Why is blinking protective

Many different mechanisms work together in our eyes to make blinking what it is. We produce different types of tears, and we have tiny oil glands working around the clock to replenish the protective tear film throughout the day. The Importance of Blinking Do you know how many times you blink in a minute? Blinking Cleans and Replenishes Our Eyes Every blink spreads a thin layer of tears across the cornea of the eye.

All in the Blink of an Eye Many different mechanisms work together in our eyes to make blinking what it is. Palakuru, Jianhua Wang, James V. Aquavella; Effect of Blinking on Tear Dynamics. Optical coherence tomography OCT was used to study the impact of blinking on tear dynamics. One eye of 21 subjects was imaged at the same time of day on two consecutive days.

Dimensional information of the tear film and of the upper and lower tear menisci during normal and delayed blinking were obtained from OCT images using custom software. Digital camera images were used to measure eyelid length and ocular surface area for tear volume estimation. No significant changes in any measured variable occurred between the two repeat visits. For normal blinks, the tear meniscus did not change significantly during blinking or during the open-eye period.

Also for delayed blinks, the height and area of both upper and lower tear menisci significantly increased during the open-eye period. OCT is a promising tool for studying the impact of blinking on tear dynamics. Tear distribution is dynamically balanced and consistent during normal blinking, but it becomes altered during delayed blinking.

Purchase this article with an account. Jump To Subjects and Methods Results Discussion. Palakuru ; Jianhua Wang ; James V. Author Affiliations. Alerts User Alerts. You will receive an email whenever this article is corrected, updated, or cited in the literature.

You can manage this and all other alerts in My Account. This feature is available to authenticated users only. Get Citation Citation. Get Permissions. The tear system is highly dynamic, maintaining balance between tear secretion and tear loss so that the ocular surface is protected while the eye is open. Each blink initiates a cycle of tear secretion, spreading, evaporation, and drainage of tears.

Many studies provide either snapshot information 4 5 6 or averaged performance 5 about the tear system. Real-time videography 4 and video meniscometry 7 imaging have been used to study the lower tear meniscus, and video recorded spectrum analysis 8 has been used to study tear film thickness.

However, only one aspect at a time can be studied using these methods so that the interactions among the different components of the tear system cannot be captured. Using newly developed optical coherence tomography OCT for capturing tear film and tear meniscus images simultaneously, the goal of this study was to determine the effect of blinking on tear dynamics.

Twenty-one subjects 10 women and 11 men, mean age: Informed consent was obtained from each subject, and all were treated in accordance with the tenets of the Declaration of Helsinki. OCT imaging was performed on one randomly selected eye of each subject at the same time of day on two consecutive days. A real-time corneal OCT, developed as described previously, 9 was used to perform vertical mm scans across the central cornea apex including the upper and lower tear menisci simultaneously.

During imaging, the subjects were exposed only to ambient room light and were asked to look at an external target. OCT images were recorded continuously when the subjects blinked normally for three to five blinks.

After the normal blinks, the subjects were asked to delay each blink for as long as possible for another set of three to five blinks. After that, the study eye was given a drop of artificial tears Refresh Liquigel; Allergan, Irvine, CA followed by OCT scanning to obtain true corneal thickness for the calculation of the tear film thickness, as described in detail previously.

Eight OCT images corresponding to a 1-second interval immediately before and after each blink were analyzed for measuring the total corneal thickness. One of these eight images showing upper and lower tear menisci Fig.

Tear film thickness was estimated indirectly by subtracting the true corneal thickness imaged after the instillation of the artificial tears from total corneal thickness obtained at each check point. Results from one interblink interval were obtained since two consecutive blinks formed one interblink interval.

Lengths of upper and lower lids and exposed ocular surface area were measured from the two-dimensional digital images of eyes using custom software after calibration. To use the two-dimensional image to estimate the area of the ocular surface that is curved in the third dimension, a multiplication factor of 1. Total tear volume on the ocular surface was the sum of these volumes.

All formulas are listed in Table 1. The repeatability of the measurements of all variables during both normal and delayed-blinking sessions was estimated as the SD of the differences between repeated measurements between 2 days. Data analysis was conducted on computer Statistica; StatSoft, Inc. The TFT and tear menisci variables obtained during blinks and interblink periods are listed in Table 2 and repeatability results of these measurements are listed in Table 3.

There were no significant differences of TFT between normal and delayed blinks. However, there was a trend toward higher TFTs during the delayed blinks Fig. The averaged thinning rate of TFT was 4. No significant differences in UTMC were found before and after blinks and during the open-eye period for both normal and delayed blinks Fig.

TFV did not change during the normal blinks; however, a significant decrease from 1. Blinking plays an important role in the distribution and drainage of tears and helps in maintaining equilibrium of the tear volume on the ocular surface and in the conjunctival sac. It also plays a critical role in periodic renewal of the preocular tear film. Any alterations in the blinking pattern may affect tear distribution and drainage, leading to changes in the tear volume and other tear system parameters.

McDonald and Brubaker 12 observed nonquantitatively that upper and lower menisci draw fluid from the preocular tear film and swell with time after a blink. Slit lamp photography 13 and video meniscometry 7 14 15 16 have also been used to measure the tear meniscus around the lower eyelid. Savini et al. The upper tear meniscus and tear film cannot be imaged with slowly scanning OCT systems or other methods. These findings may not reflect the impact of a blink and time course after a blink on the dynamic tear system.

Wang et al. The method was validated in repeated measurements of tear distribution on human eyes. It happens involuntarily, but you can also make yourself blink. It takes the average person milliseconds to blink, Pagan-Duran said.

Most people blink somewhere between 10 and 20 times per minute, usually around 15 or 16 times, she added. However, there are some circumstances that make people blink more or less often.

For example, you may blink more frequently if there's something in your eye. Certain conditions, such as an ingrown eyelash, can make it feel like there's something in your eye, which makes you blink more.

Allergies, pink eye and other types of inflammation can also trigger the reflex. Some people have tics, or habitual involuntary movements, that lead them to blink frequently, and stress and anxiety can make you blink more too, according to Pagan-Duran. If you have uncorrected vision problems, you may blink more often because your eyes are naturally trying to correct the blurry vision.

If there is damage to the facial nerve, which is responsible for closing the eyelid, a person may blink more slowly or less often, Pagan-Duran said. Fatigue and some medications can cause a similar effect. When you're focusing on something like watching a movie, you may blink less to strengthen your focus.