This may ocur in a tiny area, or throughout the entire retina. Areas of detachment will cause blind spots. Dogs with severe retino-vascular abnormalities are more prone to detachment and hemorrhage, especially if they receive a kick to the head while working stock, or their blood pressure rises during strenous work in hot weather. This particular defectis found most commonly in dogs with long, narrow show Collie type heads, though not always. It occurs in adult animal, often after stress.
Opaque spots appear on the surface of the cornea, possibly due to restricted blood flow.
CEA is a polygenic recessive trait and it is likely caused my several gene pairs. It doesn't follow the simple Mendelian ratios. Test breedings of affected to nonaffected have not proven successful in establishing whether an individual dog is clear. Then do NOT breed for either parent or littermates. You cannot tell who carries the genes or who does not.