All About That Blink

Blink frequency has become an area of focus in recent years, and has been especially prevalent regarding discussions of digital screen use and visually demanding near tasks.^1,2 Specifically, studies have shown that blink rate decreases with increased visual demands during near tasks, such as computer use, virtual meetings, and reading.^1,2

However, it is important to also consider blink quality. For example, is the blink complete or incomplete? Is that muscular contraction stimulating the muscles of Riolan, thus releasing and distributing an adequate amount of meibum onto the ocular surface? Is the corneal epithelium healthy enough to withstand the friction created by the interactions between these tissues? Evaluating such aspects of blink quality—beyond simply assessing blink rate—can provide valuable insights into the ocular symptoms your patients may be experiencing.

BLINK BREAKDOWN

Blinking is a complex neuromuscular reaction. The downward movement of the upper eyelid results from neural inhibition of the levator palpebrae muscle, with simultaneous activation and contraction of the orbicularis oculi muscle.¹ Once this deactivation/activation is complete, the opposite reaction is needed to relax the orbicularis and elevate the upper lid by activating the levator.¹ Any dysregulation, disorganization, or inhibition of these complex neural feedback systems could lead to dysfunction and pathology of the ocular surface (Figure).

Infrequent and/or incomplete blinking may be to blame for eye strain syndromes, including computer vision syndrome. One study showed that symptoms of computer vision syndrome were greatest in participants who exhibited the lowest blink rates and the highest percentage of incomplete blinks.² The authors also noted that quantity was not an adequate solution; in other words, simply instructing participants to blink more frequently did not reduce their symptoms significantly and may also have impaired their ability to perform tasks.²

Another study demonstrated that incomplete blinking was associated with a two-fold increase in the risk of dry eye disease.¹ It may be an independent risk factor for evaporative dry eye, as participants with incomplete blinking had significantly more meibomian gland dropout, poorer meibum quality, and lower lipid layer thickness.¹ Interestingly, no correlations were found between the quantity of blinking and any of these measures of ocular surface health.¹

LEARNING MORE EACH DAY

When it comes to our understanding of the dynamics of the tear film and ocular surface disease, we simply don’t know what we don’t know. Continuing to analyze our patients’ blink patterns with regard to the quantity and quality of the blinking process will lead to a more complete understanding of this important tear film rejuvenator.