The Environment and its effect on dry eye symptoms
If eyes are dry then the environment can make a big difference. Any thing that increases the rate of evaporation of tears from the eye needs to be avoided. The biggest culprits are moving air and low humidity.
It is best to avoid fans and air-conditioning blowing across the eyes. This moving air is often found coming from the heating and cooling vents in cars, homes and offices. The relative humidity in a room should be around 40% to 60%. This can easily be measured by the purchase of an inexpensive hygrometer. Heating systems in winter that use reverse cycle air condition tend to be very low in humidity. In the winter the air in our consulting room is really dry at only 30% humidity! To improve the air quality a humidifier can be used in the home or under the desk in the office. We have a client with quite severe dry eye who went trekking in Vietnam during the rainy season. After 8 weeks in the high humidity over there all her symptoms had gone. When she returned to Perth her dry eye symptoms gradually returned. It is probably best to aim for humidity in the 50% to 60% range.
Computer work also presents a challenging environment. The current thinking from a posture perspective is to have the top of the monitor at eye level. The problem with this is that when looking straight ahead the eye is quite wide open leaving a larger surface area for tears to evaporate from. We suggest to our clients that they lower the monitor so that they eye naturally narrows a little when looking down which reduces evaporation. The second challenge of computers is the reduced blink rate when concentrating. The normal blink rate can half during concentrated reading. We recommend the Donald Korb Blink training app to help train blinking.
In order to lessen the impact of the environment we suggest avoiding forced air and low humidity. If this can’t be avoided then steps can be taken reduce the rate of evaporation. A pair of glasses can help to shield they eyes and there are moisture chamber glasses available with side shields to provide even more protection. The local humidity can be altered with a humidifier or even some pot plants. Maintaining good hydration helps, so that means more water and less coffee. Finally, blinking is crucial. A normal tear film should last about 10 to 15 seconds. In patients with significant dry eye it is typically 5 seconds or less. Every time a blink happens the tear film is renewed. This means if a blink occurs before the tear film breaks down then there is no irritation. This is why we are keen for clients to develop good blinking habits to help them navigate harsh environments.