Back to Basics: Ocular Chemical Burns
Any chemical exposure to the eyes is a true emergency until proven otherwise. Patients with burns will often present with extreme ocular pain and may have obvious outward signs of damage such as corneal opacification or blephorospasm (involuntary closing of the eyelids). Corneal damage and damage to deeper ocular structures is determined by the pH of the substance involved and duration of exposure. As a general rule, alkaline chemicals, such as Lye used in drain cleaners or concentrated ammonia in household cleaners, generate the deepest and most serious injuries. While acidic substances cause coagulation necrosis that creates a protein film limiting spread of injury, alkaline chemicals damage through liquefactive necrosis (denaturing of proteins and saponification of fats). Liquefactive necrosis is not a self-contained process and in severe cases can lead to corneal perforation and anterior chamber involvement.
The provider should first begin immediate setup for irrigation, readying several liters of normal saline and a Morgan Lens device.
Check out this video of Dr. Al Sachetti inserting a Morgan Lens: https://www.youtube.com/watch?v=-zhtmNHrRiU
If time allows, check an initial ocular pH. This is always done in the fornix, the space between the inferior lid and the conjunctiva. The Morgan Lens must first be flushed with saline or prepared with proparacaine drops – never insert the lens dry. Proparacaine can also be placed on the eye directly prior to Morgan Lens insertion (patient may also need systemic analgesia). Run saline wide-open for 30 minutes, wait 1-2 minutes, then recheck the pH. Normal ocular pH is 6.5 to 7.5, thus if not in this range irrigation must continue for another 30 minutes. Sometimes this process may take hours and require up to 10 liters of fluid. Severe alkaline burns should be irrigated for 2-3 hours after normalization of surface pH to normalize anterior chamber pH.
After starting the irrigation process, the provider should gather more information about the chemical involved and attempt to find the pH. Do not let this history gathering delay initial irrigation. While poison control centers should be contacted for most exposures, in general substances with pH >2 or < 12 will not produce vision-threatening injuries.
Following irrigation and normalization of pH, a careful ocular exam must be performed including visual acuity, intra-ocular pressure measurement, fluorescein staining, and slit lamp exam. For all but the least serious burns that have no corneal or anterior chamber abnormalities on exam, you should consult ophthalmology emergently for further guidance.
1. “Chemical Ocular Injury” Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 8e, Chapter 241
2. Kaushik, Sangeeta MD and Steven Bird MD. “Topical Chemical Burns.” UpToDate. Last updated Sep 08, 2016.
3. Sachetti, Alfred. “Morgan Lens Insertion.” Video on Youtube.com https://www.youtube.com/watch?v=-zhtmNHrRiU