Ophthalmic — USMLE Step 2 CK Notes

Central retinal artery occlusion: Painless monocular vision loss

Pupil fails to react to light but does react to light in opposite eye

Ocular movement intact

Pallor of optic disc, macular edema, thin arterioles

Whitened retina d/t ishaemia

Central fovea appears red from underlying choroid (cherry red spot)

Sausage like narrowing of retinal veins

Amaurosis fugax: emboli from ipsilateral carotid A

Central retinal vein occlusion: Retinal hemorrhage and venous engorgement Central Retinal Vein occlusion has hemorrhages

Central Retinal Artery occlusion does not as no blood getting to retina!

Spared Eye Injury

Immune mediated inflammation of one eye after penetrating injury to other eye

—> ant uveitis, papillary edema and poss blindness; perilimbal flush

D/t uncovering of hidden Ags

Bacterial Conjunctivitis

Most d/t Staph aureus in adults -> Thick purulent eye discharge

Typically present at corners of eyes and reaccumulates within minutes of wiping

Unilateral or bilateral (Usually bilateral)

Lasts 1-2 wks

Chylamidia and Gonnorrhea often have concurrent urogenital infections in adults

Viral Conjunctivitis

Scant, mucoid and watery discharge that causes gritty sensation in eye

Frequently associated with URT manifestations: sore throat etc

Unilateral or bilateral

Tx: cold moist compresses; antihistamines/decongestant drops

Lasts 1-2 wks

Allergic Conjunctivitis: Always bilateral

Clear, Watery discharge with mild crusting

Ocular pruritus, conjunctival injection and eyelid oedema

No purulent discharge, visual changes or pain

HSV (keratitis)

Vision threatening infection of cornea

Eye pain, blurred vision, watery discharge

Unilateral, photophobia and decreased vision

Branching/Dendritic ulcerative lesions on cornea

Pseudomonas

Ulcerative keratitis

Contact lens wearers

Trachoma:

Spreads in crowded and unsanitary conditions

Conjunctival injection, pale follicles

Follicular conjunctivitis (thickened) and pannus (neovascularisation) in cornea

Concomitant nasopharyngeal infection

Repeated chronic infections leads to scarring of eyelids and inversion of eyelashes

===> trichiasis ===> blindness

Tx: Oral azithromycin or surgery for trichaisis

Blepharitis: Inflamm of eyelid margin

Often bilateral, redness and swelling

Burning/itching of lids, discharge (poss crusting)

Foreign body sensation (grittiness)

Tx: supportive

Associated with seborrhagic dermatitis

Episcleritis: No overt pain or deterioration in visual acuity

Acute redness and tearing with injection of conjunctival and episcleral vessels

Mild irritation

Dacryocystitis: Infection in lacrimal sac

Infants and pts over 40

Sudden onset pain and redness in medial canthal region

Poss purulent discharge, fever and elevated WBC

Staph and Strep

Chalazion: Chronic Granulomatous inflamm -> blockage of Meibomian tear gland

Lid discomfort

Hard, painless lid nodule

Occurs most commonly in rosacea or Blepharitis

More common on upper eyelid (more meibomian glands)

Anterior uveitis (iritis and iridocyclitis): Pain and vision bad!!!!!

Acute redness and tearing

Hyperaemia at junction of sclera and cornea (ciliary flush), pupillary constriction,

Hazy flare in aq humor, hypoyon

Associated w systemic inflamm disorders

Aminoglycoside Toxicity

Bilateral, not necessarily symmetric, sensineural hearing loss

Imbalance and oscillopsia (objects in visual field oscillate) -> bilateral vestibular systems affected

——> cf true vertigo which generally occurs on one side

Positive head thrust test

Other ototoxic drugs: Sensineural hearing loss

Cisplatin; high dose salicylates

Loop diuretics

Presbycusis (age-related hearing loss)

D/t cochlear hair cell loss and cochlear neuronal degeneration

High frequencies affected first (inability to hear female or child’s voice); Tinnitus often develops

Tx: Limit background noise; hearing aids

Otosclerosis: Hear better in noisy environment

Allergic rhinitis: Pale/bluish nasal mucosa

Watery rhinorrhea, sneezing, eye sx

Other allergic disorders

Tx: Intranasal glucocorticoids; Antihistamines

Non allergic rhinitis: Later onset of >20 w Erythematous, boggy nasal mucosa

Nasal congestion, rhinorrhea, sneezing, post nasal drip

No obvious allergic trigger

Tx if mild is intranasal glucocorticoids or antihistamines

Moderate to severe: Combination Tx

CSF Rhinorrhea

Accidental trauma most common: fracture skull base (eg cribiform plate, temporal bone)

—> can be immediate or delayed onset (days to months)

Surgical trauma; non trauma (elevated ICP)

Unilateral watery rhinorrhea with salty/metallic taste

—> increases when bending forwards, straining etc (increases ICP)

Poss complication: Meningitis d/t nasal flora contamination of CSF

Dx: Test for CSF specific proteins in nasal discharge: beta 2 transferrin; beta trace protein

Imaging with intrathecal contrast

Endoscopy +/- intrathecal fluorescein dye

Management: Bed rest, head of bed elevation, avoid straining

Lumbar drain placement

Surgical repair

Otitis Externa (non malignant) RF: Water exposure; trauma (cotton buds); foreign material (hearing aid);

Dermatological issue: eczema; contact dermatitis

Pseudomonas (most common); Staph ===> fluoroquinolone covers for both

Otalgia, pruritic, purulent discharge (obscures tympanic membrane)

Ear canal erythema, edema, debris

Tympanic membrane spared (clear, not inflamed, no middle ear fluid)

Tx: topical Ab (fluoroquinolone) +/- glucocorticoid

Necrotising (Malignant) otitis Externa (osteomyelitis of skull base)

Risk Factors: Age >60, DM; Cerumen removal (aural irrigation)

Severe, unremitting ear pain (worse at night and with chewing)

Erythema of ext canal

Deficits in lower CNs: facial, vagus, accessory etc

Granulation tissue in ext auditory canal with white drainage (prominent discharge)

Elevated ESR

Tx: IV antipseudomonal eg ciprofloxacin +/- debridement

Optic Neuritis: Afferent pupillary defect (paradoxical pupillary dilation with flashlight)

Acute, monocular vision loss and pain with extraocular movement

Unilateral optic disc edema

Washed out colour vision

Central scotoma

Optic Nerve Injury

Acute vision loss (not necessarily total eg inability to perceive light; decreased colour vision)

A relative afferent pupillary defect (RAPD) Normal red reflex

Dx: CT orbit

Management: Urgent ophthalmology referral +/- surgical decompression

Open globe injury

Blunt force trauma (rupture) or Penetrating trauma (laceration)

Most commonly occurs at the cornea

Extrusion of vitreous

Eccentric or teardrop pupil (iris stretching d/t laceration or foreign object)

Decreased acuity and intraocular P

Relative afferent pupillary defect

Management: emergency ophthalmology consult; Eye shield; CT eye; IV Abs; Tetanus prophylaxis

Retinitis Pigmentosa: midperiphery (highest density of rods)

Genetic (sporadic but hereditary more common) mutation causing loss of photoreceptors

Progressive retinal degeneration

Sx onset from age 10 through adulthood

Night blindness

Progressive visual field loss

==> increased clumbsiness; photopsias (flashing lights) adj to scotoma (blind spots)

Decreased acuity (late finding) ==> cone degeneration in central retina

Poss cataracts

Fundoscopy: Retinal vessel attenuation; optic disc pallor; abnorm retinal pigmentation

Px: Most legally blind by age 40

Open Angle Glaucoma==> start tx even if asymp as vision loss irreversible

Loss of peripheral vision in association with an enlarged optic cup and

Increased cup/disc ratio (cupping of optic disc) >0.6

Atrophy of optic nerve head: Pale disc wThinning of disc rim

Associated with increased IOP (tonometry)

Elevated in Blacks, DM and those with Fam Hx

Insidious or steroid induced (decreases aq outflow->increase IOP —>> blurriness d/t corneal edema)

Tripping over objects, near miss vehicle accidents

Screening not norm recommended

Dx: Tonometry and gonioscopy (measures corneal angle)

Tx: Topical agents: bimatoprost (decrease volume and pressure of aq humour)/

timolol (reduces aq humour production)

pilocarpine (ciliary muscle contraction to open trabecular meshwork at corneal angle

Apraclonidine (decrease aq humour production and increases outflow)

========== —> Combination tx

Systemic drugs: IV Acetazolamide (consider mannitol) (if n/v); Laser trabeculoplasty/ iridotomy

Acute Angle closure glaucoma

HA, nausea, blurry vision and sluggish/dilated pupil

Can be spontaneous

Precipitated by anticholinergics eg trihexyphenidyl; decongestants, antiemetics

Epinephrine CI -> MYDRIASIS

Flourescein Dye used to inspect Cornea: Foreign body; abrasion; keratitis

Macular Degeneration: Central vision loss, progressive

Subretinal drusen and pigment anomalies

Distortion of straight lines such that they appear wavy (grid test)

Hypertensive Retinopathy: flame Hemorrhage, cotton wool spots -> acute

Blurred vision, sometimes with limited visual field defects

Most asym but retinal haemorrhage can cause painless monocular vision loss

Arteriovenous nicking, Copper wiring (chronic) and optic disc edema

Diabetic retinopathy: Microaneurysms, hard exudates and retinal Hemorrhages

Sometimes neovascularisation

Disc normal; Retinal/macular oedema

Visual defects (if present) are patchy

Prevention of complications; Argon laser photocoagulation

Absent Red Reflex:

Opacity of cornea (infection/scar) or lens (cataract); Vitreous hemorrhage; retinoblastoma

Vitreous hemorrhage: diabetic retinopathy

Sudden loss of vision w onset of floaters

Fundus hard to visualise and details obscured

Dark red glow

Tx: Conservative eg upright position during sleep

Presbyopia: Loss of elasticity of lens

Papilledema: Enlarged blind spot

Retinal Detachment

Sudden onset Photopsia: Flashes and floaters

Curtain coming down

Inciting incident can occur months before: Myopia or trauma eg cataract surgery

Grey elevated retina

Tx: Laser therapy and cryotherapy to create adhesions

Myopia: Complications: retinal detachment and macular degeneration

Corneal Abrasion

Red, painful eye

Often foreign body sensation

Meiosis often present 2/2 to pain

Dx: Fluorescein dye and inspection under cobalt blue light: abrasion appears green

Tx: Abs, anaesthetics and patching

Age-related cataracts: Difficulty driving at night; halos around bright lights

RF: >60; Chronic sun exposure; DM; Glucocorticoid use; Smoking; HIV

Sx: Gradual loss of acuity (blurry vision); excessive glare, Myopic shift

Opacification of lens; Loss of red reflex

DM: excess glucose —->> sorbitol (accumulates in lens and increases osmotic and oxidative stress)

Platinum based chemo ototoxicity: Cisplatin

Dose dependent

Sensineural hearing loss; Tinnitus and/or imbalance

Hyphema: Traumatic hit to eye

Blood in anterior chamber of eye: between iris and cornea

Pain and decreased vision