Disorders of sensory function Flashcards
conjunctivitis
Conjuctivitis: Inflammation of the conjunctiva Causes of bilateral Infection (bacterial/fungal/viral), allergens, radiant energy Causes of unilateral Foreign body, chemical irritation/damage
Manifestations of conjunctivitis
Sensation of foreign body Scratching/burning/itching Pain Photophobia Tearing Hyperemia of peripheral conjunctiva Bacterial/fungal infection = mucopurulent discharge
Viral infection, allergy, foreign body = watery discharge
Causes and manifestations of bacterial conjunctivitis
> Streptococcus pneumonia, Staphylococcus aureus, H. influenza
Acute - manifestations
++ yellow-green exudate = sticky eyelids
Excoriation possible
> Chronic (often unilateral) > Causes - Obstruction of nasolacrimal duct - Chronic infection of lacrimal sac > Manifestations Burning, itching, morning crusting, eyelash loss, redness
Manifestations and tx of hyperacute bacterial conjunctivitis
- Neisseria gonorrhoeae (common), Neisseria meningitidis
> Manifestations (progressive) - Chemosis (edema) of conjunctiva, with redness
- Lid swelling, tenderness
- Swollen preauricular lymph nodes
> Treatment
- Systemic and topical antimicrobial
- Based on C&S swab as penicillin resistant N. gonorrhoeae common
- If untreated, corneal ulceration, perforation, vision loss
Chlamydial conjunctivitis transmission
Chlamydia trachomatis (also causes STIs) - Leading cause of preventable blindness in the world
> Transmission
- Direct contact
- Fomites, flies
- Mom to newborns
- Unchlorinated pools
> Self-limiting/mild
- More serious (stronger strain)
- Ulceration/scarring/blindness
Viral Epidemic Keratoconjunctivitis: Adenoviruses, manifestations of mild & epidemic
> Adenoviruses
- Inadequately chlorinated swimming pools
- Highly contagious (no specific treatment)
> Manifestations of mild form
Generalized hyperemia
++ tearing with little discharge
Pharyngitis, fever, malaise
> Manifestations of “epidemic” keratoconjunctivitis
Visual disturbances
Self-limiting but lasts for weeks
Corneal Trauma & Manifestations
- Minor if epithelial layer damaged as can regenerate with no scarring > Damage to endothelia - Edema (dull/hazy cornea) - Slow healing, scarring > Manifestations - Pain - Decreased visual acuity - Iridescent vision (rainbow)
Keratitis (inflammation of cornea) & causes
- Bacteria, viruses
- Herpes simplex virus, acanthamoeba (rare)
> Causes Infections, tearing defects Contact lenses Hypersensitivity reaction Ischemia, trauma Local anesthesia
Keratitis: Non-ulcerative & ulcerative
Non-Ulcerative – all layers of epithelium but leaves it intact
Ulcerative
epithelium, stroma (outer layer of iris), or both
Results in scarring, impaired vision, blindness
Disorders of refraction: Hyperopia & Myopia
> Hyperopia (farsighted- clear distance vision)
- Anterior-posterior distance of eye too short
- Image is focused behind retina
- Correct with convex lens
Myopia (nearsighted- up close objects are clear)
- Anterior-posterior distance of eye is too long
- Image is focused in front retina
- Correct with concave lens
Disorders of refraction: Astigmatism
- Asymmetric bowing/defect of cornea or lens
- Congenital
- scarring
Non-uniform refraction of light onto retina = blurred vision
Contact Lens or Surgery (to remove epithelial section)
Accommodation
Accommodation is the ability of the eye to adjust through contraction of ciliary muscles
Controlled by oculomotor nerve (CN III)
Adjusts the shape of the lens and size of pupil
Disorders of Accommodation
- Cycloplegia – paralysis of ciliary muscle results in loss of accomodation
- Presbyopia – age-related decreased accommodation (lens thickens and hardens)
- Ability to see near objects improves
Describe the etiologies and eye structure changes that occur with cataract & causes
- Most common cause of blindness
- Most are bilateral
- Fiber build-up causes layered sclerosis
Causes - Aging most common
- Hereditary, congenital
- Environmental (trauma, heat, ionizing radiation)
- Metabolic
- Drugs
- Smoking
Discuss the manifestations, diagnosis, and treatment of persons with cataract.
Manifestations - Blurred/distorted vision - Acquired myopia (second sight) - Loss of far-vision - Glare - of color discrimination Diagnosis - Snellen vision test: degree of visual impairment Treatment - Corrective lens - Surgical implants
Cite the etiology, resulting changes that occur with papilledema, & causes
- Edema of optic papilla resulting in compression of blood vessels and nerves
- Tissue surrounding optic nerve entrance to optic disc
Causes - Increased intracranial pressure!
- Tumors, subdural hematomas, hydrocephalus, malignant hypertension
Describe the change is retinal blood vessel structure that result in retinopathies
- Changes in retinal blood vessel structures Results in: - Microaneurysms: Leak plasma; edema causes haziness - Neovascularization: Fragile; leak proteins and blood - Hemorrhages: Result in ischemia - Retinal opacities: d/t all of the above
Diabetic Retinopathy (DR) due to…
> A leading cause of blindness Due to - Hyperglycemia - Hypertension - Hypercholesterolemia - Smoking
Non-proliferative: confined to retina
Proliferative: more severe d/t neovascularization
Describe the pathogenesis of non-proliferative and proliferative diabetic retinopathies and their mechanisms of visual impairment.
> Non-proliferative/background DR
- Retinal vein engorgement
- Thickened capillary membranes
- Capillary microaneurysms/hemorrhage
- Hemorrhage/microinfarcts causing leakage of exudate
- “cotton-wool spots” d/t damage to nerve fibers
Symptoms of glare
- Macular edema d/t leakage at capillary level
> Proliferative Diabetic Retinopathy
- New vessels attach vitreous too tightly to retina and resulting tension causing detachment
Discuss the pathogenesis of hypertensive retinopathy
- Increased pressure results in:
> Initial vasospasm
Ischemia/necrosis
hemorrhage
> Persistent/chronic
Compensatory arteriolar wall thickening
Ischemia/necrosis
