Lab Twelve - Eye and Ear

Flashcards created from notes on the structure and function of the eye and ear, including visual and auditory pathways.

Optic Tract Compression

If the right optic tract is compressed due to a lesion, it causes loss of the entire left visual field.

Visual Acuity

Visual acuity is recorded as a fraction for each eye; 20/40 vision means seeing at 20 feet what a normal eye can see at 40 feet.

Photoreceptor Processing

Information from the left visual field is processed by photoreceptors in the medial half of the left eye and the lateral half of the right eye.

Blind Spot Awareness

The reason we are not aware of our blind spot is because the brain fills in the missing information.

Visual Pathway Sequence

The correct sequence for the visual pathway is: Optic chiasm, Lateral geniculate nucleus of thalamus, Eyeball (receptor), Occipital cortex, Optic nerve (CN II), Light (stimulus), Optic tract.

Near Point of Accommodation

The near point of accommodation is decreased in people with hyperopia (farsightedness).

Blind Spot Location

The blind spot of the retina is located at the optic disc and contains no photoreceptors.

Vision Comparison

If someone has 20/40 vision in one eye and 20/15 in another, the left eye has the better vision.

Astigmatism

Astigmatism is an abnormal curvature of the cornea or lens that causes light rays to be bent unevenly.

Color Blindness

Color blindness is a genetic deficiency that affects primarily males, not females.

Myopia

Myopia is also called nearsightedness; the focal point of an image falls in front of the retina.

Presbyopia

Presbyopia is caused by the loss of accommodation by the lens.

Weber Test

The Weber Test assesses for conductive and sensorineural hearing deficits.

Conductive Hearing Loss

In conductive hearing loss, sound is louder in the defective ear due to increased sensitivity in the cochlea.

Negative Afterimage

The darker image seen after staring at a colored square is referred to as a negative afterimage.

Sensorineural Hearing Loss

Sensorineural hearing loss is characterized by damage to the cochlea and/or the cochlear division of cranial nerve VIII.

Optic Chiasm Split

If the optic chiasm is split, it can cause a loss of central vision.

Rinne’s Test

The Rinne’s Test is used to evaluate hearing by comparing air conduction and bone conduction.

Sound Localization Difficulty

It is difficult for the ears to localize sound when the tuning fork is above the head at midline.

Iris

The iris is the colored part of the eye, controlling the size of the pupil.

Choroid

The choroid is the brown structure behind the retina that contains blood vessels.

Rectus Muscles

The superior rectus muscle and inferior oblique muscle are specific muscles that control eye movement.

Conjunctiva

The conjunctiva is the thin membrane covering the white part of the eye.

Cornea

The cornea is the transparent front part of the eye, covering the iris and pupil.

Sclera

The sclera is the white outer layer of the eyeball, providing structure and protection.

Lens

The lens is a transparent structure in the eye that focuses light onto the retina.

Posterior Chamber

The posterior chamber is the space behind the iris filled with aqueous humor.

Anterior Chamber

The anterior chamber is the space in front of the iris, also filled with aqueous humor.