This defect is a congenital (i.e. present at birth), inherited, bilateral eye disease of some breeds of dogs, which affects several different components of the eye, including the retina, choroid, optic disc and sclera, to varying degrees. It can be a mild disease, or severely affected dogs may be blind.
CEA is caused by a simple autosomal recessive gene defect, and unfortunately, there is no treatment for it.
Animation of sectional anatomy of the eye:
Fundus and retinal role:
Which breeds are affected?
The main breeds affected are:
- Collies (Smooth- and Rough-coated),
- Shetland Sheepdog
- Australian Shepherd
- Border Collie
The frequency of occurrence is highest in Collies (in which breed in the US, the incidence has been estimated to be as high as 80-85%) and Shetland Sheepdogs, and lower in other affected breeds.
How is CEA diagnosed by my veterinarian?
Through a comprehensive eye examination, including looking at the back of the eye with an ophthalmoscope, your veterinarian will classify CEA with the following grading system:
- Stage 1: Hypoplasia /dysplasia is present in the choroid
- Stage 2: Hypoplasia /dysplasia, plus a 'hole' in the choroid (coloboma)
- Stage 3: Same as stage 2, but with associated retinal detachment
- Stage 4: Same as stage 3, but complicated by intraocular bleeding
What damage does CEA cause?
Four specific circumstances are observed in CEA.
Picture of a normal dog fundus:
-Hypoplasia / dysplasia of the choroid:
This is an invariably present abnormality of the condition. It is a non-progressive lesion, bilateral , sometimes symmetrical. It appears first during gestation. On ophthalmological examination, it appears as a light area in the back of the eye, with fewer, and abnormal, blood vessels (hypoplasia and dysplasia). A decrease in pigmentation is also evident.
Image of choroidal dysplasia:
-Coloboma (or 'hole') in the choroid, or occasionally in the iris
-Complete or partial detachment of the retina
This congenital detachment is often associated with 'strabismus', a condition where the eyes do not properly align with each other, which may interfere with binocular vision. Retinal detachment may be partial or total and cause blindness .
Image of a retinal detachment :
- Intraocular hemorrhage: An independently exacerbating feature.
What is the prognosis of CEA?
In dogs with stages 1 and 2, the effects on vision are absent or insignificant clinically in 95% of cases. However, extensive lesions of choroidal hypoplasia associated with a large coloboma can cause blindness.
In stages 3 or 4, blindness is more common than not. Nevertheless, it would be unusual that the infringement is bilateral, so oftentimes satisfactory vision in the other eye allows compensation, and adequate sight.
If you have questions and you'd like to reach out to us, you can call us directly at (925) 744-6421, or you can email us at [email protected].