Irrigation and pH Check for Unknown Substance in the Eye

Ocular chemical exposure is frequently encountered in emergency and primary care settings, where immediate assessment and intervention are required to prevent potential tissue damage and vision loss.^1,2 The pH assessment and irrigation procedure is a standardized approach that serves as a first-line intervention in ocular chemical exposure cases when the substance is unknown or suspected to be harmful.³

Primary indications include known or suspected chemical splashes, exposure to unknown substances, and persistent foreign body sensations. Contraindications are limited but include cases where globe rupture is suspected or confirmed.^4–6

Clinical studies have demonstrated that immediate pH testing and irrigation can significantly reduce the severity of chemical burns and improve outcomes.^7,8 The time between exposure and initial irrigation has been identified as a critical factor in preventing permanent ocular damage.⁹

The measurement of ocular surface pH is a diagnostic tool in emergency eye care. Normal tear film pH is maintained within a narrow range of 6.5–7.6, and any deviation from this range can indicate potential chemical exposure and tissue damage risk. Acidic substances (pH < 7.0) can cause protein coagulation and superficial damage, while alkaline substances (pH > 7.0) are particularly dangerous due to their ability to saponify cell membrane lipids and penetrate deeper into ocular tissues.¹⁰

1. Litmus or universal pH indicator strips (range 0–14) are used for the assessment.
2. The test strip is applied to the patient's tears in the affected eye, with careful attention being paid to avoid direct contact with the ocular surface.
3. The resulting color change is compared against a standardized scale to determine the pH level of the tears.

The patient’s head should be positioned at approximately 30 degrees, and tilted toward the affected side to prevent contamination of the unaffected eye.

An adequate volume of non-preserved sterile normal saline (0.9% NaCl) is selected as the irrigation medium. Alternative solutions, such as lactated Ringer’s solution or balanced salt solution (BSS), may also be used. Recent studies indicate that BSS Plus is often preferred over normal saline and lactated Ringer’s due to improved patient comfort during irrigation.¹¹ Additionally, Diphoterine, an amphoteric irrigating solution, has shown potential benefits in rapid pH neutralization for chemical eye injuries.¹² Although there is still insufficient evidence to determine the optimal eye irrigation solution.

The use of tap water is not preferred due to its hypotonicity, which can lead to corneal edema. However, immediate irrigation with tap water in the event of a chemical splash remains beneficial for reducing severity, improving healing times, and alleviating pain.¹¹

• Eyelid management: manual lid eversion or eyelid retractors can be used to irrigate the upper and lower fornices, as chemical particles may remain trapped in these areas. A novel eyelid retractor and irrigation device has been shown to improve decontamination effectiveness in simulated chemical injuries.¹³
• Quadrant irrigation:
  • Superior quadrant: direct the patient’s gaze downward and gently retract the upper eyelid.
  • Inferior quadrant: direct the patient’s gaze upward and gently retract the lower eyelid.
  • Temporal and nasal quadrants: addressed with medial and lateral gaze, respectively, with gentle eyelid retraction.

Throughout the procedure, continuous fluid collection should be maintained using absorbent materials to prevent cross-contamination.

1. Follow-up pH testing is performed after initial irrigation to assess effectiveness.
2. For acidic exposures, irrigation should continue until pH returns to 7.0–7.5.
3. For alkaline exposures, irrigation should continue until pH returns to 7.0–7.5 and remain stable for at least 30 minutes after cessation of irrigation.
4. Expect to irrigate for around 10 minutes in true emergencies. Repeat irrigating all quadrants.

The procedure demonstrated represents a critical intervention in emergency eye care. When properly executed, it serves as both a diagnostic and therapeutic measure. The simplicity and effectiveness of this procedure makes it an essential skill in emergency and primary care settings, where rapid intervention can prevent permanent ocular damage. Time to irrigation is the most critical factor in determining outcomes, with each minute of delay potentially increasing the risk of permanent visual impairment as this can lead to permanent scarring.

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.