Axes of the eye Flashcards by Dela Luna, Desiree

24mm, Horizontal line from vertex of the cornea to posterior pole of the eye

Optic Axis / Y - axis / Antero- Sphero / Sagittal Axis

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22mm, Line passing through the center of rotation of the eye ball and at right angle to optic axis

Transverse axis / X axis / Naso-Temporal

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22mm, Superior-Inferior line passing through center of rotation

Vertical Axis / Z axis / Supero-Infero Axis

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Divides the eyeball

Planes of the eye

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Imaginary line where movement of the eye takes place

Axes of the eye

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torsional movement

optic axis

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vertical movement

transverse axis

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Horizontal movement

Vertical axis

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it is the act, condition or process of directing the eye toward the object of regard causing in a normal eye, the image of an object to be centered at the fovea

Fixation

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Image of the real pupil found at the cornea

entrance pupil

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Point towards which the observer directs his gaze

Object of regard

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Point Located 13.5 mm behind the cornea

Center of rotation

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Line drawn from the object of regard of rotation

Line of sight

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All oblique axes pass and it is where the movement of the eyes takes place

Center of rotation

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Line drawn from the object of regard to the fovea passing through nodal point

Visual Axis

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Line passes from the center of entrance pupil and passes through the center of curvature of the cornea

Pupillary axis

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An imaginary straight line passing through the midpoint of the cornea (anterior pole) and the midpoint of the retina (posterior pole)

Optic Axis

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Line perpendicular to the cornea and passing through the center of the entrance pupil of the eye

Pupillary axis

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Angle formed by the intersection of the pupillary axis and visual axis

Angle Kappa

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angle formed by the intersection of the pupillary axis and the line of sight

Angle lambda

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Angle formed by the visual ang optic axes at the nodal point

Angle alpha

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Angle formed by the intersection of the optic Axis and the line of sight at the center of rotation (formed behind)

Angle Gamma

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Line connecting the centers if rotation of both eyes

Base line

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Plane which includes both the object of regard and baseline

Plane of regard

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line in the primary position of the plane of regard which bisects the base line

Primary Sagittal line

Plane tangent to the chin and the two super-ciliary ridges

Face plane

Coordinate use of both eyes to produce single mental image

Binocular vision

Coordinated use of two eyes in order to produce a single mental impression

Single Binocular Vision

Eyes follow large objects

at 2 months

blending of sight to form single percept

Fusion

It is the state of simultaneous vision with two seeing eyes that occurs when an individual fixes his visual attention on an object of regard

Binocular Vision

Eyes are not associated with each other; act as two different organs

At birth

First sign of the development of fixation appears when the eyes follow light

In newborn

VA: 20/20

3 years Old

Fusional mechanism becomes fully developed

1-1 1/2 year old

VA: not greater than 5/200; normally hyperopic

At birth

Fixated at an object with 1-2 mins

At 6 months

Foveas are fully formed

at 3 months

VA: 20/70

1 year old

VA: 20/20

3 yeard old

Eyes are expected to be straight

at 6 months

Accommodation develops with sharpening visual acuity

3 years old

Foveas are fully formed, they hold objects

at 3 months

Proper coordination of eyes and brain

Neuroplasticity

superior visual field angle

60 degrees

nasal visual field angle

60 degrees

Inferior visual angle

70-75 degrees

Temporal Visual field angle

100-110 degrees

Holds that if the two images of an object fall upon identical points in the retinas, the object is seen as one, but of the two images falls upon unidentical or disparate points, the object is seen as two

Doctrine of Corresponding Points

Corresponding retinal points / homonymous points / identical points

Normal Retinal Correspondence

A condition in which the two foveas have different visual direction

Abnormal Retinal Correspondence

movement of one eye inwards

Adduction

Retinal correspondence is abnormal when the fovea if one has a common visual direction with an extra foveal area in the other eye

Abnormal retinal correspondence

Movement of one eye only

Duction

movement of one eye outwards

abduction

movement of one eye upwards

supraduction

movement of one eye downwards

infraduction

movement of the vertical corneal meridian of one eye outward

Excycloduction

movement of the vertical corneal meridian of one eye inward

incycloduction

synchronous and symmetric movement of both eyes in the same direction

version

both eyes to the right

dextroversion

both eyes to the left

levoversion

both eyes looking upward

supraversion/anaversion/sumsum version

both eyes looking downward

infraversion/cataversion/deorsumversion

both eyes to the right and up

Dextrosupraversion

both eyes to the right and down

dextroinfraversion

both eyes to the left and up

levosupraversion

both eyes to the left and down

levoinfraversion

synchronous and symmetric movement of both eyes in the opposite direction

vergence

movement of both eyes inward

convergence

movement of both eyes outward

divergence

right eye turns up and left eye turns down

positive vertical divergence

right eye turns down left up turns up

negative vertical divergence

vertical meridians of both eyes rotate inward

incyclovergence/conclination

vertical meridians of both eyes inward

excyclovergence/declination

position when the eyes assume when the head erect, point straight upon ahead on the horizon is fixed upon

primary position

Position in which the eyes assume when the lateral or vertical movements are involved.

Secondary Position

Position in which the eyes assume when it moves in direction which is a combination of both lateral and vertical movements

Tertiary Position

Tracking mechanism of the eye

Extraocular muscle

-Medial Rectus -Superior Rectus -Laterial Rectus -Inferior Rectus

Recti muscles

-Superior Oblique -Inferior Oblique

Obliquee muscles

All extra muscles are originate from the annulus of zin

Extraocular muscle

All extra ocular muscles are innervated by

CN#3 - Oculomotor Nerve

Superior oblique is innervated by

Trochlear Nerve

Lateral Rectus is innervated by

CN#6 - ABDUCENS NERVE

Medial rectus is innervated by

CN#3 Oculomotor Nerve

Superior Rectus, Inferior Oblique is innervated by

CN#3 Oculomotor nerve

Points of connections of all recti muscles

Spiral of Tillaux

Cross diagram that shows which muscle move when the eye moves to a given direction

Benzene ring

primary muscle, main muscle that moves an eye in a given direction

Agonist

Helping muscle, Muscle that acts in concert with the agonist to produce a given moment

Synergist

Opposing muscle, Muscle that opposes the action if the agonist

Antagonist

agonist muscle of both eyes

Yoke muscle

a pair of muscle, one in each eye which move noth eyes into specific direction

Yoke muscle

Phenomenon in which the images are not formed in the corresponding elements

Diplopia

Corresponding muscle of the two eyes that affect movement of both Eyes into specific gaze

Yoke muscle

States that when a nervous impulse is sent to muscle causing it to contract, an equal impulse goes to the contralateral synergist(yoke muscle) in order to maintain parallelism of the visual axes

herings law of equal innervation

states that when a muscle contracts, its direct antagonist relaxes to an equal extent, allowing movement to take place monocular/one eye

Sherringtons Law of reciprocal innervation

line of primary position of the plane of regard which bisects the baseline

primary sagittal plane

lie the optic axis and transverse axis

Horizontal plane

Lie the optic axis and vertical axis

Medial Plane / Sagittal

Lie the transverse axis and Vertical axis

Equatorial Plane

Divides the eyeball to right and left

Medial Axis/Sagittal

divides the eyeball to anterior and posterior halves

Equatorial Plane / Frontal

Divides the eyeball from up and down

Horizontal Axis