1 Mild irritation 2 Complete destruction of the ocular surface epithelium and corneal opacification loss of vision and rarely loss of the eye Offendings 1 Solid 2 Liquid 3 Powder ID: 206309
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Slide1
Chemical injuries
1. Mild irritation
2. Complete destruction of the ocular surface epithelium and corneal
opacification
, loss of vision and rarely loss of the eye.Slide2
Offendings
:
1. Solid
2. Liquid
3. Powder
4.VaporSlide3
Materials:
1.
House hold alkaline agents
eg
:
cleaners
amonia
detergents
disinfectants
2.
Industry :
chemicals, solvents , lye and acids
Slide4
The most severe chemical injuries are caused by strong alkalis and acids
.Slide5
Alkali Burns
Strong alkalis raise the PH of tissues and cause saponification of fatty acids in cell membranes and cellular disruption
.Slide6
Alkali Burns
Strong alkalis raise the PH of tissues and cause saponification of fatty acids in cell membranes and cellular disruption
.Slide7
Alkali Burns
Once the epithelium is damaged , alkali solutions readily penetrate the corneal stroma and they rapidly destroy the collagen fibers.Slide8
Strong alkaline
may also penetrate into the anterior chamber and produce tissue damage and intense inflammation.Slide9
The
limbus
contains the putative corneal epithelial stem cells , when these are damaged, the denuded surface of the cornea is often resurfaced by neighboring
conjunctival
epithelium and causes
conjunctivalization
of the cornea and vascularization, inflammation and persistent and recurrent epithelial defeats.
Alkali BurnsSlide10
Intraocular chemical penetration usually causes cataract and
glucoma
.
Alkali BurnsSlide11
In the most severe cases, phthisis
of the globe may occur.
Alkali BurnsSlide12
Classification of Severity
“Hughes classification”Slide13
Hughes classification
Modified by Ballen & Roper-Hall
Gr I
Gr II
Gr III
Gr IV
Cornea
Faint hazy
Hazy
Total loss of corneal epithelium
Opaque
Iris
Easily seen
Seen
Blurred
Obscured
Limbal
Ischemia
No
<1/3
1/3-1/2
>1/2
Prognosis
Good
Good
Guard
PoorSlide14
Acids denature and
percipitate
proteins in tissues they
contact
.
Acid BurnsSlide15
Acidic solutions tend to cause less severe tissue damage than
alkaine
solutions.
Because of the buffering capacity of tissues, as well as the barrier to penetration formed by
percipitated
protein.
Acid BurnsSlide16
The most important step is immediate and
copius
irrigation of the ocular surface with water or normal saline solution. Topical anesthetic should be instilled.
Therapy of chemical injuries to the eye
Irrigate - Irrigate - Irrigate
Slide17
It should be continued until the PH of the
conjunctival
sac normalizes.
The
conjunctival
PH can be checked easily with a urinary PH strip.
TherapySlide18
Severe chemical injuries can be
approched
by performing a
paracentesis
of anterior chamber removing 0.1- 0.2ml of aqueous humor and reforming the chamber with B.S.S to normalize the anterior chamber PH.
TherapySlide19
the next phase of therapy should be decreasing inflammation ,
controling
IOP, limiting
keratolysis
, and promoting
reepithelialization
of the cornea.
TherapySlide20
Corticosteroids are excellent inhibitors of PMN function, and intensive topical steroids administration is recommended for the first 2 weeks following chemical injuries.
TherapySlide21
The steroid should be markedly reduced after 2 weeks , because of the ability of steroids to inhibit wound healing and potentiate infection.
TherapySlide22
A deficiency of calcium in the plasma membrane of the PMNs inhibits their ability to
degranulate
, and both tetracycline and citric acid are potent
chelators
of extracellular calcium. Therefore , oral tetracycline has
theroretical
benefit for inhibiting PMN-induced
collagenolysis
.
TherapySlide23
Ascorbic acid is believed to promote collagen synthesis in the alkali-burned eye because ascorbic acid is required as a cofactor for this synthesis.
TherapySlide24
It is recommended patient receive 2 grams of oral ascorbic acid (
vitc
) per day.
TherapySlide25
A bandage contact lens or
tarsorrhaphy
may be beneficial
.
For epithelial healingSlide26
A bandage contact lens or tarsorrhaphy may be beneficial for epithelial healingSlide27
From uninvolved fellow eyes of patients
limbal
stem cell transplantation may be performed as soon as 2 weeks after injury if no signs of corneal epithelialization have appeared by that time.
Limbal transplantsSlide28
COMPLICATIONS
Non-healing
epith
defect/
conjuctivalization
/ melting (stem)
Corneal opacities
Cataract
Glaucoma/ phthisis
Dry eye
Lid
malposition
/
symblepharon
/
trichiasis
: more scarringSlide29
Prevent Injuries Before
They Happen
Many eye injuries can be prevented.
A majority of workplace eye injuries happen to workers who were not wearing adequate eye protection.Slide30
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