-6 months of age.</p> Signup and view all the answers

What characterizes dextroversion in eye movement?

<p>Dextroversion is achieved by the contraction of the lateral rectus muscle of the right eye and the medial rectus muscle of the left eye.</p> Signup and view all the answers

What occurs to objects that are not aligned with corresponding retinal points?

<p>They are seen simultaneously but not fused.</p> Signup and view all the answers

How is stereopsis achieved in the context of retinal images?

<p>By fusing slightly discrete retinal images falling onto corresponding retinal points.</p> Signup and view all the answers

In the case of non-comitant deviations, what is one primary cause related to muscle issues?

<p>Muscle paralysis due to orbital disease or trauma.</p> Signup and view all the answers

What might indicate a case of esodeviation in a patient?

<p>Features such as a small inter-pupillary distance and high myopia.</p> Signup and view all the answers

What are the movements limited in a patient with paralytic squint?

<p>Limited abduction and adduction of the affected eye.</p> Signup and view all the answers

Explain the clinical appearance of a patient with false projection in the context of eye muscle palsies.

<p>They may display misalignment of visual axes, leading to incorrect perception of object locations.</p> Signup and view all the answers

What factors predispose individuals to non-comitant visual axis deviations?

<p>Uncontrolled diabetes mellitus, hypertension, and atherosclerosis.</p> Signup and view all the answers

What is the primary symptom that may manifest with binocular diplopia?

<p>The perception of double vision.</p> Signup and view all the answers

Which extraocular muscle is primarily responsible for depression of an adducted eye?

<p>The Superior Oblique muscle is the main depressor of an adducted eye.</p> Signup and view all the answers

What is the primary action of the Lateral Rectus muscle?

<p>The primary action of the Lateral Rectus muscle is abduction.</p> Signup and view all the answers

In the primary position, which muscles assist in the elevation of the eye?

<p>The Superior Rectus and Inferior Oblique muscles assist in elevation in the primary position.</p> Signup and view all the answers

What role do the Superior Rectus and Inferior Rectus muscles play in eye depression during abduction?

<p>In abduction, the Inferior Rectus muscle is the main depressor, while the Superior Rectus also assists.</p> Signup and view all the answers

Which muscle is predominantly responsible for elevation in an abducted eye?

<p>The Superior Rectus muscle is the main elevator in an abducted eye.</p> Signup and view all the answers

How are the movements in dextroversion achieved?

<p>Dextroversion is achieved through coordinated contraction of extraocular muscles, particularly the right lateral rectus and left medial rectus.</p> Signup and view all the answers

What defines the 'prime position' of gaze for both eyes?

<p>The 'prime position' of gaze is defined as looking straight ahead with both eyes using the tone of all extraocular muscles.</p> Signup and view all the answers

Which muscles are involved in intorsion of the eye?

<p>The Superior Rectus and Inferior Rectus muscles are responsible for intorsion.</p> Signup and view all the answers

What cranial nerve controls the lateral rectus muscle responsible for eye abduction?

<p>The Abducent nerve (VI) controls the lateral rectus muscle.</p> Signup and view all the answers

Which eye movement occurs around the horizontal axis and which extraocular muscles are primarily involved?

<p>Elevation and depression occur around the horizontal axis, primarily involving the superior and inferior rectus muscles.</p> Signup and view all the answers

Identify the primary action of the inferior oblique muscle.

<p>The inferior oblique muscle primarily performs elevation and extorsion of the eye.</p> Signup and view all the answers

What is the origin of the superior oblique muscle, and what is its main function?

<p>The superior oblique muscle originates at the apex of the orbit, and its main function is to facilitate intorsion and abduction.</p> Signup and view all the answers

Which movements are classified under torsional movements performed by the eye?

<p>Torsional movements include intorsion and extorsion.</p> Signup and view all the answers

Explain the difference between the actions of the superior and inferior rectus muscles.

<p>The superior rectus muscle is responsible for elevating the eye, while the inferior rectus muscle is responsible for depressing the eye.</p> Signup and view all the answers

What are the axes around which eye movements occur, and how are they classified?

<p>Eye movements occur around three axes: the vertical axis (adduction and abduction), horizontal axis (elevation and depression), and antero-posterior axis (intorsion and extorsion).</p> Signup and view all the answers

Identify the muscles responsible for adduction of the eye.

<p>The medial rectus and the superior and inferior rectus muscles are responsible for adduction.</p> Signup and view all the answers

What does limited depression of an abducted eye suggest in terms of ocular deviation?

<p>It suggests a possible palsy affecting the muscle responsible for depression.</p> Signup and view all the answers

How does the amount of neural stimulus relate to the angle of deviation in a paralytic squint?

<p>A larger neural stimulus is required for the paretic eye, resulting in a larger angle of deviation.</p> Signup and view all the answers

What type of diplopia is primarily associated with a paralytic squint?

<p>Binocular diplopia is primarily associated with a paralytic squint.</p> Signup and view all the answers

What is the significance of facial posture in patients with diplopia?

<p>Patients may adopt facial postures to minimize diplopia and reduce the need for eye movement.</p> Signup and view all the answers

Describe the visual perception of a patient with a paralytic squint when asked to point at an object.

<p>The patient will typically point behind the object due to false projection.</p> Signup and view all the answers

In the context of esotropia and exotropia, how does binocular diplopia differ?

<p>Binocular diplopia is uncrossed in esotropia and crossed in exotropia.</p> Signup and view all the answers

What ocular condition can result from significant aniseokonia?

<p>Subluxated lens can result from significant aniseokonia.</p> Signup and view all the answers

How does head posture aid in compensating for ocular disorders?

<p>Head posture adjusts to minimize eye movement and mitigate diplopia effects.</p> Signup and view all the answers

What visual condition is characterized by esotropia and limited abduction of the eye?

<p>Abducens palsy.</p> Signup and view all the answers

In terms of sensory anomalies, what are the possible causes for unilateral visual impairments leading to amblyopia?

<p>Anisometropia, unilateral cataract, optic atrophy, and injuries.</p> Signup and view all the answers

What defines the treatment approach for accommodative esotropia?

<p>Full correction of hypermetropia and potentially reading glasses or bifocals if there is a high AC/A ratio.</p> Signup and view all the answers

How does cross fixation manifest in patients with congenital esotropia?

<p>Patients use their right eye for the left field and vice versa, suppressing the other eye.</p> Signup and view all the answers

What clinical symptom might suggest trochlear palsy in a patient?

<p>Vertical diplopia and abnormal head posture.</p> Signup and view all the answers

What is the primary treatment for congenital esotropia after addressing amblyopia?

<p>Surgical alignment involving recession of both medial recti.</p> Signup and view all the answers

What visual symptom is characterized by the misrepresentation of the visual field in patients with certain ocular disorders?

<p>False projection.</p> Signup and view all the answers

What role does high hypermetropia play in developing ocular conditions?

<p>It can lead to excessive accommodation and contribute to accommodative esotropia.</p> Signup and view all the answers

Which extraocular muscle is primarily responsible for the depression of the adducted eye?

<p>Superior Oblique</p> Signup and view all the answers

Which muscles assist in the elevation of the eye while it is in the adducted position?

<p>Superior Rectus and Inferior Oblique</p> Signup and view all the answers

What is the main action of the lateral rectus muscle?

<p>Abduction of the eye</p> Signup and view all the answers

In which position do both superior and inferior oblique muscles assist in eye depression?

<p>Adducted position only</p> Signup and view all the answers

What defines the 'prime position' of gaze for both eyes?

<p>Both eyes looking straight ahead</p> Signup and view all the answers

Which extraocular muscle assists in both intorsion and elevation of the eye?

<p>Superior Oblique</p> Signup and view all the answers

Which muscle primarily contributes to adduction of the eye?

<p>Medial Rectus</p> Signup and view all the answers

What action does the superior rectus muscle predominantly perform in the abducted eye?

<p>Elevation</p> Signup and view all the answers

What typically results from limited depression of the adducted eye?

<p>Ocular deviation</p> Signup and view all the answers

In a paralytic squint, which type of diplopia occurs?

<p>Binocular diplopia</p> Signup and view all the answers

What determines the larger angle of deviation in a secondary squint?

<p>Need for high neural stimulus</p> Signup and view all the answers

What kind of projection occurs when the normal eye is closed and the patient is asked to point at an object?

<p>False projection</p> Signup and view all the answers

Which head posture compensates for horizontal movement weakness in the eye?

<p>Face turn</p> Signup and view all the answers

What symptom can indicate the presence of binocular diplopia?

<p>Nausea</p> Signup and view all the answers

What type of diplopia is associated with esotropia?

<p>Uncrossed diplopia</p> Signup and view all the answers

What is a potential consequence of significant aniseokonia?

<p>Abnormal head posture</p> Signup and view all the answers

What muscles are involved when looking upward and to the right?

<p>Superior rectus of the right eye and inferior oblique of the right eye</p> Signup and view all the answers

What occurs during the movement of both eyes together in elevation?

<p>Contraction of superior rectus and inferior oblique muscles</p> Signup and view all the answers

How is convergence normally associated with the near reflex?

<p>With miosis and accommodation</p> Signup and view all the answers

What defines the AC/A ratio in relation to accommodation?

<p>The constant amount of accommodative convergence with accommodation</p> Signup and view all the answers

At what age does the coordinated use of both eyes to produce a single visual impression typically begin?

<p>3-6 months</p> Signup and view all the answers

What is the nearest point on which the eye can converge and what is its typical range?

<p>8-10 centimeters</p> Signup and view all the answers

Which muscles are primarily responsible for achieving depression of both eyes together?

<p>Inferior rectus and superior oblique</p> Signup and view all the answers

What type of eye movement is achieved through the contraction of the lateral rectus muscles of both eyes?

<p>Divergence</p> Signup and view all the answers

What is the likely cause of esotropia in the context of accommodative anomalies?

<p>High hypermetropia</p> Signup and view all the answers

Which symptom is specifically associated with abducens palsy?

<p>Esotropia</p> Signup and view all the answers

What type of diplopia is typically observed in trochlear palsy?

<p>Vertical diplopia</p> Signup and view all the answers

Which of the following is NOT a treatment option for accommodative esotropia?

<p>Surgical alignment of the eyes</p> Signup and view all the answers

Which cranial nerve is responsible for innervating the lateral rectus muscle?

<p>Abducent Nerve (VI)</p> Signup and view all the answers

Which condition is characterized by a patient suppressing one eye while using the other to fixate on objects in the opposite field?

<p>Cross fixation</p> Signup and view all the answers

The superior rectus muscle is primarily responsible for which of the following actions?

<p>Elevation of an abducted eye</p> Signup and view all the answers

Which sensory anomaly can result from a unilateral cataract?

<p>Amblyopia</p> Signup and view all the answers

Which of the following muscles performs intorsion of the eye?

<p>Superior Oblique</p> Signup and view all the answers

What is a common sign of congenital esotropia in infants?

<p>Stable angle deviation</p> Signup and view all the answers

Which of the following conditions is characterized by false orientation?

<p>Trochlear palsy</p> Signup and view all the answers

What movement occurs around the horizontal axis of the eye?

<p>Elevation and Depression</p> Signup and view all the answers

The primary nerve supply for the inferior oblique muscle comes from which cranial nerve?

<p>Oculomotor Nerve (III)</p> Signup and view all the answers

Which axis of eye movement allows for torsional movements?

<p>Antero-Posterior Axis</p> Signup and view all the answers

Which muscle primarily assists in the adduction of the eye?

<p>Medial Rectus</p> Signup and view all the answers

What is the origin point for the superior oblique muscle?

<p>Between superior and medial rectus</p> Signup and view all the answers

What results when images on corresponding retinal points are similar in size, sharpness, and brightness?

<p>The images are fused into a single perception.</p> Signup and view all the answers

What characterized non-comitant deviations of visual axes?

<p>The angle of deviation changes with the direction of gaze.</p> Signup and view all the answers

Which ocular condition is most likely to result from unequal images like aniseikonia?

<p>Binocular diplopia</p> Signup and view all the answers

Which of the following is a symptom associated with paralytic deviation?

<p>Abnormal head posture</p> Signup and view all the answers

What type of eye deviation is likely found in individuals with high hypermetropia?

<p>Exodeviation</p> Signup and view all the answers

What describes a situation where images are perceived but cannot be fused due to clarity issues?

<p>Ametropia</p> Signup and view all the answers

What is the main cause of paralytic squint as indicated in the clinical picture?

<p>Muscle paralysis from orbital disease</p> Signup and view all the answers

Which condition is most likely to result from a high inter-pupillary distance (IPD)?

<p>Exodeviation</p> Signup and view all the answers

What axis allows for the eye to perform torsional movements such as intorsion and extorsion?

<p>Antero-posterior axis</p> Signup and view all the answers

Which cranial nerve is responsible for innervating the superior oblique muscle?

<p>Trochlear nerve</p> Signup and view all the answers

Which muscle is primarily responsible for the abduction movement of the eye?

<p>Lateral rectus</p> Signup and view all the answers

What is the primary action of the inferior oblique muscle?

<p>Elevation</p> Signup and view all the answers

Which extraocular muscle primarily contributes to the depression of the eye when the eye is adducted?

<p>Inferior rectus</p> Signup and view all the answers

What is the origin point for the lateral rectus muscle?

<p>Common tendinous ring</p> Signup and view all the answers

Which axis allows the eye to perform horizontal movements such as adduction and abduction?

<p>Vertical axis</p> Signup and view all the answers

What major function does the superior rectus muscle serve when the eye is abducted?

<p>Elevation</p> Signup and view all the answers

What occurs when images fall onto corresponding retinal points and are similar in size, sharpness, and brightness?

<p>The images are fused</p> Signup and view all the answers

Which type of visual axis deviation is characterized by the angle of deviation differing with the direction of gaze?

<p>Non-comitant deviation</p> Signup and view all the answers

Which muscle is primarily responsible for depression of the eye in the adducted position?

<p>Superior Oblique</p> Signup and view all the answers

What is the main function of the inferior oblique muscle?

<p>Elevation of adducted eye</p> Signup and view all the answers

In which condition does no fusion occur due to the presence of unequal images?

<p>Aniseikonia</p> Signup and view all the answers

In which position do both superior and inferior oblique muscles assist in eye elevation?

<p>Primary position</p> Signup and view all the answers

Which muscle limitation is associated with limited adduction?

<p>Medial rectus</p> Signup and view all the answers

What is the primary action of the lateral rectus muscle?

<p>Abduction of the eye</p> Signup and view all the answers

What type of eye condition may develop as a result of blurred images or unequal images?

<p>Aniseikonia</p> Signup and view all the answers

Which muscles assist in the elevation of the eye when it is in the adducted position?

<p>Inferior Oblique and Superior Rectus</p> Signup and view all the answers

Which symptom is NOT typically associated with paralytic deviation of the visual axes?

<p>Normal eye movement</p> Signup and view all the answers

What is the main predisposing factor for paralytic deviation related to eye muscles?

<p>Uncontrolled diabetes</p> Signup and view all the answers

Which extraocular muscle is engaged in intorsion of the eye?

<p>Superior Oblique</p> Signup and view all the answers

Which muscle is primarily associated with adduction of the eye?

<p>Medial Rectus</p> Signup and view all the answers

In terms of deviance type, which condition includes limitations on movement due to muscle paralysis?

<p>Paralytic deviation</p> Signup and view all the answers

What is the role of the lateral rectus muscle in relation to the cranial nerves?

<p>Supplied by the Abducens Nerve (6th)</p> Signup and view all the answers

What muscle contraction is primarily responsible for achieving levoversion?

<p>Contraction of the MR muscle of the left eye</p> Signup and view all the answers

Which movement is associated with the contraction of the IR and SO muscles of both eyes?

<p>Depression</p> Signup and view all the answers

What best describes the action of accommodative convergence?

<p>It is measured in prism diopters.</p> Signup and view all the answers

What is the normal range for the near point of convergence?

<p>8-10 centimeters</p> Signup and view all the answers

At what age is full maturation of binocular vision typically achieved?

<p>9 years</p> Signup and view all the answers

Which will happen during the meter angle measurement of convergence?

<p>It converts one meter angle to about 4 prism diopters.</p> Signup and view all the answers

Which of the following best describes the relationship between complementary and oppositional muscle actions in eye movement?

<p>Complementary muscles pull in the same direction, while oppositional muscles pull in opposite directions.</p> Signup and view all the answers

What role does the lateral rectus muscle primarily perform during eye movement?

<p>Abduction of the adducted eye</p> Signup and view all the answers

What is the primary symptom experienced by a patient with binocular diplopia in paralytic squint?

<p>Seeing double vision with both eyes in the field of action of the paralyzed muscle</p> Signup and view all the answers

Which of the following best describes the head posture adopted to minimize diplopia in a patient with a paralytic squint?

<p>Face turned away from the paretic muscle's field of action</p> Signup and view all the answers

What condition is characterized by a larger secondary angle of deviation compared to the primary angle in ocular deviation?

<p>Paralytic squint</p> Signup and view all the answers

Which phenomenon occurs when a patient points behind an object while attempting to fixate due to false projection?

<p>Mislocalization</p> Signup and view all the answers

What type of binocular diplopia would be expected in a patient with esotropia?

<p>Crossed diplopia</p> Signup and view all the answers

Which symptom is NOT commonly associated with binocular diplopia in cases of paralytic squint?

<p>Photophobia</p> Signup and view all the answers

In the context of ocular deviation, what does Hering’s Law imply?

<p>Equal neural stimulus to both eyes leads to more deviation in the paretic eye</p> Signup and view all the answers

What ocular condition may result from an abnormal head posture attempting to compensate for diplopia?

<p>Significant aniseokonia</p> Signup and view all the answers

What is a common symptom associated with abducens palsy?

<p>Uncrossed diplopia</p> Signup and view all the answers

Which condition is typically characterized by an alternating, large, and stable angle of deviation?

<p>Congenital esotropia</p> Signup and view all the answers

What treatment approach is generally recommended for accommodative esotropia with high AC/A ratio?

<p>Full correction of hypermetropia</p> Signup and view all the answers

Which symptom is NOT typically associated with trochlear palsy?

<p>Face turn to the same side</p> Signup and view all the answers

In the context of sensory anomalies, what is a cause that may lead to the need for surgical treatment after correction?

<p>Anisometropia</p> Signup and view all the answers

What visual condition is characterized by patients using one eye to view objects in one field while suppressing the other eye?

<p>Cross fixation</p> Signup and view all the answers

What typical symptom would NOT be found in patients suffering from sensory anomalies?

<p>Dual simultaneous aiming</p> Signup and view all the answers

What is a primary characteristic of sensory anomalies that leads to visual disturbances?

<p>Anisometropia</p> Signup and view all the answers

Study Notes

Extraocular Muscles

  • Eye movement is a complex function controlled by three cranial nerves (oculomotor, trochlear, and abducent)
  • The eye can rotate around three axes: vertical, horizontal, and antero-posterior
  • Vertical axis: movement horizontally (adduction and abduction)
  • Horizontal axis: movement vertically (elevation and depression)
  • Antero-posterior axis: torsional movements (intorsion and extorsion)

Extraocular Muscle Actions

  • Superior Rectus: main elevator of abducted eye
  • Inferior Rectus: main depressor of abducted eye
  • Inferior Oblique: main elevator of adducted eye
  • Superior Oblique: main depressor of adducted eye
  • Lateral Rectus: abduction
  • Medial Rectus: adduction

Summary of Eye Muscle Innervation

  • All extraocular muscles (EOM) originate from the apex of the orbit
  • All EOM insert into the anterior sclera
  • All EOM are supplied by Oculomotor nerve (3rd) except the Lateral Rectus (6th) and Superior oblique (4th)

Types of Squint (Deviation/Strabismus)

  • Comitant: Same angle of deviation in all directions of gaze.

    • Mechanical (muscle development, fascia issues, etc)
    • Motor (convergence issues, etc)
    • Sensory (fusion issues, etc)
    • Heterophoria: tendency to deviate, easily corrected by fusion
    • Esophoria: eye turns inward
    • Exophoria: eye turns outward
    • Hyperphoria: upward deviation
    • Cyclotropia: torsional deviation

  • Non-comitant/Paralytic: Angle of deviation differs with direction of gaze.

    • Caused by muscle paralysis or paresis (trauma, infection, etc)

Binocular Eye Movements

  • Version: achieved by separate movements of both eyes
  • Duction: coordinated eye movements, measured using the meter angle

Binocular Vision

  • The development of coordinated binocular vision is a crucial developmental process.
  • It starts around 3-6 months old.
  • Full maturation of binocular vision is achieved around 9 years old.
  • Grades of binocular vision:
    • Grade 1 (Simultaneous Perception): Perception of images from both eyes even if different.
    • Grade 2 (Fusion): Fusion of identical images from both eyes. Requires similar size, sharpness, and clarity.
    • Grade 3 (Stereopsis): Perception of depth based on slightly different images from each eye.
  • The development of binocular vision is based on normal visual development, often affected by various factors

Tests for Squint

  • Cover Test: The cover test can be used with prisms to detect deviations of the eyes.
  • Maddox Rod Test: this tests is used to determine heterophoria (a tendency to deviate) at a distance. Patients looking through the rod will see a red line and nothing if the other eye isn't covered.
  • Maddox Wing Test: this tests for heterophoria at a closer distance (33 cm). Using a diaphragm, a red horizontal scale and a white vertical scale will be seen by one eye, and the other eye will see arrows, allowing to detect for tendencies in deviating.
  • Worth's Test: this test is used to measure the presence or absence of suppressive tendencies, through using red and green glasses.

Treatment of Paralytic Squint

  • Early detection is key in improving the results of treatment
  • Medical workup (vascular lesions), neurosurgical evaluation (compressive lesions).
  • Prisms are used to relieve diplopia.
  • The power/degree of the prism is based on the primary angle (the angle of deviation where the eye starts and is initially focused).
  • Surgical intervention is considered if there is no significant improvement after 6 months from diagnosis. Procedure would be based on the affected muscles and may involve resection (removing excess muscle tissue) or weakening (recession) of the antagonist muscle, muscle transposition, etc.. The primary goal of treatment is correction plus elimination of amblyopia and correction of any refractive errors.

Heterotropia (Types)

  • Types of heterotropia defined based on: Deviation of the eyes, fusion status/fixation, and role or lack of role of accommodation
  • Exotropia: Outward deviation
  • Esotropia: Inward deviation
  • Hypertropia: Upward deviation
  • Hypotropia: Downward deviation
  • Cyclotropia: Torsional deviation
  • Intermittent: Deviation is present only sometimes
  • Constant: Deviation is present all the time

Worth's 4-Dot Test

  • Patients wear red-green filters
  • Normal patients see 4 dots
  • Esophoria: 5 dots, 3 green dots on same side of green filter, 2 red dots on same side of red filter
  • Exophoria: 5 dots, 3 green dots on opposite side of red filter, 2 red dots on opposite side of green filter

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