Eyecare Topics

Introduction GPS is incorporated in many of our daily objects and serve many purposes in our daily navigation. Drivers use GPS when navigating streets, pedestrians use GPS on mobile devices to navigate walking paths, and GPS devices are being used to monitor human and animal movement. In addition, many recreational uses, such as hiking, use GPS to track locations. GPS is defined as “A system of radio-emitting and -receiving satellites used for determining positions on the earth. The orbiting satellites transmit signals that allow a GPS receiver anywhere on earth to calculate its own location through trilateration. Developed and operated by the U.S. Department of Defense, the system is used in navigation, mapping, surveying, and other applications in which precise positioning is necessary.” (ESRI, GIS Dictionary, GPS) Background on GPS For GPS units to properly locate your position, this requires the three components: space segment, control section and user seg...

What is SPF Sunscreen? SPF, or  Sun Protection Factor ,is a measure of how well a sunscreen will protect skin from UVB rays, the kind of radiation that causes sunburn, damages skin, and can contribute to skin cancer. If your skin would normally burn after 10 minutes in the sun, applying an SPF 15 sunscreen would allow you to stay in the sun without burning for approximately 150 minutes (a factor of 15 times longer). This is a rough estimate that depends on skin type, intensity of sunlight and amount of sunscreen used. SPF is actually a measure of protection from amount of UVB exposure and it is not meant to help you determine duration of exposure. For best protection, experts recommend using a minimum SPF sunscreen of 15, applying the proper amount (2mg/cm 2  of skin, or about one ounce for full body coverage), and reapplying every 2 hours. Most people under-apply sunscreens, using ¼ to ½ the amount required. Using half the required amount of sunscreen only provides...