Doggy Vision

The bond between people and their dogs is a special one.  At some point you’ve probably wondered:  What does my dog see?  

Dogs’ retinas have light sensing cells similar to ours: rods for differentiating light and dark and cones to distinguish color and fine detail.  Dog retinas are mostly made of rods giving them the ability to see very well in the dark and also excellent motion detection.  However dog retinas only have about a tenth of the amount of cones that we have in our eyes.  While they do see in color it is a limited color spectrum similar to a red-green colorblind human.  Dogs see in shades of yellow and blue, and don’t see green, yellow, orange, and red as we do.  Dogs also have worse visual acuity than humans, about 20/75.  So what you can just make out at 75 feet a dog would need to be 20 feet away to see.  Some dogs such as guide dogs are bred to have better visual acuity which is closer to that of a human however.  
However dogs can see some of the UV spectrum that we cannot.  Interestingly urine trails become visible in UV light and we all know that dogs like to check out urine.  You probably thought they could only smell it!  
This ability to see UV light makes wild dogs better predators because not only can they track their prey through urine but they can also more easily see prey which have a similar color to their environment, like a contrast enhancement.
Another major difference between dog and human vision is peripheral vision and depth perception.  A dogs eyes are angled outward where as our eyes essentially both point forward.  This gives dogs an increased field of view in their peripheral, but at the expense of a decrease in binocular field of view which is what allows for depth perception.  Dogs can see wider than us, but we can perceive depth better for more of our field of view.
Of course we all know that dogs’ true strength is not their sight.  While they can see with their eyes, they can really “see” through smell and hearing.  Dogs’ noses are 1000+ times more sensitive than our noses are.  Also while dogs lack the visual acuity that we have, they make up for it by observing other visual cues such as movement.  For example one of the strongest signals from us that dogs will read is our body language.  They can easily tell if we are acting friendly or strange and threatening or if we are being stern and dominate or a pushover.
Has it been 2 years since your last eye exam?  You need to get a checkup!  Dr. Andrew Benson of VCC Eye Care is open for exams at Sports Optical in Denver.  Please call us at 303-455-3369 or email to schedule your exam. 
Wanna get your dog seeing well with some prescription doggles?  You know it doesn’t see so great!  We were thinking about making prescription goggles for dogs…

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