Some of the most common causes of vision loss in dogs include:
Since the position of dogs eyes are generally on the side of their head, they do excel at having a better overall peripheral vision in comparison to humans. Their peripheral vision is generally around 250 degrees in comparison to humans who have 190 degrees field of vision.
The poor luck of the draw is not over for canines! They have much worse sight than humans. According to the Psychology Today, dog’s vision is only 20/75 in comparison to the human standard of 20/20. To put this into context, someone with 20/75 vision can see a tree clearly 20 feet away. Compare that with a person who has 20/20 vision, they can see the same tree clearly from 75 feet away. Let’s just say that dogs should not be acquiring their driver’s licenses anytime soon as they are way below the required standard!
The ladybug doesn’t look so beautiful now without its dashing red! Researchers are still on the fence about this but the majority of current scientists believe this is what dogs actually see.
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Dogs indeed see colour but… they are red-green colour blind! The reason being that dogs only have two types of cones (colour receptor cells) in their eyes whereas humans typically have 3 kinds of cones. For humans, the cones come in three colours – red, green and blue-violet which covers the entire colour spectrum. For dogs, the cones come in two colours: blue and yellow. This causes them to have dichromatic colour vision which is similar to people who are red-green colour blind. What does this mean exactly? Let’s first explain how the eye visualises colour. To detect coloured light, the eye relies on neurons which are located inside the eye’s retina. When light is detected on the cones inside the retina, the neuron’s activity changes depending on the colour of the light. For example, if the light is yellow, the neurons become active. If the light is blue, the neurons are suppressed. The neuron signals are sent to the brain for interpretation and as a result, the relevant colour can be visualised. For dogs, their two kinds of cones means they are limited to only distinguishing between blue and yellow light. If the light is red or green, this has no effect on the neurons in the eye. This causes no signal to be sent to the brain to clarify the colour. Therefore, as research points out, the colours would in fact appear gray instead of red or green. Although, some scientists point out that a dogs brain may in fact give those colours they cannot see a different one (apart from gray)!! Hopefully further study will figure out the truth.
Somewhere around 1 month of age, your little fur balls sight should be well enough developed that he’ll be able to see something and walk toward it, whereas earlier he had to listen and feel for what he wanted. Objects become more defined rather than still appear as unrecognizable blobs. Even though your puppy’s eyesight will continue to improve throughout the first several weeks of his life, his vision may never be as clear as yours is.
When a puppy’s eyes start to peel open, you’ll know his eyesight development is in the beginning stage. Usually you’ll see his eyes glistening through the lids around 2 weeks of age, according to Cesar Millans website, Cesar’s Way. The eyes may not open fully until the dog is closer to 4 weeks old. Even though his eyes are slightly open during this stage of development, he doesn’t have clear vision yet. His sight will be limited and blurry in the beginning as his eyes continue to develop.
When you go to the eye doctor, you have to cover one eye and read a line of numbers. If you can clearly see a certain row at a distance of 20 feet, then you have perfect vision of 20/20. Inability to read lower rows indicates your vision is less than perfect, say 20/40 or 20/60. Dogs can’t read numbers and letters, so a veterinary eye specialist uses black-and-white grids to determine if your pooch can detect a pattern. Some of the best field-of-vision tests on dogs are equivalent to a 20/75 for a human, explains Dr. Stanley Coren, a psychologist specializing in vision, hearing and neuropsychology. Don’t worry about it; dogs don’t rely on eyesight as humans do. Your puppy’s nose is his greatest asset; his sense of smell is his guide for getting around.
Melodie Anne Coffman specializes in overall wellness, with particular interests in womens health and personal defense. She holds a masters degree in food science and human nutrition and is a certified instructor through the NRA. Coffman is pursuing her personal trainer certification in 2015.
Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.