Collie eye anomaly – characteristics
Collie eye anomaly (CEA) is a complex hereditary ocular disorder which is characterized by regional hypoplasia of choroids, the highly vascularized layer of the eye that supplies blood and nutrients to the retina. Occasionally, tortuous retinal vessels and multiple retinal folds are also observed. The clinical symptoms can vary greatly among affected dogs within one breed, between parent and offspring and within a litter. No medical treatment of the disease is available.
CEA is widespread in dogs, with a prevalence of 65–97% for rough and smooth collies, while the prevalence in Border collies is lower. CEA is also recognized in all herding dogs or breeds that are derived from classic herding breeds.
CEA inheritance is autosomal recessive with variable expression and pleomorphism (wide range in the clinical expression of the defect). Some mildly to moderately CEA-affected dogs appear to retain their normal vision function throughout their life. Severely affected individuals, particularly those with colobomas, can develop retinal detachments leading to blindness. In these cases, subretinal and preretinal neovascularization and intraocular haemorrhage can occur.
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