There are occupational hazards in any field, and the office-based ones are not exempt. Workers who spend long hours viewing computer monitors exhibit changes in their eye secretions, making the composition of their tears very similar to that of tears in people with dry eye disease. This was the finding of a new study conducted in Japan. The results were published on June 5 in JAMA Ophthalmology.

The tear fluid that protects and lubricates the eye contains a protein called MUC5AC that is secreted by specialized cells in the upper eyelid. The Japanese researchers found that in those who stare for long periods at computer screens, the levels of MUC5AC in their tears wear almost as low as in the tears of people with authentic dry eye disease.

“To understand patients’ eye strain, which is one of major symptoms of dry eye disease, it is important that ophthalmologists pay attention to MUC5AC concentration in tears,” said study author Dr. Yuichi Uchino, an ophthalmologist at the School of Medicine at Keio University in Tokyo. “When we stare at computers, our blinking times decreased compared to reading a book at the table.”

In addition to less frequent blinking, computer monitor viewers tend to draw their eyelids back off of their eyes more than they do while completing other tasks such as reading a book. This behavior exposes more of the eye to air and increases the loss of tear film to drying.

The researchers sampled tears from both eyes of 96 Japanese office workers, roughly two-thirds of which were men. They then measured the concentration of MUC5AC as a proportion of total protein amount in the tears. The amount of MUC5AC in the tears of workers who looked at screens for more than seven hours per day was, on average, 38.5 percent lower than the amount in the tears of workers who spent fewer than five hours a day looking at screens.

Among the subjects, 14 percent were diagnosed with dry eye disease and had 57 percent less MUC5AC in their tears compared without dry eye disease.

Previous studies indicate that workers with dry eye disease-like symptoms are less productive and at higher risk of being depressed.