Bita Heidarzadeh, M.Optom
Senior Training Manager, Vision Science Academy, Turkey
Vision Science Academy Exclusive
What is Dry Eye?
Dry eyes are caused by a lack of an effective lubrication in the eyes. Tears offer a unique protection to the outer layers of the eye, but this condition leads to an inadequacy of the tear film formed over the surface of cornea and sclera. Dry eyes cause a series of irritable symptoms including an itchy sensation in the eyes, photophobia, conjunctival congestion, and blurred vision (“Dry eye”).
A multitude of causes exist for dry eyes and can range from hormonal variation to climate changes. Here in this article, we discuss a typically less common cause of dryness of eyes i.e., an excessive exposure to visual display units (VDU).
Can Visual Display Units cause Dry Eye pathology?
Human eyes are adapted to blink involuntarily throughout life, a phenomenon which is believed to be regulated by neuronal centres such as basal ganglia and reticular formation. It has been observed that the overall rate of blinking is drastically lessened during tasks that demand a continuous visual attention as well as emotional input. That is why looking at a VDU (e.g., a computer or a smart phone screen) leads to a drop in the blinking rate, and subsequently creates a less firm tear film over the exterior surface of eyes.
This observation has been consolidated by one study where it was concluded that by continuous use of VDU, the overall blinking frequency got reduced from 18 to 4 blinks approximately. The same study however, also revealed that VDU exposure did not substantially alter the overall stability of the corneoscleral tear film (Patel, Henderson, Bradley, Galloway, & Hunter, 1991). These VDU-associated changes are largely considered to be a part of a broader term, i.e., computer vision disorder (CVD).
Role of Blue Light Exposure
Interestingly, blue light, which is emitted from the screens of digital devices, has been found to precipitate degeneration of the corneal epithelial cells. This is mediated by an active generation of the reactive oxygen species (ROS) which becomes maximum during exposure to the blue spectrum of visible light (Xu, Qu, Chen, & Zhang, 2018). An increased inflammation of the corneal surface is also accompanied by an overstimulation of proinflammatory cytokines which can be potentially counterbalanced by means of anti-inflammatory factors such as nerve growth factor (Mehra & Galor, 2020).
Preventive strategies for Dry Eye due to VDU
There exists a set of tips regarding lifestyle modulation which can be adopted to prevent dry eye associated with VDU. Some useful methods are described below (Mehra & Galor, 2020):
1.A simple exercise with repetitive blinking of eyes can be used to ensure the sustainability of tear film.
2.VDU must be placed at a distance of at least 90 cm from the viewer.
3.The viewer’s gaze should be directed downwards at an angle of 10° or more.
A persistently severe complaint of dry eyes warrants treatment with artificial tears or other corneal lubricating agents. Furthermore, anti-inflammatory ointments or antibiotics can also be applied for a concomitant corneal or conjunctival infection.
- Dry eye. Retrieved from https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/dry-eye?sso=y
- Mehra, D., & Galor, A. (2020). Digital Screen Use and Dry Eye: A Review. The Asia-Pacific Journal of Ophthalmology, 9(6), 491-497. doi:10.1097/apo.0000000000000328
- Patel, S., Henderson, R., Bradley, L., Galloway, B., & Hunter, L. (1991). Effect of Visual Display Unit Use on Blink Rate and Tear Stability. Optometry and vision science : official publication of the American Academy of Optometry, 68, 888-892. doi:10.1097/00006324-199111000-00010
- Xu, W. H., Qu, J. Y., Chen, Y. L., & Zhang, M. C. (2018). [Influence of blue light from visual display terminals on human ocular surface]. Zhonghua Yan Ke Za Zhi, 54(6), 426-431. doi:10.3760/cma.j.issn.0412-4081.2018.06.008