A sauna, whether a traditional dry heat room or a steam-filled environment, exposes the body to temperatures typically ranging from 150°F to 195°F (65°C to 90°C). For the average, healthy individual, sauna use is generally safe for the eyes, provided simple precautions are consistently followed. The primary risk to ocular health stems from the rapid dehydration of the eye’s surface, which causes temporary discomfort and irritation due to the accelerated evaporation of the natural moisture layer.
How Extreme Heat Affects Eye Hydration
The high ambient temperature and often low humidity in a traditional sauna accelerate the evaporation rate of the precorneal tear film covering the eye’s surface. This tear film is a complex, three-layered structure composed of an outer lipid layer, a middle aqueous layer, and an inner mucin layer. The lipid layer, produced by the meibomian glands, is designed to slow the evaporation of the underlying aqueous layer.
The intense heat destabilizes this delicate balance, causing the protective lipid layer to break down more quickly than usual. When the lipid layer fails, the aqueous layer, which provides moisture and nutrients, rapidly evaporates into the dry, hot air. This rapid drying leads to temporary ocular surface stress, often manifesting as a gritty sensation, burning, and redness.
The loss of moisture can temporarily compromise the integrity of the corneal epithelium, the outermost layer of the eye. While the effects are typically transient and resolve shortly after exiting the sauna, this dehydration can cause tiny, superficial micro-abrasions on the cornea. People tend to blink less in extreme heat, which further compounds the problem by reducing the spreading of the remaining tear film.
Specific Risks for Vulnerable Ocular Tissues
Chronic Dry Eye Disease (DED)
Individuals with Chronic Dry Eye Disease (DED) are uniquely susceptible to damage and extreme discomfort in a sauna environment. Their already compromised tear production or excessive tear evaporation is severely exacerbated by the heat. This can lead to significant corneal irritation and trigger a cycle of inflammation that may take days to subside.
Contact Lens Wearers
Contact lens wearers face distinct risks and must remove their lenses before entering the sauna. The heat and dryness can cause the soft lens material to dehydrate rapidly, leading to the lens adhering tightly to the cornea and risking epithelial damage upon removal. Furthermore, the warm, moist conditions, especially in steam saunas, create an environment favorable for the proliferation of microorganisms. This significantly increases the risk of serious eye infections, such as Acanthamoeba keratitis.
Glaucoma Patients
Sauna use introduces a complex factor for patients with glaucoma, a condition characterized by damage to the optic nerve often linked to elevated Intraocular Pressure (IOP). While the consensus on the long-term risk is mixed, some studies suggest that heat-induced changes in blood pressure and body temperature can temporarily raise IOP in certain individuals. Due to the potential for a pressure spike, individuals with this condition should consult their ophthalmologist before incorporating saunas into their routine.
Post-Surgical Patients
Anyone who has recently undergone eye surgery, such as LASIK, PRK, or cataract removal, must strictly avoid saunas. Corneal healing is compromised for several weeks to months following these procedures. Exposure to intense heat and moisture increases the risk of infection and inflammation, so ocular surgeons typically mandate an avoidance period of at least 30 days to ensure proper wound healing and corneal stability.
Essential Protective Measures During Sauna Use
The most direct way to mitigate the risk of ocular dehydration is to limit the duration of exposure within the sauna chamber. Keeping sessions brief, ideally under fifteen minutes, reduces the total time the tear film is subjected to evaporative stress. Consciously closing the eyes for short periods during the session is a simple yet effective technique that prevents direct exposure of the ocular surface to the ambient air.
Systemic hydration is another defense, as drinking plenty of water before and after the session supports overall body fluid balance, which includes the aqueous components of the tear film.
- Use preservative-free lubricating eye drops immediately before entering the sauna to supplement the natural tear film and provide a temporary buffer against evaporation.
- Apply a second application of drops immediately upon exiting to help re-establish moisture.
- Always remove contact lenses before entering the sauna to eliminate the heightened risk of lens-related complications and infections.
- Tight-fitting, heat-resistant protective eyewear or an eye mask can be used, particularly in infrared saunas where the heat source is directly radiating, to shield the eyes from the most intense effects.