Canine cataracts are a prevalent cause of visual loss in dogs, frequently resulting in blindness. Cataracts typically occur when proteins break down in the lens of a dog's eye and clump together, obstructing the passage of light. [1] [2] There are several reasons cataracts may occur in dogs, such as heredity, trauma, aging, diabetes, glaucoma, and progressive retinal atrophy.
Cataracts can be genetic, existing in breeds who are predisposed to developing them. Canine diabetes is another common cause of canine cataracts, due to the increased concentration of glucose in the lens, which swells the lens. A third prevalent cause of canine cataracts is developmental, in which certain embryological conditions, like toxins or infections, cause cataracts present at birth. [3]
Veterinarians use a common classification system to assess a patient’s suitability for cataract surgery and to inform of potential treatment options. A cataract may not progress through all the stages.
An incipient cataract involves a small area of the lens and vision is impacted to a small degree. An immature cataract involves around 10-99% impact on the lens, with variable vision impacts. A mature cataract involves a lens that is totally impacted, with full vision loss. Finally, a hypermature or Morganian cataract involves the liquification of the lens protein, causing a crystallized appearance in the eye. A cataract at this stage may risk retinal detachment, where the retina begins to detach from the back of the eye. [4]
Additionally, cataracts are categorized by their age of onset, depending on whether the canine developed cataracts congenitally, as a juvenile, or as a senior. [4]
Currently, the only method to successfully remove a cataract and restore vision is through surgery. [3]
Some cataracts, like incipient cataracts, affect vision to a small degree and do not always warrant surgery. However, continuous monitoring of any progression is necessary to assess the possibility of further treatment. When a cataract is deemed likely to progress, treatment is then recommended. [3]
Canine cataract surgery involves small incisions in the cornea. The process is more intensive than in human cataract surgery, mainly due to the larger lens area in dogs than in humans which requires more power to break up the cataract, the need for general anesthesia, and post-operative care that involves anti-inflammatory medication and eye drops. Finally, unlike humans, the corneal incisions do not self seal, so they must be sutured after the surgery. Success rates for canine cataract surgery are around 80-95%, but this is variable on the breed of dog and the cataract classification. [3]
Diabetic retinopathy, is a medical condition in which damage occurs to the retina due to diabetes. It is a leading cause of blindness in developed countries.
A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or double vision, halos around light, trouble with bright lights, and difficulty seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression. Cataracts cause 51% of all cases of blindness and 33% of visual impairment worldwide.
The Samoyed is a breed of medium-sized herding dogs with thick, white, double-layer coats. They are spitz-type dogs which take their name from the Samoyedic peoples of Siberia. Descending from the Nenets Herding Laika, they are domesticated animals that assist in herding, hunting, protection and sled-pulling.
The Australian Shepherd is a breed of herding dog from the United States. The name of the breed is technically a misnomer, as it was developed in California in the 19th century. It is believe to have its origins in sheepdog breeds from northwest Spain, as well as collies imported, alongside sheep, from Australia and New Zealand; the breed reportedly took its name from this trade. Originally used solely as a herding dog, the Australian Shepherd has become one of the most popular companion dog breeds in North America.
Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye and causes it to thicken and swell (edema). The swelling may distort a person's central vision, because the macula holds tightly packed cones that provide sharp, clear, central vision to enable a person to see detail, form, and color that is directly in the centre of the field of view.
Eye surgery, also known as ophthalmic surgery or ocular surgery, is surgery performed on the eye or its adnexa. Eye surgery is part of ophthalmology and is performed by an ophthalmologist or eye surgeon. The eye is a fragile organ, and requires due care before, during, and after a surgical procedure to minimize or prevent further damage. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient, and for taking the necessary safety precautions. Mentions of eye surgery can be found in several ancient texts dating back as early as 1800 BC, with cataract treatment starting in the fifth century BC. It continues to be a widely practiced class of surgery, with various techniques having been developed for treating eye problems.
Phacoemulsification is a cataract surgery method in which the internal lens of the eye which has developed a cataract is emulsified with the tip of an ultrasonic handpiece and aspirated from the eye. Aspirated fluids are replaced with irrigation of balanced salt solution to maintain the volume of the anterior chamber during the procedure. This procedure minimises the incision size and reduces the recovery time and risk of surgery induced astigmatism.
This is a partial list of human eye diseases and disorders.
Cataract surgery, also called lens replacement surgery, is the removal of the natural lens of the eye that has developed a cataract, an opaque or cloudy area. The eye's natural lens is usually replaced with an artificial intraocular lens (IOL) implant.
The Lions Eye Institute (LEI) is an Australian medical research institute affiliated with the University of Western Australia. It was established in 1983 with support of the Lions Clubs of Western Australia and headquartered in the Perth suburb of Nedlands, Western Australia. The LEI is a not-for-profit centre of excellence that combines an ophthalmic clinic with scientific discovery developing techniques for the prevention of blindness and the reduction of pain from blinding eye conditions.
The health of dogs is a well studied area in veterinary medicine.
Progressive retinal atrophy (PRA) is a group of genetic diseases seen in certain breeds of dogs and, more rarely, cats. Similar to retinitis pigmentosa in humans, it is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait, with the exception of the Siberian Husky (inherited as an X chromosome linked trait) and the Bullmastiff (inherited as an autosomal dominant trait). There is no treatment.
Sudden acquired retinal degeneration syndrome (SARDS) is a disease in dogs causing sudden blindness. It can occur in any breed, but female dogs may be predisposed. Approximately 4000 cases are seen in the United States annually.
Veterinary surgery is surgery performed on non-human animals by veterinarians, whereby the procedures fall into three broad categories: orthopaedics, soft tissue surgery, and neurosurgery. Advanced surgical procedures such as joint replacement, fracture repair, stabilization of cranial cruciate ligament deficiency, oncologic (cancer) surgery, herniated disc treatment, complicated gastrointestinal or urogenital procedures, kidney transplant, skin grafts, complicated wound management, and minimally invasive procedures are performed by veterinary surgeons. Most general practice veterinarians perform routine surgeries such as neuters and minor mass excisions; some also perform additional procedures.
Cancer is the leading cause of death in dogs. It is estimated that 1 in 3 domestic dogs will develop cancer, which is the same incidence of cancer among humans. Dogs can develop a variety of cancers and most are very similar to those found in humans. Dogs can develop carcinomas of epithelial cells and organs, sarcomas of connective tissues and bones, and lymphomas or leukemias of the circulatory system. Selective breeding of dogs has led certain pure-bred breeds to be at high-risk for specific kinds of cancer.
Canine glaucoma refers to a group of diseases in dogs that affect the optic nerve and involve a loss of retinal ganglion cells in a characteristic pattern. An intraocular pressure greater than 22 mmHg (2.9 kPa) is a significant risk factor for the development of glaucoma. Untreated glaucoma in dogs leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness.
Diabetes mellitus is a disease in which the beta cells of the endocrine pancreas either stop producing insulin or can no longer produce it in enough quantity for the body's needs. The disease can affect humans as well as animals such as dogs.
Congenital cataracts are a lens opacity that is present at birth. Congenital cataracts occur in a broad range of severity. Some lens opacities do not progress and are visually insignificant, others can produce profound visual impairment.
Phacolytic glaucoma (PG) is a form of glaucoma which is caused due to a leaking mature or immature cataract. Inflammatory glaucoma which occurs in phacolysis is a condition which is a result of the leakage of protein within the lens into the capsule of a mature or hyper mature cataract and involves a simple procedure to be cured that is referred to as cataract extraction.
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