JLH Lab The Eye

Extrinsic eye muscles

1.Lateral rectus muscle 2.Medial rectus muscle 3.Superior rectus muscle 4.Inferior rectus muscle 5.Superior oblique muscle 6.Inferior oblique muscle

Visual Acuity Test

A visual acuity test is an eye exam that checks how well you see the details of a letter or symbol from a specific distance.

Lens of eye

By changing its shape, the lens changes the focal distance of the eye. In other words, it focuses the light rays that pass through it

Action and CN of Superior oblique

Depresses eye & turns it laterally CN IV (trochlear)

Action and CN of Inferior rectus

Depresses eye & turns it medially CN III (Oculomotor)

Action and CN of Superior Rectus

Elevates eye & turns it medially CN III (Oculomotor)

Action and CN of Inferior oblique

Elevates eye and turns it laterally CN III (Oculomotor)

Retina

Light sensitive layer of the eye; contains rods and cones

Action and CN of Lateral Rectus

Move eye laterally CN VI (abducens)

Action and CN of Medial rectus

Move eye medially CN III (oculomotor)

Blind spot test

Position your head to look straight at the image. Cover your left eye, and look at the plus in the middle of the green background with your right eye. Move closer to the screen as before. When you hit your blind spot, the circle will disappear and the brain will fill the gap with the surrounding yellow color.

Optic disc

Region at the back of the eye where the optic nerve meets the retina. blind spot of the eye (contains only nerve fibers, no rods or cones, and is thus insensitive to light).

ciliary body

Structure surrounding the lens- connects the choroid and iris. contains ciliary muscles (controls shape of lens) secretes aqueous humor. (outer to inner-sclera, choroid, retina) Choroid-Ciliary body-iris

Cornea

The clear tissue that covers the front of the eye

Photo-pupillary Reflex Demonstration

The pupillary light reflex allows the eye to adjust the amount of light reaching the retina and protects the photoreceptors from bright lights. The iris contains two sets of smooth muscles that control the size of the pupil

What do the visual acuity test results mean?

Visual acuity is expressed as a fraction, such as 20/20. Having 20/20 vision means that your visual acuity at 20 feet away from an object is normal. If you have 20/40 vision, for example, that means you need to be 20 feet away to see an object that people can normally see from 40 feet away.

Pigmented layer of retina

absorbs light and prevents it from scattering in the eye

Fovea centralis

area consisting of a small depression in the retina containing cones and where vision is most acute

Suspensory ligament (eye)

ciliary zonule (zonule of Zinn) a series of fibers connecting the ciliary body and lens of the eye, holding the lens in place. (lens=trampoline)

Iris

flat ring-shaped membrane behind the cornea with an adjustable circular opening in the center (pupil). The Iris provides an individual with eye color.

Ciliary Zonule (suspensory ligament) googled pic

holds lens in place

Vitreous humor

jellylike substance found between the lens & retina in the posterior cavity of the eye that maintains its shape

Neural layer of retina

photoreceptors respond to light and convert the light energy into action potentials that travel to the primary visual cortex of the brain

Pupil

the adjustable opening in the center of the eye through which light enters

Optic nerve

the nerve that carries neural impulses from the eye to the brain

Choroid of eye

the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera

Sclera

white of the eye