Class 9 chapter 38 Flashcards
Conjunctivitis
Inflammation of the conjunctiva
Causes of bilateral
- Infection (bacterial/fungal/viral), allergens, radiant energy
Causes of unilateral
- Foreign body, chemical irritation/damage
Conjunctivitis manifestations
Sensation of a foreign body
Scratching/burning/itching
Pain (usually mild)
Photophobia (sensitive to light)
Tearing
Hyperemia of peripheral conjunctiva (too much blood in area)
Bacterial/fungal infection = mucopurulent discharge
Viral infection, allergy, foreign body = discharge
Conjunctivitis types
- Bacterial
- Acute
- Chronic
- Hyperacute - Chlamydial
- Viral
- Allergic
- Hay fever
- Airborne allergen
- Itching, tearing, redness
Acute & Chronic Bacterial Conjunctivitis
Streptococcus pneumonia, Staphylococcus aureus, H. influenza
1. Acute - manifestations
- + yellow green exudate = sticky eyelids
- Excoriation possible (scratch the surface)
2. Chronic (often unilateral)
Causes
- Obstruction of nasolacrimal duct
- Chronic infection of lacrimal sac
Manifestations
- Burning, itching, mornign crusting, eyelash loss, redness
Hyperacute Bacterial Conjunctivitis
Neisseria gonorrhoeae (common), Neisseria meningitidis
Manifestations (progressive)
- Chemosis (edema) of conjunctiva, with redness
- Lid swelling, tenderness
- Swollen preauricular lymph nodes (just infront of ear)
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
Chlamydia trachomatis (also causes STIs) Leading cause of preventative 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
- 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
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
Keratitis (inflammation of cornea)
Bacteria, viruses
Herpes simplex virus, acanthamoeba (rare)
Causes
- Infections, tearing defects
- Contact lenses
- Hypersensitivity reaction
- Ischemia, trauma
- Local anaesthesia
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 (far sightedness)
Anterior-posterior distance of eye too short
Image is focused behind retina
Correct with convex lens - Myopia (near sightedness)
Anterior-posterior distance of eye is too long
Image is focused front of retina
Correct with concave lens - 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)
Disorders of 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
- Cycloplegia
Paralysis of ciliary muscle results in loss of accommodation - Presbyopia
Age related decreased accommodation (lens thickens and hardens)
- Ability to see nearer objects improves (“second sight”)
Cataracts: Opacity of Lens
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
Manifestations
- Blurred/distorted vision
- Acquired myopia (second night)
- Loss of far-vision
- Glare
- Loss of colour discrimination
Diagnosis
- Snellen vision test: degree of visual impairment
Treatment
- Corrective lens
- Surgical implants
Papilledema
Edema of optic papilla resulting in compression of blood vessels and nerves
- Tissue surrond optic nerve entrance to optic disc
Causes
Increased intracranial pressure!
- Tumours, subdural hematomas, hydrocephalus, malignant hypertension
Retinopathies
Changes in retinal blood vessel structures Results in: 1. Microaneurysms Leak plasla – edema causes haziness 2. Neovascularization Fragile – leak proteins and blood 3. Hemorrhages Result in schema 4. Retinal opacities D/t all of the above
Diabetic Retinopathy (DR)
A leading cause of blindness Due to - Hyperglycemia - Hypertension - Hypercholesterolemia - Smoking
Non-proliferative: confined to retina
Proliferative: more severe d/t neovascularization
Non-proliferative 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
Bleeding
Hemorrhages/microinfarcts
Hypertensive Retinopathy
Increased pressure results in:
- Initial vasospasm
- Ischemia/necrosis
- Hemorrhage - Persistent/chronic
- Compensatory arteriorlar wall thickening
- Ischemia/necrosis
Retinal Detachment
Separation of retina from blood vessels behind it (epithelium)
Resulting painless ischemia and loss of vision in that area
Risk Factors
- Age
- Myopia (d/t stretch of retina)
- Exudative type
- Hypertension, inflammation, neoplasm - Traction type
- Fibrotic tissue/scarring from injury, infection, surgery - Rhegmatogenous (rhegma = hole) most common
- Vitreous shrinks with age, separates from retina, causes tear
Symptoms Slow painless changes in vision Beginning in peripheral vision - Flashing lights, sparks - Floaters or spots in field of vision - Shadow or dark curtain with progression
Treatment = early detection
Laser or cryotherapy to seal retinal tear
Scleral buckling
- Silicone is placed on sclera so it attaches to retina that is “loose”
