eye lecture terms
6 parts of the eye exam
movement of extra ocular muscles
what can you see in the anterior segment of the eye?
how can you examine the anterior segment of the eye?
Examined with simple illumination by ophthalmoscope/penlight and careful observation.
how can you examine the posterior segment of the eye?
Direct ophthalmoscope is used to assess the clarity of the refracting media
what can you see in the posterior segment of the eye?
Corneal infections (bacterial keratitis) Corneal ulcers
Usually present as red and painful, associated with photophobia.
More common in the elderly, an inward turning eyelid margin.
The margin of the lower lid is turned outward, exposing the palpebral conjunctiva..
Slightly raised, yellowish, well-circumscribed plaques that appear along the nasal portions of one or both eyelids.
May accompany lipid disorders.
a drooping of the upper eyelid
A triangular thickening of the bulbar conjunctiva that grows slowly across the outer surface of the cornea, usually from the nasal side. Reddening may occur. May interfere with vision as it encroaches on the pupil.
A harmless yellowish triangular nodule in the bulbar conjunctiva on either side of the iris. Appears frequently with aging, first on the nasal and then on the temporal side.
The patient experiences sudden severe ocular pain, severe frontal headache, and nausea/vomiting.
The eye is red and injected.
The pupil is mid-dilated and fixed.
The cornea may be hazy, causing blurry vision and the appearance of halos around lights.
THE VITAL SIGN OF THE EYE
Snellen eye chart or near vision card
Should be tested one eye at a time, with glasses or contact lenses in place if they are normally worn by the patient.
testing visual acuity
The standard method of testing visual acuity involves the use of the Snellen eye chart.
Vision is recorded as a fraction (20/20, 20/100, etc.)
20/20 = normal
The greater the denominator te less the visual acuity
Standard distance for testing is 20 feet
A person with 20/200 vision can only see the 20/200 line or greater at 20 feet. A person with normal vision could read the same line at 200 feet
refractive errors and structural defects that prevent testing visual acuity
Opacities of cornea, lens, vitreous
Optic pathway disease
How to test the function of the eye
Six cardinal directions of gaze
Tests cranial nerves III, IV, VI
- direct and consensual reaction to light
The fields extend farthest on the temporal sides. Visual fields are normally limited by the brows above, the cheeks below, and the nose medially.
The image projected on the retina is upside down and reversed right to left
where is the lesion of the optic nerve?
a lesion of the optic nerve, and of course, the eye itself, produces unilateral blindness
where is the lesion of the optic chiasm?
bitemporal hemianopsia (optic chiasm)- a lesion at the optic chiasm may involve only fibers crossing over to the opposite site. since these fibers originate in the nasal half of each retina, visual loss involves the temporal half of each field.
where is the lesion of the optic tract?
left homonymou shemianopsia (right optic tract)- a lesion of the optic tract interrupts fibers originating on the same side of both eyes. vision loss in the yes is therefore similar (homonymous) and involves half of each field (hemianopsia)
where is the optic radiation?
left homonymous hemianopsia (right optic radiation)- a complete interruption of fibers in the optic radiation produces a visual defect similar to that produced by a lesion of the optic tract
unequal pupil size
Indicative of damage to one of the four iris muscles or their innervation
Dilated (large) pupil
Sympathetic Nerve Fibers
Iris muscles dilate
Constricted (small) pupil
Parasympathetic Nerve Fibers
Iris muscles constrict
what drug can cause mydriasis?
what drug can cause miosis?
what two nerves can cause Abnormal Pupillary Light Reflexes?
Lesion of CN II (optic nerve)
Lesion of CN III (oculomotor nerve)
CN II LESION
Pupils appear equal and normal in size
Marcus Gunn Pupil (Afferent Pupillary Defect)
Since the sensory afferent (part of CN II) in the right eye is not working neither pupil constricts when it is illuminated.
What is the test for the Optic Nerve Lesion CN II?
Swinging Flashlight Test
CN III Lesion
Vision not impaired
Affected pupil dilated
CN III Lesion (oculomotor paralysis)
Ptosis (levator palpebrae m.)
EOM paralysis (MR, SR, IR, IO)
What is the test for Argyll Robertson Pupil?
Near Reaction (Accommodative Reflex)
Usually not done if direct and consensual pupillary light reflexes are normal
Neurosyphilis is the classic cause but other lesions in the region of the Edinger-Westphal nucleus (eg, multiple sclerosis) are now more common.
Cause contraction of the dilator pupillae muscle increasing the
size of the pupillary opening, which in turn increases the amount
of light entering the eye.
Also contracts the levator palpebrae superioris which elevates the
cocaine, Amphetamines (Meth)
Small pupil that reacts to light and near reaction
Causes in adults include, CVA, tumors, internal carotid dissection, herpes zoster, and trauma.
Interruption of the sympathetic nerve impulses can occur anywhere along the pathway from the brainstem to the sympathetic plexus surrounding the carotid artery
Contraction of the sphincter pupillae muscle decreases the size of the pupillary opening, diminishing the amount of light entering the eye,
Drugs heroin and morphine
> in bright light
Unilateral dilated pupil that constricts poorly to light stimulus.
Affected pupil constructs (s l o w l y) to near reaction.
More common in young women
Some patients complain of “glare” or “blurred vision” on affected side
results from damage to ciliary gangion
Repetitive, rhythmic oscillations of one or both eyes in any field of gaze, initiated by a slow eye movement.
a few beats is normal
Definition: Any deviation from perfect ocular alignment.
Inherent imbalance in pull of extraocular muscles.
Often congenital, diagnosed most commonly in
Risk of amblyopia
affected eye turned in
affected eye turned out
affected eye turned upwards
affected eye turned downwards
Latent deviation of the eyes held straight by binocular fusion
Has to be provoked to be seen (e.g., fatigue, breaking ocular fusion
But when you “break fusion” by rapidly moving an eye occluder over the affected eye and then uncover it, the affected quickly moves into correct position.
Which nerves cause Paralytic Strabismus?
Cranial Nerve III (Oculomotor)
Cranial Nerve IV (Trochlear)
Cranial Nerve VI (Abducens)
CN III Lesions (Oculomotor)
Extraocular muscle paralysis
(MR, SR, IR, IO)
(loss of direct reflex – intact consensual reflex)
CN IV paralysis
inability to move affected eye down and in
CN VI paralysis (abducens)
unable to move eye laterally
Fracture of orbital floor “blow-out fracture”
with entrapment of extraocular muscle.
is an opacity in the crystalline lens.
have gradual painless loss of vision.
macula and fovea
M- has a preponderance of cone cells and is responsible for detailed central vision.
F-The center is the thinnest part of the retina.
This area is free from any blood vessels.
The vein seems to disappear on both sides of the artery
Creamy or yellowish, often bright lesions with well-defined “hard” borders.
They often occur in clusters or in circular, linear, or star-shaped patterns.
Causes include diabetes and hypertension.
White or grayish, ovoid lesions with irregular “soft” borders. They are moderate in size but usually smaller than the disc. They result from infarcted nerve fibers and are seen in hypertension and many other conditions.
Hallmark of diabetic retinopathy
New blood vessles grow. Weak, break, bleed.