Conjunctiva

The Palpebral conjunctiva coats the eyelid, the bulbar or ocular conjunctiva covers the outer surface of the eye and protests the ant. surface of the eye with exception of the cornea and the surface of the eyelid in contact with the globe.

Rectus (superior, inferior, medial, lateral), Oblique (superior and inferior), CN II

The muscles are innervated by CN's:

III-occulomotor controls the levator papebra suerioris (that elevates and retracts the upper eyelid) and all extraocular muscles except for the superior oblique and lateral rectus muscle.

IV-troclear-superior oblique muscle

VI-abducens-lateral rectus muscle

Outer wall-sclera posteriorly and cornea anteriorly

Middle layer/uvea-choroid posteriorly cillary body and iris anteriorly

Inner layer-retina (layer of nerve fibers)

uveal tract

The iris is a circular contractile muscular disk with pigment cells that produce the color of the eye. The cerntral aperature of the iris is the pupil and is where light travels to the retina. Dialating and contracting the iris controls the amount of light reaching the retina.

The cilary body produces aqueous humor and contains the muscles controlling accomodations.

The choroid is a pigmented, vascular layer that supplies O2 to the outer layer of the retina.

Retina

Te retina transforms light impulses to electrical impulses that are then transmitted to the optic nerve, optic tract, and optic radiation to the visual cortex and then to consciousness in the cerebral cortex.

Accurate vision is achieved by focusing an image on the retina by the cornea and the lens.

Major landmarks of the retina include the optic disc,the place where the optic nerve originates, together with the central retinal artery and vein. The  macula (or fovea as it is often called) is the site of central vision. 

hyperopic, peripheral, central

Binocular vision is complete by 3-4 months

Color differentiation has developed by 6 months

Adult visual acuity is achieved by 4 years of age.

1. hypersensitivity of eye
2. changes in the refractory power of the eye
3. increased level of lysozyes in the tears causing a greasy sensation and blurred vision w/ contact lenses.
4. Worsening of diabetic retinopathy
5. Mild corneal edema
6. IOP falls during the latter half of pregnancy
7. subconjunctival hemorrhages spontaneously with labor.

Presbyopia

By 45 years of age the lens becomes more rigid and the ciliary muscles weaker. Te lens also continues to form fibers, old fibers compressed centrally form a denser central region and may cause a loss of clarity of the lens and contribute to cataract formation.

Cataract

A catartact may form because of:

1. steroid use
2. exposure to ultraviolet light
3. cigarette smoke
4. diabetes mellitus
5. aging

T or F

Blurred vision is a problem with visual acuity and there are many causes.

True

See table 11-1 for chronology of visual development

1. Failure of infant to gaze at mothers face or other objects.
2. Failure of infant to blink when bright lights or threatening movements are directed at the face.

1. decrease and/or distortion in central vision
2. use of dim or bright light to increase visual acuity
3. complaints of glare
4. difficulty in performing near work without lenses

T or F

test vision with glasses first

False

Always test without glasses first

20/200

The smaller the fraction the worse the vision. The numerator is the distance of the patient from the chart the denominator is the distance at whic the average eye can read the line.

Pinhole Test

It should result in an improvement in acuity by at least one line if refractive error is responsible for the diminished acuity.

The handheld card such as a rosenbaum pocket vision screener.

The patient will hold the card at a comfortable length and read the smallest line possible.

The confrontational test

This test in imprecise and can be considered significant only when it is abnormal. Lesions most likely to produce confrontation abnormalities include: stoke, retinal detachment, optic neuropathy, pituitary tumor compression at the optic chiasm, and central retinal vascular occlusion.

T or F

Periorbital edema may be a normal finding during an external examination.

False

It is never normal and may represent thyroid eye disease, allergies, or (especially in youth) the presence of renal disease (nephrotic syndrome).

Pain on palpation of the eye may indicate:

An eye that feels very firm and resists palpation may indicate:

1. scleritis, orbital cellulitis, and cavernous sinus thrombosis.
2. severe glaucoma or retrobulbar tumor

T or F

You would only inspect the upper tarsal conjunctiva when there is a suggestion that a foreign body is present.

True

A erythematous or cobblestone apperance may indicate an allegic or infectious conjunctivitis.

Pterygium

Occurs mostly on the nasal side and is more common in people heavily exposed to ultraviolet light. It can interfere with vision if it advances over the pupil.

The expected response is a blink, which requires intact sensory fibers of CN V (trigeminal nerver) and motor fibers of CN VII (facial nerve).

Decreased sensation is often associated with herpes simplex infection.

Lipids deposited in the periphery of the cornea are

called:

Corneal Arcus

May represent a lipid disorder and is commonly seen in individuals older than 60.

Pupillary constriciton to less than 2mm is called:

Pupillary dilation of more than 6mm and failure of the pupils to constrict with light characterize:

Inequality in pupillary size is called:

Miosis, Mydriasis, Anisocoria

Miosis can be caused by ingestion of narcotics or drugs that control glaucoma.

Mydriasis can be caused by coma (due to diabetes, alcohol, uremia, epilepsy, or brain trauma), or some eye drops (glaucoma mediations, atropine, amblyopia management in children).

Anisocoria-20% of healthy people have but reflexes are normal.Can be caused by local eye meds or unilateral sympathetic or parasympathetic pupillary pathway destruction

swinging flashlight test

Shine light in one eye and then rapidly swing to the other you should see a slight dilation in the second eye while the light is crossing the bridge of the nose but it should constrict equal to the first eye as the light enters the pupil if it continues to dilate  an afferent pupillary defect called Marcus-Gunn pupil is present.

T or F

Testing for pupillary response to accomodation is of diagnostic importance only if there is a defect in the pupillary response to light.

True

A failure to respond to direct light but retaining constriction during accomodation is sometimes seen in patients with dibetes or syphillis.

2-4mm.

Studies have shown that blacks have a rectangular, shallower orbit, Asians have a rounder orbit, and whites are somewhere between the two. There is also a reduction in ocular protrusion with increasing age.

Nystagmus

If the eye moves rapidly to the right and then slowly drifts leftward, the patient is said to have nystagmus to the right.

the balance of the extraocular muscles

A light is directed at the bridge of the nose from aobut 30cm away, while the patient looks at a nearby object. The light should be reflected symmetrically. If not perform the cover-uncover test.

In the cover-uncover test have the patient stare straight ahead at a near fixed point. Cover one eye and observed uncovered eye for movement as it focuses on the designated point. Remove and watch for movement of the newly uncovered eye as it fixes on the objedt. Repeat with other eye. If the eye tested is strabismic (crossed eye; both eyes not looking at the same place at the same time) it will fixate on te object after the "straight" eye is covered by moving, as long as the vision in the eye is good.

Deviation of movement outward is termed:

Deviation of movement inward is termed: 

exotropic- away from midline

esotropic-toward the nose

T or F

The optic disc is generally yellow to creamy pink, but the color varies with race, being darker in individuals whos skin is dark.

True

The fundus (retina) apperas as a yellow or reddish-pink background, and it varies in color as well depending on te amount of melanin in the pigment epithelium. In general they vary with the skin color of the patient just as the optic disc does.

Proliferative Diabetic Retinopathy that began as Diabetic Retinopathy and progressively got worse.

In the proliferative stage vessels grow out of the retina toward the vitreous humor that may occur in peripheral retina or on the optic nerve itself.

New vessels lack the supporting structure of health vessels and are likely to hemorrhage.  Bleeding from these vessels is a major cause of blindness in patients with diabetes.

Retinitis Pigmentosa

Earliest symptom is night blindness and hallmarks of advanced disease  exhibit bone spicule pigmentation.

1. intense ocular pain
2. blurred vision
3. halos around lights
4. red eye
5. dilated pupil
6. occasionally c/o stomach pain n&v

Chorioretina Inflammation-most common cause is laser therapy for diabetic retinopathy but may also be seen in histoplasmosis, cytomegaloviris, toxoplasmosis, or congenital rubella infections

Can help establish causal agents

Visual field defect can be detecked with a large lesion.

visual field defect

Most common cause is interruption of the vascular supply to the optic nerve.

See chart on pt 293 for examples of the following:

Bitermporal hemianopia-caused by a lesion most common pituitary tumor interrupting the optic chiasm.

Homonymous hemianopia-caused by a lesion of the optic nerve radiating on either side of the brain occuring after the optic chiasm.

Retinopathy of prematurity

35% of preterm infants 1250g or less at birth

46% of those 1000g or less

60% of infants less than 750g

Can be mild with no visual defect, or refractive error, amblyopia, or progress to retinal detachment and blindness characterized by straight, temporally diverted blood vessels on fundoscopic examination