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The retina is a structure in the back of the eye. It is responsible for receiving light through the lens and converting it into electric signals that can be transmitted to the brain and perceived as sensory data. It is quite a complex instrument, and as such, malformations can occur during its development. These are rare problems, but certain factors such as the breed of your dog and certain matters of heredity can affect the likelihood of contracting them.
Retinal dysplasia is a disorder that occurs when the two layers of the retina do not form together in the correct manner during the formation of the fetus. In its mildest form, this causes light accordion-style folding to occur on the inner layer of the retina, which are called "retinal folds". This disorder is not progressive, which means that whatever degree of severity a puppy possesses at birth is as severe as the disease will ever get. [...]
There are many breeds that are prone to excessive tear production just as some breeds are more prone to dry eye conditions and lack of tear production. Either condition can be a direct result of injury, genetic conditions or infections to the eyes that are inhibiting or stimulating the tear gland functioning.
In cases where excessive tearing is noted there are usually both genetic and health factors at work. In breeds such as the Maltese, Miniature Poodle, Yorkshire Terrier, Shar Pei, Pomeranian and American Cocker Spaniel excessive tear formation, also known as epiphora, is very common. In white and light colored dogs the result may be a reddish stain down the muzzle from the eyes, typically known as red yeast stain. In darker colored the dogs the tear stain may be much less noticeable, but there may be a slightly yeasty or dank smell about the head of the dog. [...]
One of the only known dogs to have a condition known as stationary night blindness, the Briard dog of Sweden is now in the cutting edge of DNA testing to determine a specific test to clearly identify carriers, affected dogs and non-affected dogs.
Stationary night blindness is characterized by various degrees of blindness in the Briard dogs that may become progressively more pronounced as the dog matures or may remain relatively constant. This variation can go from slight loss of vision in shadows or dark areas to almost complete blindness even in full light. Since the dog's will have temperament changes when they start to loose their vision this is often the first indication that there is something wrong with the dog. [...]
Several conditions can lead to your cat having eye drainage. The cat will secrete anything from thin and watery, to thick and postulant, and from clear in color to yellowish or greenish. These conditions are caused by inflammation, infections, such as the flu and evasion of viruses. Sometimes it is caused by an inherited gene or a malfunction of the tear glands that cause eye drainage.
The most common condition for the drainage of the eye is called runny eye. Certain breeds of cats are more prone to leaky eyes than others.
[-]Runny eyes can be caused by the over production of tears. Tears are produced normally to keep the lining of the eye moist. The tears then flow into the tear ducts making their way into the nose. But if there is a problem, the tears will spill onto the face and that is how we determine a cat has runny eyes. [...]
It is very common for a veterinarian to see cats coming into her office with red eyes. Red eye may or may not be painful, but cat owners often observe that their cat has been pawing at his eye or face.
Often time there is redness and swelling in the inner eyelid known as the conjunctiva, when this condition occurs it is called chemosis. The cause of chemosis or simply conjunctiva is due to an irritation, a foreign substance that has made its way into the inner eyelid and lodged there. It could be dust or a piece of hair. Any foreign substance would make the eye irritated and inflamed. Occasionally the ulcers can penetrate into deeper areas of the cornea and then your cat is at risk for the ruptures in the eye and causing complete eyesight. [...]
Anterior Segment Dysgenesis, more simply known as ASD, is an inherited, genetic condition that most often occurs in horses that are dark or chocolate brown in color and have a white or cream colored mane and tail. Typically horses with ASD are part of the Rocky Mountain Horse breed, which is the gaited horses bred and developed in the Rocky Mountain area of the United States.
ASD is present at birth and does not become progressively worse with age; rather it remains constant throughout the life of the horse. Screening by a veterinary ophthalmologist when the foal is approximately four months old can confirm the presence or absence of the condition, and foals can then be cleared for breeding stock if the problem is not present at that age. Horses cannot develop ASD as they mature so it is relatively easy to keep affected foals from being produced if owners are diligent with testing before breeding. [...]
Moon blindness in horses has nothing to do with the moon, but historically many people though that the occurrence or reoccurrence of the disease become worse during different phases of the moon, hence the name.
The correct name for moon blindness is equine recurrent uveitis or ERU and is still not fully understood by vets and horse owners. There are several different factors or precursors that can bring on the first episode of moon blindness, often it's relatively mild in nature and may not be problematic for the horse at all. Many times the first episode seems to correct itself, lulling the owner into a false sense of security about the horse's eyes. Every subsequent bout of the disease causes greater damage to the eye and the long term prognosis for horses with ERU is total blindness at some point in time. Since the episodes of moon blindness may occur frequently, within one or two weeks of each other or many only happen once a year or once every several years each horse will have a different progression of the condition. [...]