Module 9: Neurosensory Disorders

Eyelids

Protects the eye and limits the amount of light into the eye

Canthus

Allows tears to drain into lacrimal system

Eyelashes

Filter dirt from air entering eye

Conjunctiva

Protect eye from foreign bodies and allows for inspection of tissue

Sclera

External, white layer of eye and physically supports internal structures

Cornea

Permits light into eye and lots of nerve endings to repsond to pain/touch

Iris

Circular disc, pigments determine eye color and muscles adjust how much light enters and constricts/dilates pupil for near/distance

Pupil

central aperture

Aqueous humor

Watery fluid, anterior chamber of the eye, nourishes internal eye structure

Vitreous humor

gel-like substances behind the eye-ball, holds shape of eye

Lens

Transparent and located behind the iris. Refracts (bends) light rays into the retina

Retina

Innermost layer, highly innervated. Receives visual stimuli and sends it to the brain, contains macula

Optic Disc

Cream-colored, circular area near the retina. Normally round or oval shaped and is where the optic nerve enters the eyeball

Retinal vessels

Dark red and grow narrower towards the periphery

Order of the light entering the eye

Cornea → iris/pupil → lens → aqueous humor → retina → optic nerve → brain

Myopia

Nearsightedness

Light lands in front of the retina

Hyperopia

Farsightedness

Light lands behind the retina

Presbyopia

The gradual diminished ability to focus on close objects. Normal for aging and begins around the age of 40 years old.

Astigmatism

When lights rays are diffused and spread about the retinal area either because of the shape of either the lens or the cornea. The eyeball is more of a football shape than its normal spherical shape

Amblyopia

Lazy eye

• Develops in children less than 6 years old

• Can lead to functional blindness

Symptoms of Amblyopia

eyestrain, poor visual acuity, squinting, or completely closing one eye to see.

Treatment for Amblyopia

Patch the eye with good vision to strengthen the weak one

Strabismus

Crossed eyes

Treatment of strabismus

vision therapy or surgery

Color blindness is more common in what?

In males

Etiology of color blindness

Inherited from the mother and gene is carried on the X-chromosome

Treatment for myopia, hyperopia, and astigmatism

Corrective lenses or LASIK surgery. Presbyopia can also be treated with corrective lenses

Conjuctivitis

Inflammatory process of the bulbar conjunctiva (covers the sclera) and the palpebral conjunctiva (lines the eyelid). Also known as pink eye

Risk factors of Conjunctiva

contact lenses, foreign body in eye, exposure to others, having herpes

Bacterial vs. Viral conjunctiva

Bacterial has mucopurulent exudate (gunk) and is more common in children. Viral has watery discharge of the eye and is more common in adults

Treatments of Conjunctiva

Ocular antibiotics for bacterial infections, oral and topical antiviral for herpes conjunctivitis.

Papilledema

Swelling of the optic nerve caused by an increase in intracranial pressure (ICP)

• This needs immediate intervention as its potentially life-threatening

Symptoms of Papilledema

Headaches, diplopia (double vision), V&N, and tinnitus. The borders of the optic disc can look unclear and undefined upon examination

Treatment of papilledema

address underlying pathological process causing elevated ICP, such as a brain tumor

• Untreated papilledema can lead to permanent blindness

Diabetic Retinopathy

Vascular changes that occur in the retina due to Type 1 or Type 2 Diabetes because of the high blood sugar levels

How to diagnose diabetic retinopathy

fundoscopic eye exam

Symptoms of diabetic retinopathy

floaters, blurred vision, poor night vision, vision loss, and cotton wool spots

Treatment of diabetic retinopathy

glucose control → slows progression of retinal changes

Photocoagulation laser technology is used to destroy new, fragile vessels, along with hemorrhages

Two types of Glaucoma

• Acute Angle Glaucoma - worse of the two and can lead to permanent blindness if not treated within a few hours

• Primarily Open Angle Glaucoma - the more common one

Glaucoma

Caused by the increased intraocular pressure which increases pressure on the optic nerve and results form the obstruction of the aqueous outflow.

Primary Open Angle Glaucoma Risk Factors

Over the age of 40, African American, family history, myopia, increased IOP, hypertension diabetes

Acute Angle Glaucoma Risk Factors

use of anticholinergic medication, family history, hyperopia

Symptoms of Primary Open Angle Glaucoma

can be asymptomatic, progressive vision loss

Symptoms of Acute Angle Glaucoma

N&V, halo around lights, eye pain, redness, sudden/rapid vision loss of peripheral or central vision

Diagnostics of Primary Open Angle Glaucoma

ophthalmoscopic visualization, measurement of IOP-tonometry

Diagnostics of Acute Angle Glaucoma

Redness around the eye and blood vessels of the sclera may be present, fundoscopic exam is needed to examine the optic nerve

Treatment of Primary Open Angle Glaucoma

topical eye drops to decrease IOP

Treatment for Acute Angle Glaucoma

Laser surgery to help unblock drainage so excess fluid can drain

Normal IOP

12-22 mmHg

Cataracts

Cataracts

Excessive endothelial growth in the lenses cause the lens to thicken and “cloud.” The thickening makes the lens less flexible and less likely to accommodate.

Risk factors for Cataracts

Exposure to UV light, trauma, musculoskeletal disorders, diabetes, advancing age, cigarette smoking, obesity, long term steroid use, kidney disorders

Symptoms of cataracts

gradual vision loss, painless

Treatment of cataracts

corrective lenses or surgical removal of the lens with replacement an artificial lens

Diagnostics for Cataracts

complete ocular exam with test visual acuity of both far and close distances

Age-related Macular degeneration

accumulation of drusen leads to the deterioration of the macula, causing central vision deterioration

Etiology of Age-related Macular Degeneration

combination of genetics, behavioral (smoking, obesity, hypertension, and dietary fat intake), and environmental factors

Symptoms of Age-Related Macular Degeneration

decreased vision later in life, difficulty seeing at night or in low light settings, trouble reading and seeing faces. Central vision is deteriorating while peripheral vision is intact

• Painless, slow vision loss is the hallmark sign