Chapters 19 and 20 Disorders of Special Sensory Function Flashcards
Cornea
Most exterior portion of the eye. Clear, protective.
Where is the aqueous humour located in the eye? Function of this liquid?
Behind the cornea in the anterior and posterior chambers. Keeps the eye lubricated.
Sclera
The white part of the eye
Where is the iris? What is its function?
This is the colored part of the eye. Located behind the cornea and the anterior chamber. Responsible for constriction and dilation of the pupil in response to light.
Where is the lens? Shape?
Located behind the iris. Concave shape to reflect light for sight.
What structures are located at the back of the eye?
Retina, macula, optic disc, blood vessels
What is the uvea?
- Iris
- Ciliary body
- Choroid
Ptosis
1. Cause?
Eyelid drooping
1. Caused by muscle weakness of the levator muscle or unopposed action of the orbicularis oculi.
Function of the orbicularis oculi? Weakness vs unopposed action?
The OO closes the eyelid.
1. Weakness of this muscle can result in eyelids remaining open.
2. Unopposed action can result in ptosis
Levator muscle
Controls the eyelids opening
Ectropion
Eversion of the lower lid margin (eyelid turns out). Dry eyes.
Entropion
Inversion of the eyelid (eyelid turns inward). Infection.
Blepharitis
1. Describe the forms
2.Treatments
Inflammation of the eyelid.
1. Seborrheic form - associated with yeast (dandruff) of the scalp and brows. Kinda looks like cradle cap. Can be treated with gentle mix of baby shampoo.
2. Staphylococcal blepharitis - caused by Staph infection, lesions are often ulcerative. Usually antibiotic ointment.
Hordeolum
AKA stye
Infection of the sebaceous gland of the eyelid. Internal or external.
Chalazion
A chronic form of an internal hordeolum.
Caused by chronic inflammation of the granuloma of meibomian glands.
Dry eyes
1. What is the normal function of the tear film?
2. What are some common causes of dry eyes?
3. How can dry eyes affect a person’s health?
4. Treatment
- The tears work to lubricate the eyes.
- Common causes include - advanced age, contacts, Sjogren syndrome, loss of reflex lamrim.
- Places the patient at increased risk for inflammatory eye conditions and infection.
- Artificial tears, ointments, procedure
What is the conjunctiva? Where is it?
A thin mucus membrane that surrounds the eyelid. It works to keep the eye moist.
Conjunctivitis
1. Types
2. Treatment
Inflammation of the conjunctiva - a thin mucous membrane that surrounds the eyelids internally.
1a. Infectious - yellow drainage. Can be bacterial, viral, chlamydial, or ophthalmia neonatorum.
1b. Allergic - clear drainage.
- Most of the treatment involves antibacterial ointment or eyedrop. In regard to the neonatorum - prenatal care prevention is the best treatment.
A patient presents to the clinic with eye redness. How to differentiate between conjunctivitis vs corneal lesions or glaucoma?
- Conjunctivitis typically causes itchiness and drainage. Pain is only mild if any.
- Corneal lesions and glaucoma are serious conditions where the patient may be experiencing severe pain. Send to hospital. Need referral care.
Keratitis
1. Types
Inflammation of the cornea
1. Bacterial, Herpes simplex, Acanthamoeba
Arcus senilis
Fatty deposits found on the edge of the cornea. Seen with high cholesterol and/or age.
What part of the nervous system controls the pupil?
The ANS controls pupillary constriction and dilation. Parasympathetic controls constriction - decreased vision. Sympathetic nervous system controls dilation - allows greater light to enter the eye allowing for greater vision during times of stress.
Miotic drugs
Drugs used in Opthalmic field to controls the dilation of the pupil, typically for surgery.
Glaucoma
1. Causes
2. Risk factors
3. Signs and symptoms
4. Untreated
A form of optic neuropathy that results in cupping of the optic disc with resulting visual field loss.
- Causes
- Increased intraocular pressure (typically seen with obstruction of aqueous humour flow). This results in a gradual increase in intraocular pressure over time damaging the surrounding structures. - African Americans are more commonly affected. Family history.
- Manifestations
- Painless
- Insidious onset
- bilateral vision changes (tunnel vision, blurred vision, halos around lights, decreased color discrimination). - Untreated glaucoma can result in blindness
Angle-closure VS open-angle glaucoma
- Angle-closure - typically more of an acute onset. Severe symptoms. Emergency, can lose sight.
- Open-angle - typically more of a chronic onset. Mild symptoms. More common.
What controls the intraocular pressure?
The aqueous humor - also supplies nutrients, lubricates.
Baby with congenital or infantile glaucoma symptoms?
Excessive lacrimation and photophobia
Fussy, rubbing eyes
Grayish, white appearance of eyes
Enlargement of the optic globe
The lens
1. Describe its properties
2. How is it held in place?
3. How does it adjust for far and near-sighted vision changes? Describe the difference in lens shape during far/near vision.
- The lens is avascular, transparent.
- Thin, elastic capsule is attached to surrounding ciliary bodies of ligaments known as zonules, these hold the lens in place and also, through contraction and relaxation, allows the lens to change shape.
- During distant vision - the default - the lens is flattened as the zonules and lens capsule apply pressure. During near-vision the amount of pressure is increased producing a more convex or spherical shape.
Hyperopia
1. anterior-posterior dimension
Farsightedness - the a-p dimension of the eyeball is too short. This leads to the image being focused posterior (behind) the retina.
Have trouble seeing up close, see better far away.
Myopia
1. anterior-posterior dimension
Nearsightedness - the a-p dimension is too long, anterior to the retina.
Have trouble seeing faraway, see better up close.
Presbyopia
Changes in vision due to age. Typically results in decreased ability to see up close.
Cataract
1. Causes
Lens opacity that interferes with transmission of light to the retina. Very common.
1. Causes
- Aging
- Genetics
- DM
- Sunlight exposure
- Smoking
- Trauma or disease
Papilledema
1. Causes? Patho
2. Manifestations
Optic disc is fuzzy looking due to edema. Seen with increased intracerebral pressure seen with tumors, subdural hematomas, hydrocephalus, HTN.
The entrance and exit of the central artery and veins of the retina are located in the tough sclera tissue. When these arteries and veins are compressed can cause edema.
- Fuzzy looking optic disc
Retinitis Pigmentosa
1. Etiology
2. Manifestations
Slow degenerative changes in the retinal photoreceptors.
1. Autosomal and sex-linked
2. Early symptoms -Night blindness or bilateral symmetric loss of mid-peripheral fields. Over time the daytime and central vision can be affected too. So peripheral and central vision loss occurring gradually.
Diabetic Retinopathy
1. Types
Damage and degradation of the blood vessels of the retina caused by uncontrolled DM.
1a. Non-proliferative - damage is confined to the retina.
1b. Proliferative - formation of new fragile blood vessels as collateral flow. These fragile blood vessels are prone to rupture resulting in bleeds and could result in retinal detachment.
Retinal Detachment
1. Causes
Separation of the neurosensory retina from the pigment epithelium. Emergency.
1. Causes:
- Exudative - accumulation of fluid behind the retina
- Traction - pressure is placed on the retina through the development of scar tissue
- Rhegmatogenous - the vitreous begins to liquefy and collapse - most common.
Macular degeneration
Loss of central vision due to degeneration of the macula.
What is the retina? Where is it? What is its primary function?
1. Neurons associated
The retina is a light sensitive area of the eye that receives visual images and sends the data to the brain. It is located at the back top part of the eye.
1. There are three layers of neurons associated with the retina’s function.
- Photorecptors
- Bipolar cells
- Ganglion cells
Photoreceptors
1. Where are they?
2. Types? What do they do?
- They are located in the retina
2a. Rods - capable of black and white discrimination.
2b. Cones - capable of color discrimination.
Visual agnosia
Damage to the visual association cortex results in learned meaningfulness of visual images.
Cortical blindness
Bilateral loss of entire visual cortex
Amblyopia
Loss of vision with no detectable cause
Strabismus
any abnormality of eye coordination or alignment that results in loss of binocular vision
What is the primary role of the external or middle ear? What about the inner ear?
The external or middle ear have the primary function or capturing, transmitting, and amplifying sound.
The inner ear contains the receptive organs used in hearing.
Otitis externa
Inflammation of the external portion of the ear. Swimmer’s ear is example.
Otorrhea
Drainage from the ear
Eustachian tube
1. Functions
Tube that connects the middle ear to the back of the throat
1a. Ventilation of middle ear, allows equalization with ambient pressures
1b. Protection of middle ear from backflow from the nasopharyngeal area.
1c. Allows drainage of middle ear secretions into the nasopharynx
Otitis media
1. Why is it more prevalent in children?
Inflammation of the inner ear. Typically involves collections of fluid.
- Children have shorter eustachian tubes that are more horizontal and wider.
- Infants spend most of their day supine - this allows spread of sickness through the eustachian canal
Otosclerosis
1. Symptoms
Spongy bone forms around the stapes and oval window. Results in progressive deafness.
- Increasing pressure applied by the new bone can results in tinnitus, sensorineural hearing loss or vertigo
Tinnitus
Inner ear disorder. Perception of abnormal ear or head noises that are not produced by external stimulus. Ringing in the ears.
Hearing loss
1. Types
1a. Conductive - stimuli are not adequately transmitted.
1b. Sensorineural hearing loss - disorder of the inner ear, auditory nerve, or auditory pathways of the brain
1c. Mixed
Vestibular nuclei
Integrative center for balance - receives input from vision and somatic receptors
Nystagmus
Involuntary rhythmic and oscillatory eye movements.
Vertigo
1. Causes
illusion of motion occurs even when the patient is at a standstill
1. Brain lesion, ischemia, MS
Motion sickness
Repeated stimulation of the vestibular system overwhelms it. Car, boat, plane sickness.
Meniere disease
1. Causes
Unbalanced unilateral involvement of one of the vestibular organs.
1. Trauma, infection, immunologic, a lot
