Mechanical, Thermal, and Chemical injuries of the cornea - lim

basal cells cornea

1. single layer of columnar mitotic layer

2. secretes VM

zonula occludens

1. tight jxns

2. prevent intercellular movement of substances from tear film

   1. prevents pathogens from getting into cornea

gap jxns and desmosomes

1, joins wing cells to each other and to surface and basal cells

hemidesmosomes

1. anchor basal cells thru BM, bowmans, and anterior stroma

corneal nerves

1. V1

2. enteres via peripheral stroma and branches thru mid stroma towards epi

3. 3 nerve plexus

   1. intraepithelial

   2. subepithelial

   3. mid stromal

4. NO NERVES IN POSTERIOR STROMA, DESCEMENTS, ENDO

bowmans

dense fibrois sheets of randomly arranged collagen 1 fibrils

resistant to damage but does not regenerate - forms scar tissue

normal epi regeneration

1. regenerates in 7-10 days

2. constant shedding of surface cells into tear film (flattened non keratinized squamous cells)

3. wing cells move up to replace those cells

4. basal cells move up to become wing cells

5. limbal stem cells constantly renew basal cells

   1. at Palisade of Vogt

6. slow migration of basal cells occurs fro the periphery toward center of cronea

wounded ep regeneration

1. damaged ep secretes cytokines (IL 1 and TNF alpha) and growth factors (TGF B)

2. exposed corneal nerves release neuropeptides that helps w wound healing process

3. basal cell mitosis stops

4. hemidesmosomes near injury disapperas and adjacent ep cells flatten and shift to form a single layer to cover defect

5. Once defect is covered, Basal cell mitosis resumes, and proliferation fills in the defect and tight adhesions are established

6. With proper regeneration, hemidesmosomes are reestablished.

   1. needs this for propper healing

*Healing is quicker if basement membrane remainw ________

intact

• *With basement membrane damage, complete healing may take 8 week.a

corneal abrasion symptoms

1. 10/10 sharp pain,

2. foreign body sensation

3. and light sensitivity.

4. It is worse with blinking. I

5. t started when my baby scratched my left eye.

6. My left eye is watering, and it is red.

corneal abrasion cause

Result of superficial trauma to the eye

• Ex. Fingernail, paper, tree branches, makeup brush

who does corneal abrasion effect more (epi)

males - bc of occupation

and contact lens wearers

pathophys of corneal abrasion

Mechanical trauma to corneal surface result in:

• Epithelial cell loss

 Subsequent activation of dynamic and complex wound-healing process (see physiology review)

clinical presentation of corneal abrasion

1. usually unilateral

2. INJURY

3. swollen eyelid w conj injection

4. SLE

   1. corneal ep defect

      1. ABSCENCE of underlying opacification = NO infiltrate

      2. meausre it

   2. Mild AC rxn

5. positive Na/Fl stainging

what does positive NaFl staining indicate

1. defects in corneal ep

2. focal defects = punctate staining

3. abrasion = (larger staining)

corneal abrasion management MANDATORY

antibiotic to prevent infection

what od you prescribe for a corneal abrasion for a Non contact lens wearer

erythromycin 0.5% ung QID affected eye

what od you prescribe for a corneal abrasion for injury from organic material (fingernail or vegetative matter) or CL wearer

1. NEED TO COVER PSEUDOMONAL GRAM -

2. Fluroquinolone QID affected eye

3. 2 nd Generation

   1. Ciprofloxacin 0.3% Ciloxan

   2. Ofloxacin 0.3% Ocuflox

4. 4 th Generation

   1. Moxifloxacin 0.5% Vigamox

   2. Moxeza Besifloxacin 0.6%

   3. Besivance Gatifloxacin 0.3% Zymar

why are oral FQ bad

blow out tendons (tendonitis)

bad in pregnancy

how do we treat pain w corneal abrasion

1. with anterior chamber rxn

   1. cycloplegic

      1. cyclopentolate 1% BID affected eye

2. topical NSAID

   1. Ketorolac 0.4% QID affected eye

      1. can cause corneal toxicity if used excessively

3. oral NSAID

   1. OTC Ibuprofen 400 mg every 6 hours PO

should we rx topical anesthetic (proparacaine) for pain control?

NO

delays corneal healing and can cause corneal melt

how do we allow for smoother healing in corneal abrasion

1. bandage contact lens

   1. keeps eyelids from disrupting healing

2. ep debridement

3. copious lubrication

   1. OTC preservative free artificial tears Q1H to Q2H affected eye

what does this indicate

debridement

• irregular edges

when do we follow up for corneal abrasions - large and central OR bandage CL used

1 day

when do we follow up for corneal abrasions - small or peripheral

2-5 days to make sure the ep defect is improving

corneal FB symptoms

1. “I have 7/10 sharp pain,

2. foreign body sensation

3. and light sensitivity.

4. It is worse with blinking.

5. I think something flew into my left eye; I don’t wear safety glasses at work. I work in construction”

epi for corneal FB

1. males

2. workign age group

   1. high risk activities - grinding, hammering, welding, woodworking

with high velocity FB what do we worry ab

intraocular FB

pathophys of corneal FB

1. FB lodged in any 5 layers of cornea •

   1. High velocity object more likely to pierce through bowman’s and into stroma

2. 1. FB disrupts epithelium and triggers strong inflammatory response: release inflammatory cytokines (IL-1 and TNFα )

   1.  Organic material

      1.  Higher risk for microbial colonization *

   2.  Inorganic material (metal)

      1.  Can oxidize and leave deposits

3. 2. Inflammation triggers corneal edema, and cellular infiltration (Neutrophils & monocytes)

3. If FB is retained, chronic inflammation leads to stromal scarring and visual compromise

what do you see in SLE for corneal FB

1. the FB itself

2. could have or not a rust ring

   1. mean metallic FB

3. mild AC rxn

what do we look for in an intraocular FB

1. look for

   1. pupil irregularities

   2. iris tears adn transillumination defect

   3. lens abnormalities

2. check for

   1. + Seidel Test = dark waterfall effect of NaFl being washed away

      1. aq is coming out

   2. DFE to see if it made it to vitreous or retina

   3. OCT shows depth of FB

   4. ORBITAL XRAY

how do we remove corneal FB

1. get informed consent

2. Instill topical anesthetic

3. 2. Remove using spud, forceps, small-gauge needle at slit lamp

4. remove rust ring

   1. flick away deposit w needle

   2. Alger brush —> stops at Bowmans

      1. oscilaring burr knocks off corneal ep to get rust ring off

   3. if it is deep - leave it along and let it migrate up

      1. reattempt to remove 1 day f/u

5. measure size of ep defect

6. TREAT LIKE CORNEAL ABRASION

when do you f/u for FB

1. 1 day if rust ring remains

   1. if you cant get it all out and its peripheral its ok

when do we refer to ophthalmology urgently

1. if intraocular FB

2. deeper stroma is affected

recurrent corneal erosion symp

1. “Remember me?

2. I came in a few months ago because my baby scratched my left eye, and it healed since then. But I woke up this morning with

3. 10/10 sharp pain,

4. foreign body sensation and

5. light sensitivity in that same left eye!

6. It is worse with blinking.

7. My left eye is watering, and it is red…

8. but my baby didn’t scratch me ag

cause of recurrent corneal erosion

1. Damage to corneal epithelium and/or basement membrane from the following:

   1. • Previous injury (abrasion)

      1. Most common reason

   2. • Corneal dystrophies

      1. 2 nd most common reason:

      2. • Epithelial Basement Membrane Dystrophy (EBMD)*

   3. • Corneal degenerations

      1. • Band-Keratopathy

   4. • Corneal surgeries

pathophys of recurrent corneal erosion ******************************** missing info

1. RCE almost always have a predisposing condition that ”loosens” epithelium

   1. 1. Corneal dystrophies or degenerations result in change to cell-matrix interface and epithelium to basement membrane complex

   2. 2. Previous corneal abrasion/epithelial injury or surgery

      1. • In normal: Deepest basal layer adheres tightly to underlying basement membrane via hemidesmosomes

      2. • After injury: Weakened hemidesmosomes due to trapped damaged epithelial cells

   3. • Nocturnal desiccation (closed eyelid state)

      1. • Adhesion of tarsal plate to epithelium

   4. Upon awakening (openingofeyelids)

recurrent corneal erosions clinical presentation

1. unilateral - corneal abrasion hx to eye

2. bilateral (not at the same time)- corneal dystrophy

3. could impact vision

4. swollen eyelid and conj injection

5. SLE

   1. corneal ep defect or punctate defects

      1. NO infiltrate

   2. loose/irregular ep

6. NaFl staining

how do you acutely manage recurrent coreal erosion (normal)

1. treat like corneal abrasion

how do you acutely manage a RCE if medical management is inefefctive or its chronic:

1. sx management - CORNEAL SPECIALIST

what are some sx managements for RCE

1. ep debridement w diamond Burr superficial keratectomy

   1. smooths bowmans membrane

2. phototherapeutic keratectomy (PTK)

   1. laser ablation of surface irregularities

      1. doing what diamond burr does w a laser

3. anterior stromal puncture w needle or NdYAG

   1. scarring effect

whats the long term preventative management once the acute episode of RCE has been resolved

1. 5% NaCl soln QID and 5% NaCl ointment QHS of affected eye for 3-6 m —> MURO 128

   1. osmotic action of NaCl on tear film to reduce corneal edema

   2. SALT DRAWS OUT FLUID

      1. burns on instillation

2. artificial tears QID and artificial tear ointment QHS of affected eye for 3-6 mo

   1. prevent dessication of ep and protects from eyelid forces

   2. barrier from eyelid to cornea

3. Rx doxycyline 50 mg BID PO for 4 weeks

   1. decreases MMP to promote collagen production and corneal healing

   2. anti inflammatory action

4. topical corticosteroid - FML 0.1% BID for 4 weeks

f/u for long term preventative management of RCE

3 mo to confirm no recurence

1 month if on corticosteroid

chemical burn treatment

1. immediately start

2. DO THIS BEFORE YOU ASSESS ANYTHING

3. copious irrigation w saline

4. EVERT EYELID AND SWEEP FORNIX

5. Morgan lens - ER eye irrigating system

how long do you irrigate in chemical burns

1. until ocular surface pH becomes normal 7 - 7.4

2. may take 10L of soln and 30 mins

how do you assess a chemical burn once you irrigate

1. what chemical

2. how long was it in eye

3. mech of injury

   1. high pressure?

4. did they have on eye protection

what are acid burns

1. sulfuric acid - car bateries

2. acetic acid - vinegar

3. sulforous acid, hydrochlloric acid - pool

alkali burns

1. ammonia

2. lye

3. potassium hydroxide

4. magnesium hyroxide - fireworks

5. lime = cement and plaster

whats worse for the eye — acid or alkali burns

alkali

pathophys of acid burns

1. LESS severe than alkali burns

2. • Acid binds and denatures proteins on ocular surface and cause precipitation in corneal epithelium and stroma

   1. • Precipitated protein act as barrier and prevent further penetration

alkali burn pathophys

1. MORE severe than acid burns

2. • Alkali is lipophilic and saponifies fatty acids in cell membrane leading to cell death

   1. • Penetrates deeper stroma and destroys ground substance and collagen

clinical presentation of chemical burn

1. Severity of clinical signs depend on chemical type and contact time

   1. • Corneal epithelial defect

      1. • Ranging from small punctate keratopathy to large defects

   2. • Possible blanching (whitening) of limbus and conjunctiva

   3. • Possible anterior chamber reaction

   4. • Possible corneal edema

   5. • Possible increase in IOP

DONT MEMORIZE THE GRADING SCALE FOR CHEMICAL BURN

how do we manage mild burns: to promote re ep

1. OTC preservative free Artificial Tears Q1H affected eye.

how do we manage mild burns: control pain

Cyclopentolate 1% BID affected eye.

how do we manage mild burns: dec inflammation

Prednisolone Acetate 1% QID affected eye.

how do we manage mild burns: prevent infection

Erythromycin 0.5% ung QID affected eye

how do we manage moderate burn: promote re ep

OTC preservative free Artificial Tears Q1H

how do we manage moderate burn: control pain

Atropine 1% BID affected eye.

how do we manage moderate burn: decrease inflammation

Prednisolone Acetate 1% Q1H affected eye with rapid taper at day 10-14

how do we manage moderate burn: prevent infection

FQ QID

what do we do if IOP is elevated in a chemical burn (rx)

acetazolamide 250 mg PO QID for duration of IOP spike

• NOT IN SULFA ALLERGY

  • not well tolerated by pt

what do we do for severe burn (grade 3/4)

corneal specialist

they are getting an amniotic membrane (grade 3) or surgical options (grade 4)

how do we f/u for chemical burns

1 day to look for improvement

re ep may take 10-14 days

>21 days suggests permanent stem cell injury and permanent vision loss from ulceration and scarring is likely —> CORNEAL SPECIALIST

UV keratitis symptoms

1. “I have 7/10 pain

2. and both of my eyes

3. red and watery that started today. They’re also sensitive to light

4. and have foreign body sensation.

5. I am a welder, and I am supposed to wear this mask, but I forgot. I was welding yesterday.” —> delayed onset = symptoms worsen 6-12 hours after exposure

UV keratitis cause

sunburn to eye

exposure to UV rays

pathophys of uv keratitis

Transparent cornea transmits visible light spectrum (400nm to 700nm) but absorbs UV spectrum (10nm to 400nm) • 100% of UV-C (<290nm) absorbed by corneal epithelium • Protects stroma and endothelium • Damages epithelium and causes epithelial cell apoptosis

clinical presentation of UV keratitis

1. Bilateral •

2. Mild eyelid edema, conjunctival injection

3. Assessment through slit lamp •

   1. Dense, confluent, punctate epithelial defects

      1. • (+) NaFl Staining •

   2. Mild to moderate corneal edema possible

treating UV keratitis

1. will get better in 1-3 days = self limiting

2. OTC preservative free Artificial Tears PRN use.

3. Erythromycin 0.5% ung QID OU.

4. Cyclopentolate 1% QD OU.