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The Optical Knowledge Portal
Information – Education – Certification

Dry eye syndrome

Burning and tired eyes, contact lens intolerance and lacrimal gland dysfunctions ... many people experience problems like these every day.

Computer technology has become an integral part of our daily lives. In addition to making work much easier, it ensures efficiency and speed in business operations. However, when working on the computer, we no longer use dynamic vision; in this sense today’s office work differs from older office tasks such as sorting out the filing. Our eyes only need to focus on a screen that can be viewed using a small visual angle. Consequently, the dynamic visual process has evolved into an almost static process, which means that natural reflexes such as eye blinking when changing our viewing direction are suppressed. The blink rate often decreases from 20-25 blinks per minute to just about 2-4 blinks per minute.

Blinking restores the tear film on the eye’s surface and distributes the lipids of the tear film. Lipids are fatty oils that form the outer layer of the tear film and primarily serve to reduce evaporation from the underlying watery (aqueous) layer. Since the blink rate is significantly reduced during computer work, the thickness of the lipid layer also decreases by around 25%, reducing the tear film stability time by around 45%.

As a result, the watery layer evaporates faster than usual. The eyes become strained, red and itchy, often leading to headaches, fatigue, and loss of concentration.

Dry eyes can also be caused by Meibomian gland dysfunction. This phenomenon is referred to as “hyper-evaporative dry eye (= increased evaporation)” and can sometimes even lead to contact lens intolerance, loss of visual acuity and sore eyes.

About 20-30 Meibomian glands are embedded in the tarsal plate of the eyelid and secrete an oily fluid that mixes with the tear fluid produced by the lacrimal glands and thus prevents evaporation of the eye’s tear film.

Whereas dry eyes associated with infrequent blinking result from the insufficient spread of lipids and hence increased evaporation of the aqueous layer, dry eyes associated with the blockage of the Meibomian glands result from a lack of lipids.

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Courtesy of
OPTIK-AKADEMIE

Dry eye syndrome1
Dry eye syndrome2
Courtesy of

OPTIK-AKADEMIE