DIS - Eye Trauma III: Chemical - Week 8 Flashcards
Where do majority of chemical eye injuries occur?
At work
Do chemical injuries tend to be urgentocular emergencies or are they self-limiting?
Are urgent
What improves visual prognosis with chemical injuries?
Immediate irrigation
List 6 factors that affect the severity of a chemical ocular injury.
Nature of the chemical
Concentration
pH
Volume
Duration of exposure
How quickly treatment is initiated
What is the main group of chemicals that causes damage? List three others.
Alkali (80%)
Acids
Surfactants
Aerosols
List two common acids that can cause injury.
Sulphuric acid
Hydrochloric acid
List 4 common alkalis that can cause injury. List some common items these chemicals are found in.
Ammonia
-household leaning agents
-fertilisers
-refrigerants
Lye
-drain/oven cleaners
-airbags
Magnesium hydroxide
-firework sparklers
-flares
Lime
-plaster
-mortar
-cement
-whitewash
What are three common sources of chemicals that cause injury?
Household cleaning products
-especially bleach
Personal care products
-especially hair products
Car products
-especially battery acid
List four things that affect the severity of a burn with acids.
Concentration
Duration of exposure
pH
Protein affinity of acid anion
What happens when an acid reacts with the anterior cornea? Does it commonly reach the anterior chamber?
Binds with tissue protein and coagulates the corneal epithelium
Proteins precipitate in the anterior cornea
Forms a barrier to further penetration
Rarely reaches the anterior chamber
Do organic acids have strong or minimal penetration of the cornea? Do they often cause severe or mild symptoms?
Minimal
-mild symptoms
Which penetrates tissue quicker, alkali or acids?
Alkali
Above what pH are alkalis exceedingly dangerous?
> 11
What does the amount of damage from an alkali burn depend on?
Fat solubility
What common household product has a strong ability to dissolve fat?
Ammonium hydroxide
What effect do alkalis have on collagen?
Destroys them
What is often seen with alkali burns of the eye?
Initial appearance can be decieving
May be worse with time
Can alkalis penetrate into the anterior chamber?
Yes
What is the major ingredient in cement and lime that can result in alkali burns? Does this account for many or few causes of chemical injury? Are they serious?
Calcium oxide in the major ingredient
Lime burns are very serious and one of the most common causes
List the three main groups of detergents. Note the charge for each.
Cationic - positive
Anionic - negative
Non-ionic - neutral
What effect do cationic detergents generally have on the eye? What about when severe?
Precipitates proteins of the cornea and conjunctiva
If severe, corneal opacification and vascularisation
What effect do anionic detergents generally have on the eye?
Heals quickly with no permanent damage
What effect do non-ionic detergents generally have on the eye?
Can produce corneal erosion, but heals without scarring
What effect do surfactants and solvents generally have on the eye (4)?
Persistent corneal epithelial defects
Stromal oedema
Endothelial cell loss
Subepithelial plaques
