CAN DEHYDRATION IMPACT EYE HEALTH?

Water is a critical element for the efficient functioning of the body. It keeps us hydrated, lubricates joints and mucous membranes, regulates body temperature, keeps organs healthy, energy levels high, delivers oxygen and nutrients throughout the body and flushes out waste products. We lose water through bodily functions like sweating, urinating, bowel movements and breathing. Dehydration occurs when more fluid leaves than enters the body. High consumption of caffeine, salty foods and alcohol contribute to dehydration.

The human body is made up of 50% to 65% water, but some organs, such as the eyes, contain more water than others. The percentage of water in the eye varies from structure to structure. The cornea, the front surface of the eye contains about 80% water, while the lens contains 70%. The inside of the eye is filled with two fluids, the aqueous humor in the front part of the eye (98% water) and the vitreous humor, the clear gel that fills the back of the eye (99% water). With such a high water content, the eyes are more vulnerable to dehydration than some other organs.

The body's response to fluid loss is to conserve the amount of fluid still in the body and restrict fluid output, affecting all the organs in the body, including the eyes. Symptoms of dehydration include thirst and dry mouth, decreased urination, muscle cramps, headaches, lightheadedness, sleepiness and reduced tear production. When the eyes stop producing tears, they are no longer properly lubricated, leading to dry eye, eyestrain and vision problems. If the eyes are chronically dry, the body will sometimes compensate by producing extra tears, resulting in streaming eyes. The tears produced in this case are generally not made up of the right components, so are unable to hydrate the eyes effectively, and therefore don't correct the underlying problem.

Dehydration affects the eyes and the surrounding tissue in different ways.

• Tears are essential for flushing away foreign matter in the eyes, helping reduce the risk of eye infections. Decreased tear production leads to dry eyes, redness, eyestrain, excessive watering, blurred or double vision, sensitivity to light and a gritty feeling. Allergens and dust build up, causing irritation and itchiness.
• When the body isn't well hydrated, the skin beneath the eyes begins to look dull and the eyes appear sunken due to the underlying darker structures and orbital bones being more visible. Well-hydrated skin masks the darker structures and softens the contour of the orbital bones.
• Blurred vision or double vision can be the result of unstable tear film or excess tearing due to dehydration.
• The cornea can change shape when exposed to severe dry conditions, causing an increase in shortsightedness.
• The retina is dependent on the healthy flow of blood transporting oxygen and nutrients to the eyes, which can be compromised by dehydration.
• With dehydration, the vitreous humor inside the eye can become fragmented, leading to an increase in floaters within the eye.
• Contact lenses rely on the natural moisture of the eyes to function efficiently. People who wear contact lenses are likely to experience dehydration in their eyes more than those who do not wear contact lenses. If the body is dehydrated, the eyes are not sufficiently lubricated, causing the lenses to dry out and exacerbating the discomfort of dry eye symptoms.

The best treatment for dehydration is obviously rehydrating by drinking plenty of water. By the time we feel thirsty we are already dehydrated, so drink at regular intervals to avoid getting to the stage of thirst. Increase the humidity level in the home. Dietary changes such as reducing salt and caffeine intake and eating foods rich in omega 3 or taking omega 3 as a supplement have been found to be helpful in decreasing the inflammatory impact of dry eye.

Be mindful of blinking frequently, particularly when spending prolonged time on the computer and digital devices. Each time we blink, the eyes are moistened. The symptoms of dry eye can be alleviated by eye drops or artificial tears which help by lubricating the eye and washing away foreign materials. Ask your optometrist to recommend eye drops which are most suitable for your particular needs.