Why Do You Check the pH of the Eye after Chemical Exposure?

Patient Presentation
A 16-year-old female came to the emergency room after having a drop of cleaning fluid splashed into her right eye. She was using bleach and trisodium phosphate cleaners to wash walls prior to painting them. She was using gloves and eye protection, but had not put the eye protection back on after taking a break from the cleaning. She and her parents immediately flushed the eye for about 10 minutes and then brought her immediately to the emergency room as she still had pain and increasing redness. She denied photophobia or blurred vision. The past medical history was non-contributory.

The pertinent physical exam showed a healthy appearing female with a reddened eye and moderate pain. The diagnosis of an alkali chemical exposure to the right eye was made. The patient’s clinical course included receiving 1 liter of normal saline flushed through a Morgan lens. Her examination showed increased pain from where the Morgan lens had been but decreased mild sclera injection. There was no photophobia and visual acuity by handheld card was 20/20. pH of the eye was ~7.0. She had tetracaine drops placed for pain relief and after irrigation with another liter of normal saline the pH was 7.3. Fluorescein testing showed no corneal abnormalities. An ophthalmologist briefly saw her and also concurred with the treatment. She was discharged with instructions to use oral analgesics for pain and to follow-up with ophthalmology if the pain increased or if she had any visual changes. She was also reminded to always use eye protection when using chemicals.

About 30% of chemical eye injuries occur at home with 60% occurring in the workplace. Splashing is the most common cause and fortunately only about 20% of injuries have significant disability. About 35% of the eye injuries are in pediatric patients. In one study of hospitalized patients for eye injuries the most common problem was an open wound of ocular adnexa (26%), followed by an orbital floor fracture (25%). Chemical eye injuries accounted for only 1.5%.

Patients with chemical eye injuries present with pain and foreign body sensation often, but they may also complain of increased tearing, photophobia and reddened eye.

Injuries appear different if the chemical is acid or alkali.

  • Acids break apart into hydrogen ions and anions. The hydrogen alters the pH and the anion causes protein precipitation and coagulation. The protein coagulation often prevents penetration deeper into the tissues and the cornea may look like ground glass.
  • Alkalis break apart into a hydroxyl ion and a cation. The hydroxyl ion saponifies of cell membranes and the cation interacts with the collagen and glycosaminoglycans.
    Stromal haze can be seen. Unfortunately these interactions can allow deeper penetration into underlying tissues. Intraocular pressure can be increased because of several mechanisms.

Learning Point
Chemical exposure to the eye is an emergency and complete history and physical examination can be deferred until initial irrigation is completed. The pH of the eye is normally neutral (7.0 to 7.3). It is important to neutralize the chemical and return the pH to neutral to avoid further eye injury. The pH is tested to help determine if the eye has been irrigated enough to remove the chemical. The irrigation must contact the corneal surface usually through a special eye irrigation system such as Morgan lenses or by opening the eye with an eye speculum. Even running water across the eye immediately after exposure begins to neutralize the chemical. One-two liters of Ringer’s lactate or normal saline solution usually is effective in neutralizing the chemicals but pH testing should be done to confirm this, and if not neutral, then continued irrigation is necessary.

Next steps in treatment include:

  • Assisting ocular surface healing – using artificial tears as burned eyes don’t adequately make tears, use of ascorbate, bandaging the eye including use of special contact lenses
  • Decreasing inflammation – using steroids, acetylcystine or other eye drops
  • Preventing infection – prophylactic antibiotic eye drops
  • Controlling intraocular pressure – using aqueous suppressant eye drops as needed
  • Pain control – ciliary spasm may cause pain and cycloplegics may assist. Often oral analgesics are enough to control the pain.

Pictures and instructions for Morgan lens use can be found here

Questions for Further Discussion
1. What are the indications for an ophthalmology consultation?
2. When do chemical exposures to the eye require surgical debridement?
3. What causes an eye injury to be serious?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Eye Injuries.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Brophy M, Sinclair SA, Hstetler SG, Xiang H. Pediatric Eye Injury – Related Hospitalizations in the United States. Pediatrics. 2006:117;e1263–e1271.

Randleman JB, Bansal AS, Loft ES, Broocker G. Burns, Chemical. eMedicine.
Available from the Internet at http://emedicine.medscape.com/article/1215950-overview (rev. 4/7/2009, cited 2/3/2010).

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.
    7. All medical and invasive procedures considered essential for the area of practice are competently performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.

  • Systems Based Practice
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.


    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital