9 - Cornea3 Flashcards
Biggest risk for any corneal ulcer
Contact lens wear
Bacterial keratitis
-epidemiology/hx
Most common etiology for infectious keratitis
- esp CLS wear
- consider all corneal infection bacterial until proven otherwise
Bacterial keratitis
-pathophys
Most common microbes: PSEUDOMONAS AERUGINOSA*, staph epi/aureus, h. flu, moraxella cararrhalis
*pseudo aur = most common gram(-) pathogen in severe bacterial keratitis; thick, green mucopurulent discharge, fast - can perforate in 48h
Most bacteria require an epi defect to invade
-exceptions: CNHL (corney, neisseria, haemophilus, listeria)
Bacterial keratitis
-signs/symp
Signs: INFECTIOUS ULCER (stromal infiltrates + overlying epi defects)
Symp: SEVERE PAIN + AC rxn, red eye, photophobia, decr vision
Describe an infiltrate
Sign of immune system attacking an antigen via antibodies
-without overlying epi defect is immune-mediated, not a sign of infection
Infiltrates start in the stroma, are signs of immune system attacking or over-reacting
Bacterial keratitis -corneal infiltrates/ulcers —infectious corneal ulcer —sterile corneal ulcer —sterile infiltrate
ICU: rare, fluoro staining area RATIO 1:1, MOD-SEVERE PAIN, mild AC rxn, DIFFUSE INJECTION
SCU: common, fluoro staining area RATIO <1:1, less pain/injection
SI: will NOT STAIN with fluoro (no overlying epi defect), multiple lesions with mild pain, sectoral injection, no AC rxn
Fungal keratitis
- epidemiology/hx
- pathophys
Most common type of corneal ulcer after injury, esp vegetable matter
Candida: pts with CHRONIC corneal disease (dry eye, herpes keratitis, esposure k) or IMMUNOCOMPROMISED
-recall: candida is part of normal flora, won’t harm unless compromised
Aspergillus + Fusarium: VEGETABLE MATTER TRAUMA
Fungal keratitis
- culture
- signs/symp
Sabouraud’s agar
Signs:
- Candida: similar app as bacterial corneal ulcer
- Aspergillus/Fusiform: epi defect with UNDERLYING GRAY-WHITE INFILTRATE WITH FEATHERY EDGES and possible surrounding SATELLITE INFILTRATE
- possible anterior chamber rxn, hypopyon
Symp: pain, photophobia, tearing, decr vision
Acanthamoeba keratitis
- epidemiology/hx
- pathophys
Rare parasitic infection
Assoc with poor cls hygiene
Common protozoa in soil, water, human mouth
Compromise of corneal epi -> invade
Infections progress slowly, often mis-dx
Acanthamoeba keratitis
- culture
- signs/symp
HEAT-KILLED E COLI CULTURE
Signs:
- early: punctate/pseudodendritic epi defect, SEVERE PAIN OUT OF PROPORTION TO SIGNS
- late: radial keratoneuritis (corneal nerve inflammation), patchy anterior stromal infiltrates -> gradually progress to RING ULCER
Symp: blur, pain, minimal discharge
Herpes simplex virus
-epidemiology/hx
DNA virus
Young pts, previous episodes and/or cold sores
Primary exposure: children 6mo-5yr, usually ASYMPTOMATIC
Recurrent infections: reactivation of latent infection in trigeminal ganglion, TRIGGER (stress, sun, fever, immunosuppression)
Herpes simplex virus
-pathophys
Tissue damage via:
- direct invasion from virus
- neurotrophic mechanism
- immune-system response
Herpes simplex virus
-signs/symp
Signs: DECR CORNEAL SENSITIVITY
-primary exposure: blepharitis and/or conjunctivitis
—B: focal vesicular lesion w/ crusting on lids/periorbita
—C: acute unilateral follicular, watery discharge, preauricular
-recurrent infection: 1) epithelial dz 2) neurotrophic k 3) stromal dz 4) endotheliitis/disciform keratitis
Symp: pain, redness, serous discharge, tearing, photophobia, decr vision
- other possible findings:
- acute unilateral anterior granulomatous uveitis
- trabecultis
- ARN
3 things that happen when the cornea is touched
Blink
Lacrimation
Miosis
*last 2 = PNS
Herpes simplex virus: recurrent infection
-epithelial disease
Corneal vesicles (SPK)
Ulcers:
- dendritic: most common presentation, rose bengal (borders) + fluoro staining (center)
- geographic: similar to dendritic but wider - irregular with scalloped borders, assoc with previous use of TOPICAL STEROIDS
- marginal: at margin of limbus
Herpes simplex virus: recurrent infection
-neurotrophic keratopathy
CN V1 issue (nasociliary)
Unique because etiology is not immune-mediated or infectious
Ulcers typically inferior, oval in app, smooth borders
Herpes simplex virus: recurrent infection
-stromal disease
Worst because of neovascularization
Accounts for 20-48% of recurrent ocular HSV disease
INTERSTITIAL KERATITIS: infiltrate with DIFFUSE NV, an immune/“WESSLEY” ring, stromal thinning, scarring*
- thought to result from ag-ab complement cascade
- by definition: STROMAL INFLAMMATION WITHOUT PRIMARY INVOLVEMENT OF EPI/ENDO
- stromal scarring = #2 cause of corneal blindness behind trauma
- recall: 90% of IK cases are from congenital syphilis
NECROTIZING STROMAL KERATITIS: rare, from direct viral invasion, severe stromal inflammation with necrosis, corneal thinning/perforation
Herpes simplex virus: recurrent infection
-endotheliitis
aka disciform keratitis
Secondary stromal edema due to IMMUNE REACTION within corneal endothelium
Disciform endotheliitis = most common form, FOCAL, DISC-SHAPED stromal edema overlying STELLATE KPs
Unlike IK, disciform is (-)stromal infiltrates, neovascularization
Herpes zoster virus
-epidemiology/pathophys
VZV = initial invading organism
- affects 95% of children by age 5
- after initial infection, transported to trigeminal ganglia (and other cell bodies) where it becomes dormant
Reactivation can result from age*, trauma, neurodegeneration, immunosuppression
*if occurs in pt <50yo, consider a medical eval for immunosuppression
Herpes zoster virus
-signs
Unilateral, follows dermatome
Pre-zoster: PRODROME of tingling, malaise, fever
Active-zoster: vesicular rash, may or may not form on lid margin -> blepharoconjunctivitis
Post-zoster: post-herpetic neuralgia, depression
-PHN: pain persisting BEYOND 1 MO after rash onset or resolution, most common complication of zoster
—severe PHN affects 7% of pts, leading cause of suicide in pts over 70
Herpes zoster ophthalmicus
- eyelid signs
- corneal signs
Lid: trichiasis, ec/entropion, madarosis, poliosis
Cornea: occurs in 65% of pts
- keratitis: punctate epithelial, anterior stromal, interstitial
- PSEUDOdendritic keratitis (active = whole lesion stains)
- endotheliitis
- keratouveitis
- keratopathy: neurotrophic, exposure
Pseudodendrites
HSV keratitis starts with small, stellate lesions -> progress to pseudodendrites
- tapered ends with NO TERMINAL BULBS
- STUCK-ON app
- ENTIRE LESION STAINS WITH RB (just edges in HSV)
- does not stain well with fluoro (unlike HSV)
Mooren’s ulcer
- who
- benign vs malignant
Rare
Older men (40-70)
No cls wear association
Benign (75%): elderly (70yoM), unilateral infiltrate, mild-mod symp, responds well to tx
Malignant (25%): younger, black males, bilateral, severe symp, responds poorly to tx, progresses relentlessly
Mooren’s ulcer
-pathophy
Painful, progressive, chronic VASCULITIS of the limbal BVs -> ischemic necrosis + PERIPHERAL ULCERATIVE KERATITIS
Idiopathic, likely autoimmune
-assoc with HEPATITIS C
Mooren’s ulcer
-signs/symp
Signs: UNILATERAL PERIPHERAL CRESCENT-SHAPED GRAY INFILTRATE -> progresses to ulcer CONCENTRIC TO LUMBUS with unique OVERHANGING EDGE
-may be self-limited or spread circumferentially and/or centrally
Symp: PAIN, often severe
-other: tearing, redness, photophobia, decr vision (irreg astig, iritis, central ulcer)
Staph marginal keratitis
-pathophys
Common
T3 HS RXN to staph AUREUS: immune over-reaction to normal staph flora on the eye (STERILE ULCER)
-typically in pts with CHRONIC STAPH BLEPH
-recurrences are common
Staph marginal keratitis
-signs/symp
Signs: multiple bilateral stromal infiltrates (esp 2/4/8/10 o’clock, where lid contacts limbus)
- assoc phlyctenule, signs of bleph and/or acne rosacea
- residual thinning, superficial NV, peripheral scarring
Symp: asymptomatic; acute photophobia, tearing, redness, decr vision
Collagen vascular disorders
- disorder examples
- symp
- corneal findings
RA, SLE
-also polyart nodosa, wegeners
Asymptomtic; significant pain, redness, decr in vision
Peripheral corneal thinning/ulcers
Uni or bilateral
May progress to encompass ENTIRE PERIPHERAL CORNEA
May be assoc with epi/scleritis, DRY EYE
Corneal deposits
- whorl keratopathy
- fleischer’s ring
- kayser-fleischer ring
WK: “Mr. Fabry whirls his CHAI-T”
-Fabry dz, Chloroquine, Hydroxychloroquine, Amiodarone, Indomethacin, Tamoxifen
FR: iron ring at base of keratoconus
KF: copper accum in pts with certain liver disorders, esp Wilson’s
Corneal deposits
- hudson-stahli line
- stocker’s line
- ferry’s line
- band keratopathy
HS: iron deposits at junction b/w mid + lower third of cornea, common in elderly, no clinical significance
SL: iron deposits on leading edge of pterygium
FL: iron deposits on leading edge of filtering bleb
BK: Ca2+ deposites within Bowman’s layer (“swiss cheese pattern”)
