Many people experience red, irritated eyes after swimming, especially in the ocean. Understanding the science behind this common discomfort can help swimmers enjoy their time in the water. This article explores the mechanisms causing eye irritation and other contributing factors.
The Science of Saltwater and Your Eyes
The main reason saltwater makes eyes red is osmosis. Our tears have a salt concentration of about 9,000 parts per million (ppm), while ocean water is much higher, around 35,000 ppm. This difference creates an imbalance.
When eyes are exposed to concentrated saltwater, water is drawn out of the delicate cells on the eye’s surface and surrounding mucous membranes. This dehydration of eye cells leads to irritation, a stinging sensation, and redness of the conjunctiva, the clear membrane covering the white part of your eye.
Beyond Salt: Other Irritants in Water
While the osmotic effect of salt is a significant contributor to eye irritation, other factors in various bodies of water can also cause redness and discomfort. In swimming pools, chlorine is used to kill germs, but it can also combine with sweat, dirt, and other organic matter to form chemical irritants called chloramines. These chloramines can disrupt the eye’s natural tear film, leading to dryness, itching, and redness.
Natural bodies of water like lakes and oceans can harbor various microorganisms, including bacteria, viruses, and algae, which can cause eye infections like conjunctivitis. Fine particles such as sand or dirt can physically irritate the eye’s surface, causing abrasions and redness. Even the reflection of ultraviolet (UV) light off the water’s surface can contribute to eye strain and irritation, particularly during prolonged exposure.
Keeping Your Eyes Clear After a Swim
Preventing red eyes after swimming in saltwater or other bodies of water often involves simple protective measures. Wearing well-fitting swim goggles creates a barrier, preventing direct contact between your eyes and the water, thereby avoiding osmotic effects and exposure to irritants. After swimming, rinsing your eyes immediately with clean, fresh water or a sterile saline solution can help flush away any lingering salt, chlorine, or other particles.
It is advisable to avoid rubbing your eyes, as this can worsen irritation and potentially introduce more contaminants. Staying well-hydrated by drinking plenty of water supports your body’s natural tear production, which helps maintain a healthy tear film. If irritation persists, over-the-counter lubricating eye drops, often referred to as artificial tears, can provide relief by rehydrating the eye’s surface. If you experience persistent pain, vision changes, or discharge from your eyes, consulting a medical professional is recommended.