By Emily Sohn. June 26, at pm. But there are children of certain tribes in Asia who are distinctly fishlike.
Called sea gypsies, these island-dwelling people are famous for their swimming and diving skills. A study now shows that sea-gypsy children spend so much time swimming that their eyes have adapted especially well to seeing clearly underwater. Method 1. See the inside of your swimming pool. It sounds simple, but anyone who's tried it knows the sting that accompanies opening your eyes in a heavily chlorinated pool.
Luckily, there are techniques available to acclimate your land-lubber's eyes to the water. If those techniques don't prove satisfactory, however, it's recommended you turn to goggles or dive masks as a tool to safely see in the pool.
Practice at home by filling your sink or bathtub with water, plugging your nose, submerging your face, and then opening your eyes. Starting with water sources free of chlorine or debris will help you get use to the feeling of water on your eye, without additional discomfort. Chlorinated pools are generally kept at a safe-for-swimming pH level of 7. This effectively kills bacteria, but not the various fats and oils we bring into the pool; these accumulated bodily byproducts are common eye irritants.
While exposure to normal amounts of chlorine is irritating, it will not cause permanent damage. It will, however, wash the protective tear film away from your cornea, actually making the eye more vulnerable to any bacteria which has survived the chlorinated pool. Open your eyes in the open ocean.
Near the shore, waves are constantly throwing sand and small rocks toward the beach, making corneal scratches from debris a possibility. Away from the shore, you'll have a more pleasant experience looking around underwater. Careful about opening that mouth, too—while they're not all as strictly harmful as they may sound, one gulp of seawater can contain millions of bacterial cells, tens of thousands of zooplankton, and hundreds of thousands of phytoplankton.
Look under a lake. Bacteria is your major concern when opening your eyes in a freshwater lake. While it's far from a given that you'll have problems with the lake's single-cell citizens, it's recommended you use eye protection goggles or a dive mask when you want to see underwater. In shallower water, dirt and other hazardous particles from the lakebed can be kicked up while swimming and enter your eye. Acanthamoeba is one particular nasty amoeba that can be found in fresh water including, rarely, tap water.
Infection can necessitate a cornea transplant. If you're willing to risk it, you can probably keep your eyes open longer here than in any other body of water!
The dismal visibility in a lake, however, might not provide too much to see. Take your contacts out. In any of the above-mentioned environments, you'll want to remove your contact lenses before opening your eyes underwater. Although it's a bit of a risk for the lenses to float away thought the water pressure will likely keep them in place , the greater danger is bacterial infection.
Wearing a dive mask is a much safer alternative for seeing what's underwater than opening one's eyes, and is optimal for anyone who would be unable to see very well without their glasses. Method 2. Strap on some goggles. Goggles allow you to see clearly underwater without irritation, and their strap ensures they remain affixed to your head while swimming. They're secured easily: you place the lenses over your eyes, and then stretch the silicone strap around to the back of your head.
The strap should press snugly against your temples, like glasses, but shouldn't hurt. A pair of goggles is only as good as its seal, so if water's getting into your lenses you might want to try a different pair. The strap and lens shape should do all the work necessary for a good seal; you shouldn't have to repeatedly fix the suction by pressing them against your eye sockets.
Goggles are uniformly used by competitive swimmers, who can't have their vision compromised by going without, or their speed compromised by using the less aerodynamic dive mask.
Each time they dived down, the lines would get thinner, making the task harder. It turned out that the Moken children were able to see twice as well as European children who performed the same experiment at a later date. What was going on? To see clearly above land, you need to be able to refract light that enters the eye onto the retina. The retina sits at the back of the eye and contains specialised cells, which convert the light signals into electrical signals that the brain interprets as images.
Light is refracted when it enters the human eye because the outer cornea contains water, which makes it slightly denser than the air outside the eye. An internal lens refracts the light even further.
With training, the unique vision of the Moken children might be accessible to any young person Credit: Alamy. When the eye is immersed in water, which has about the same density as the cornea, we lose the refractive power of the cornea, which is why the image becomes severely blurred.
Gislen figured that in order for the Moken children to see clearly underwater, they must have either picked up some adaption that fundamentally changed the way their eyes worked, or they had learned to use their eyes differently under water. A simple eye test proved this to be true — the Moken children could see just as well above water as European children of a similar age.
It had to be some kind of manipulation of the eye itself, thought Gislen. There are two ways in which you can theoretically improve your vision underwater.
You can change the shape of the lens — which is called accommodation — or you can make the pupil smaller, thereby increasing the depth of field. This site contains links to Third-Party or Contractor websites. VSP does not endorse and is not responsible for the privacy practices of Third-Party or Contractor sites. Visitors should review the privacy policy of these sites to understand how they collect and use the information on their sites. VSP's security software is the industry standard and among the best software available today for secure transactions.
Some features, such as VSP's Network Doctor Directory and the member's benefit information, relate directly to a member's personal information. Email subscription information that VSP collects may be used to personalize and target content of the emails you receive from VSP, enabling us to improve our service to you. We may provide general reports on email subscription usage but we will not share email addresses or any personal information that allows for identification of individuals except as described herein.
Text and data charges may apply. Please check with your carrier. You can cancel mobile text messages any time by replying STOP to any message. Personal information collected and how it is used: VSP collects anonymous, non-personal information about users of this site through temporary session cookies. Cookies are small, alphanumeric identifiers that are transferred to a computer's hard drive through the user's Web browser, which enables VSP's systems to recognize the browser and provide personalized features.
Session cookies expire when you close your browser. VSP will collect data about the user's activities that do not personally or directly identify the user when visiting our website. This information may include the content the user views, the date and time that the user views this content, the products the user purchases, or the user's location information associated with the user's IP address.
We do not collect personal identifying information about a user, will not link to any protected health information, and will not target ads to a user based on sensitive health data. In addition, VSP uses technologies such as cookies and pixels to keep track of your activities on our website and the websites of our third-party advertising companies "our Advertising Partners" , and may use those cookies to serve you more relevant advertisements.
We and our Advertising Partners' sites use session cookies and persistent cookies to make it easier for you to navigate and enhance the experience of our site, and to monitor and evaluate our website's operation and use. Any data used to serve targeted advertisements is de—identified and is not used to personally or directly identify a user.
We require third-parties, including Publishers, to provide notice and obtain appropriate consent, where required by applicable law.
How it is transferred to third-party companies: VSP may work with Advertising Partners to help us recognize you and serve relevant advertisements to you when you visit a website or online service in their network. We may also work with Advertising Partners who help us recognize you across different devices in order to show you relevant advertisements.
Our Advertising Partners may collect information about your activities on our website, our Advertisers' websites, and other websites or online services in their networks. We may also work with third-party companies to assist us with website analytics such as evaluating the use and operation of our website so that we can continue to enhance the website and our services. How we use cookies and instructions on opting out of future campaigns: We may use persistent cookies to keep track of your activities when you visit our website, and to serve you relevant advertisements.
Our Advertising Partners may also place persistent cookies on your device when you visit our website or our Advertisers' websites in order to help us recognize you and serve relevant advertisements to you when you visit their website or online service or websites in their networks.
VSP only collects information that does not personally or directly identify you via these cookies. Most browsers can be set to reject all cookies. The Help portion of the toolbar on most browsers will tell a user how to prevent the browser from accepting new cookies, provide notification if new cookies are received, or disable cookies altogether.
Instructions on changing personal information for users : You may have the right to request access to and receive information about the personal information we maintain about you, update and correct inaccuracies in your personal information and have the information blocked or deleted, as appropriate. The right to access personal information may be limited in some circumstances by local law requirements. You also have the right to opt out, free of charge, from the processing of your personal information for marketing purposes.
VSP's website does not direct content to Minors and do not intend to collect personal information from Minors and therefore are not subject to the Children's Online Privacy Protection Act.
VSP responds to emails, electronic messages, and other communications as soon as reasonably practical. VSP's response time shall not exceed any maximum time period that may be specified by law. You agree that you will not use or attempt to use any feature within the Site for any commercial purpose. You agree that you will not use any robot, spider or other automatic device, process or means to access the Site.
Nor shall you use any manual process to monitor or copy our web pages or the content contained thereon or for any other unauthorized purpose without our prior express written permission. You agree that you will not use any device, software or routine that interferes with the proper working of the Site nor shall you attempt to interfere with the proper working of the Site.
You agree that you will not take any action that imposes an unreasonable or disproportionately large load on our infrastructure. You agree that you will not copy, reproduce, alter, modify, create derivative works, or publicly display any content except for your own personal, non-commercial use from the Site without the prior express permission of VSP.
Any illegal or unauthorized use of the Site shall constitute a violation of these Terms of Use.
0コメント