2. Chemical Burn
F.Fesharaki MD
1387

3. Chemical Injuries of the eye
Common
The offending chemical may be in the form of a solid , liquid , powder , mist or vapor.
Home , Industry, Assault
Acidic or Alkali agents are the most toxic agents.`

4. Acid Burns Acidic chemicals produce H+
The more powerful acid is more toxic
The anionic component is also important in toxicity.

5. HF is a weak acid but fluorid anion penetrates like Alkalis into the eye
Nitric acid produces yellowish epithelial opacity of the cornea
Chromic acid produces brown discoloration of cornea and chronic conjuctivtis
Sulfuric acid : in car battery

6. Acid denature and precipitate proteins

8. Alkali Burns
Raise the PH of tissues and saponification of fatty acid in cell membrane
Cellular disruption
Penetrating corneal stroma
Destroying proteoglycan ground substance and collagen fibers
Peneterating into the anterior chamber

10. Clinical Findings Epithelial defect:
Flouresceine staining of the cornea and conjunctiva.

11. Clinical Findings Stromal opacity :
Ranging from clear conea to severe stromal opacity.
Better observed after
24-36 h.

12. Clinical Findings Perilimbal ischaemia: Limbal blanching.
The limbus contains corneal stem cells

13. Ocular adnexa Skin burns Eyelid function Blinking reflex exposure
Clinical Findings
Ocular adnexa
Skin burns
Eyelid function
Blinking reflex exposure

15. Grading of Severity
Grade I: clear cornea, no limbal ischemia (excellent prognosis)
Grade II: Hazy cornea but visible iris details, less than one third of limbal ischemia(Good prognosis)
Grade III: Hazy cornea(iris details not visible) , between one-third and half of limbal ischemia (Gaurded prognosis)
Grade IV: opaque cornea and more than half of limbal ischemia (very poor prognosis)

16. Management of Chemical injuries
The most important step:
Immediate and copious irrigation of ocular surface with water or normal saline solution
1-2 litre
1-2 hours
Checking conjunctival PH

17. Removal of particulate material from ocular surface
Double eversion of upper eyelid
Paracentesis of anterior chamber

18. Antibiotic Drops
Infection prophylaxy

19. corticosteroids
Excellent inhibitors of PMN(polymorphonuclear leakocyte) function
Intensive topical corticosteroid administration is recommended for the acute phase (first 2weeks)
The dosage should be markedly reduced after 2weeks, because steroids can inhibit wound healing and increase the risk of infection

20. Oral Tetracycine Potent chelator of calcium
Inhibits degranulation of PMNs
Inhibiting PMN-induced collengenolysis

21. Topical 1% medroxyprogesterone
Effective in suppressing collagen
. Break down

22. Vitamin C 2grams of oral ascorbic acid per day
Promoting collagen synthesis
Vitamin C is a cofactor for collagen synthesis
Severe alkali burns reduce aqueous humour ascorbic acid
Potentially toxic to kidneys

23. Topical Cycloplegics Significant ant.chamber reaction
Atropine may delay corneal epithelial and stromal wound healing

24. Controlling IOP Oral carbonic anhydrase inhibitors
If corneal epithelium is healing normally, topical therapies can be used.

26. Promoting Epithelial Healing
Intensive nonpreserved lubricants
Removal of necrotic epithelium
Bandage contact lense
Tarsorrhaphy

27. Impending Corneal Perforation
Glue
Pach gralt
Penetrating keratoplasty
Conj. Flap is not recommended

28. Nonhealing epithelial Defects
Dry eye and exposure therapies
Bandage contact lense.
PTK: phototherapeutic keratectomy
Topical drug toxicity:
Benzalkalonium- chloride
Lanoline in ointments
Amniotic membrane transplantation
Limbal stem cell transplantation

29. Amniotic Membrane Transplantation
May be helpful in suppressing inflammation and promoting reepithelialization and prevention of symblepharon formation

30. Limbalstem Cell Transplantation
May be performed as soon as 2weeks after chemical injury if no signs of corneal epithelialization have appeared
Prognosis of limbal grofts is better when the eye is not very inflamed

31. Corneal Transplantion
1-2 years later .
after ocular surface reconstruction
NO inflammation
No Glaucoma
Only in binocular cases
keratoprosthesis

45. THE END