Thursday, December 27, 2012

Snow Blindness

Looking out upon the white snowy landscape resulting from winter storm Euclid, I got to thinking about snow blindness. Can the average person get snow blindness? What is it? Is it permanent? 

Snow blindness, or sunburn of the eye's surface, happens at high altitudes where incoming ultraviolet rays reflect off snow to burn the corneas of unprotected eyes. Like sunburn, the problem isn't noticed until hours later when eyes are teary or bloodshot. With severe exposures, eyes feel gritty and may swell shut. Fortunately, corneas usually heal in 12 - 48 hours and painful snow blindness rarely causes permanent eye damage. 

Bottom line = wear winter eye protection (especially in high altitudes) and enjoy the snow! It's my favorite time of the year.

Thursday, December 20, 2012

Pupillometry - The Eyes Have It

Since I spend a lot more time in the dark looking at holiday displays in December than other months, it got me thinking about the way our pupils open and close.

This is called pupillometry and it isn't just limited to adjustments to light. Pupils also dilate when a person is anxious, excited, and working on math problems! 

In fact, the pupil serves as a sensitive indicator of cognitive, emotional, and sensory responses in psychological research. The eyes really do serve as windows to the soul or at least the brain. For more details on pupillometry, check it out.  

Friday, December 7, 2012

Twinkling Lights

In many countries, December is a time of twinkling lights, holiday decorations, and good cheer. Some city displays seem to challenge the night sky.

I have to admit, I love holiday lights especially the white ones. Even knowing about wavelengths, the way light travels, and all the rest of the science doesn't dim the magical feeling that a light display offers after dark.

Ever wonder how those lights would look on a large scale? A NASA-NOAA satellite gives us a much broader view of the Earth at night. Check it out.  

Earth at night