Applying a protective substance to a patient’s eyes during general anesthesia is a routine safety protocol performed by the anesthesia team. The primary goal is to prevent ocular injury and safeguard the cornea, the clear outer layer of the eye. This lubrication protects the eye from drying out or sustaining trauma while the patient is unconscious. This simple act is a highly effective way to avoid painful and temporary complications resulting from the lack of natural defenses during surgery.
The Effects of General Anesthesia on Eye Function
General anesthesia profoundly affects the body’s protective reflexes, leaving the eyes vulnerable. Anesthesia entirely abolishes the involuntary blink reflex, which normally spreads tears across the eye to maintain moisture. This loss of muscle control means the eyes cannot perform their usual defense mechanisms against dryness or foreign particles. Anesthesia also reduces tear production, disrupting the eye’s natural tear film stability. This combination of absent blinking and reduced secretion leads to rapid drying of the corneal surface. Furthermore, about 60% of patients experience lagophthalmos, where relaxed eyelid muscles prevent complete closure, exposing the cornea directly to the environment. The eye also loses the protective upward rotation of the eyeball, known as Bell’s phenomenon. The goal of the protective ointment is to create an artificial barrier that mimics the eye’s lost natural protection.
Protecting the Cornea from Environmental and Chemical Threats
The operating room environment poses three primary threats to unprotected eyes.
Environmental Dryness
Operating rooms are kept cool and have high air exchange rates, creating an extremely dry environment. This accelerates the evaporation of the already diminished tear film. Prolonged exposure to dry air can lead to a complication called exposure keratitis, where the cornea begins to break down due to dehydration.
Chemical Irritants
Harsh antiseptic solutions, such as iodine-based cleaners, are used to sterilize the surgical site. If these liquids accidentally run into an unprotected eye, they can cause severe chemical injury to the delicate ocular surface. The thick lubricant acts as a waterproof shield, deflecting these solutions away from the eye.
Physical Trauma
The risk of physical trauma is substantial during a surgical procedure involving numerous personnel, instruments, and drapes. Accidental contact from surgical tools, the edges of drapes, or even the face masks of staff can cause a corneal abrasion. A corneal abrasion is a painful scrape or defect on the corneal epithelium. The viscous ointment prevents foreign objects from rubbing against the vulnerable corneal surface.
Clarifying the Lubricant Used
The substance applied to the eyes is commonly referred to as “Vaseline” by the public, but healthcare facilities actually use a medical-grade, sterile ophthalmic ointment. This specialized product is typically composed of white petrolatum and mineral oil, which creates a thick, lubricating, and occlusive barrier. Unlike consumer-grade petroleum jelly, the medical ointment is guaranteed to be sterile and free of preservatives. Sterility is paramount to prevent the introduction of bacteria or other pathogens to the eye, which could lead to severe infection. Preservative-free formulations are utilized because preservatives found in many eye drops can irritate the corneal surface and cause inflammation. The ointment works by forming a moisture seal over the eye, keeping the cornea hydrated throughout the procedure. Anesthetists often use this ointment alongside other protective strategies. Small pieces of hypoallergenic tape may gently secure the patient’s eyelids completely closed. Taping the eyelids shut provides a physical seal, working in conjunction with the ointment to ensure maximum protection against both desiccation and external trauma.