ocular disease Flashcards
alkali chemical burn
- This are the most common chemical burns because more accessible. ie. cleaning agents, fertilizer (ammonia); anything with OH, fireworks, flames, cement ( and cement like things), mouthwash and airbag residue
- worse prognosis - raise tissue pH , leads to break down of fatty acids in the cell membrane - more alkali solution can penetrate
- takes about 1 min to penetrate
acidic chemical burn
hydrofluoric acid ( glass polisher, industrial cleaner, rust removal), sulfuric acid ( fertilizer batteries) nitric acid ( fertilizer, explosives) etc
less common and less severe compared to alkali chemical burn
what are signs and symptoms of someone with a chemical burn?
Signs:
- corneal ( SPK - sloughing off epithelium)
- injection ( conj, ciliary ( ie. ACA branches injected)
- conj: chemosis and injection , hemes
-A/C rxn
- high IOP
- blanching/ turning white sclera/limbus = BADDD - means ischemia
symptoms:
- pain ( corneal nerves/ conj nerves)
- decreased vision/ photophobia ( cornea affected - spk etc)
- FBS (chemosis etc)
- tearing
- blepharospasm
what is the most common cause of alkali burns ?
calcium hydroxide
fluorescein dye
water soluble - dissolves in aqueous Layer of the tears
helps us look for corneal epithelial defects (ie. stains defects) and tear film quality( lacrimal lake, tear meniscus, TBUT
how do you treat a chemical burn
irrigate till you reach a pH of 7.0 , ( check pH every 15-30 mins)
AT’s, topical antibiotic, steroid once epithelium is healed if needed?, cyclo, amniotic membrane
Steroids- why should you be careful?
overuse can lead to corneal melting, taper off
Corneal abrasion signs and symptoms
pain - extensive network of corneal epithelium nerves
FBS
photophobia/ decreased VA (depending on location)
A/C rxn
miotic pupil - due to reflex cornea sends signal to iris
signs: staining of defect
How long does it take for a corneal abrasion to heal?
- small abrasions - heal in a few hours
- larger abrasions can take overnight
- peripheral lesions heal more slowly because limbal stem cells can be affected
remember entire corneal regeneration takes 7-14 days. see phys notes on how the cornea regenerates
see linear vertical corneal scratches
check upper eyelid for foreign body
- prior to foreign boy removal check VA
Rust ring caused by a metallic foreign body
recurrent corneal erosion
this is a repeated spontaneous disruption of the corneal epithelium.
Occurs due to improper formation of hemidesmosomes ( ie. anchor basal cells to the basal lamina) or abnormal basement membrane that is not properly attached to the corneal storm ( EBMD).
can also be age related because as we age epithelial cells secrete more basal lamina - penetration of anchoring fibrils causes epithelium to be loosely attached to stroma
MMP’s = enemies can mess with the healing process - use doxy to help with healing
Seidel sign - shows if a wound leak exists
signs of a ruptured globe/ penetrating injury
laceration,
hemorrhage, hyphema
EOM restrictions,
low IOP, Seidel’s sign,
commotio retinae,
RD/ choroidal rupture
Hyphema causes
- trauma
- disease: sickle cell (recurrent hyphen), clotting disease
- idiopathic ( using any blood thinners? NSAIDS, apirin, warfarin, clopidogrel, dipyradale)
How does a hyphema occur?
due to injury of iris or CB
Treatment of hyphema
- do not do gone/ scleral depression up to 1 month post injury ( can cause rebreeding = worse)
- B scan to check for RD
8 ball hyphema: black hyphema covering 100 % of the anterior chamber
microhyphema
can only see RBCs suspended in AC with a slit lamp
uses of a B scan
- when opacification/ something blocking view of posterior segment
- ONH drusen
- distinguishing between a choroidal nevus vs melanoma ( hallow inside)
due to posterior pigmented epithelium of iris hitting lens
See a vossius ring + hyphema
means trauma!!!
subluxation of a lens
# 1 cause = TRAUMA
- another = Marphans
= iridodialysis = separation of iris root from CB
- NOTE: iris root = thinnest part of iris , thickest = collarette
corneal blood staining
can occur as a result of hyphema, rebleeds, High IOP
- the endothelial cells are compromised, allowing hemoglobin and hemosidern to enter the storma.
hyphema secondary effects
- corneal blood staining
- glaucoma : high IOP due to RBC blocking TM (ie. decreasing outflow) - to prevent this elevate head at 30 degrees so blood cells settle inferiorly.
Idiopathic hyphema - what to do
- ask about blood thinners
- CBC + prothrombin time/partial thrombopastin time (PT/PTT)
- sickle cell screening ( AA and Mediterraneans)
What to do if you suspect a metal foreign body?
DO NOT ORDER MRI
foreign bodies that can cause inflammation
iron, steel, copper, vegetable matter
inert foreign bodies
glass, stone, precious metals, plastic
can stay in the eye long periods without causing inflammation
blow out fracture
floor fracture
- floor is made of “ my Pal Z’s on the floor”
- maxillary, palatine, zygomatic
- weakest bone = maxillary
- thinnest bone = ethmoid
NOTE: susceptible to sudden increase in IOP,
- what sinus is below the maxillary bone?
maxillary sinus
- if the patient has trauma to the globe, where is the eye most likely sitting in
maxillary sinus because the floor is the most likely one to fracture
- 3 things that run along the floor and both these things can be affected with a floor fracture
IR (inferior rectus), V2, IO
Remember V1 is above the eye and V2 is below the eye
Number of branches in V2 and how a orbital fracture can affect them.
2 – infraorbital and zygomatic
If the infraorbital nerve is affected – can have a loss of sensation in the cheeks ( when comparing the 2 cheekbones – can have hypoesthesia in that area)
If the IR is affected and trapped – the patient has trouble looking up
forced duction test
(+) means that there is restriction
(-) means that eye can move
sign of a orbital fracture
creptius = crackling when palpation of the medial orbital area or after nose blowing
how do you limit the risk of an orbital infection following orbital fracture?
do not sneeze
when do you get a positive forced duction test?
orbital floor fracture
brown syndrome ( affects SO muscle/ tendon - can be tight/ too short)
Grave’s opthalmopathy
what is a negative forced duction test associated with?
cranial nerve palsy
Commotio retinae
when the photoreceptor outer segments are disrupted and the RPE is damaged. — retina is edematous/ white ( takes hours to develop)
result of trauma, vitreous hitting back of the eye
no treatment observe (3-4 weeks)
called Berlin’s edema if at macula = retinal concussion (mild), retinal contusion ( if with VA loss and severe)
purtscher’s retinopathy
Has to do with chest compression trauma
see CWS, hemes, educates
what else can cause putscher’s like retinopathy?
acute pancreatitis
renal failure
long bone fractures
choroidal rupture
can be caused by trauma
usually seen in the temporal post pole
can cause CNVM
conditions that can cause CNVM
ie. break in Bruch’s ie. PED
C - choroidal rupture
H - histo ->. choroiditis
B - bests -> RPE degen due to lipofusion accumulation
A - angioid streaks -> decrease elastin ( middle layer of Bruch’s)
L - laquer cracks - > stretch
A - AMD - drusen accumulates in the inner collagenous zone of Bruch’s
S - Scar
eyelid ecchymosis
= black eye ie. blood vessels leading in subcutaneous
tissue
