The only known hereditary eye condition known in Bedlington Terriers is Total retinal dysplasia (TRD). It is a RARE condition associated with detachment of the retina (which receives light in the back of the eye). Puppies are blind from birth.
At 3 to 4 weeks of age, the breeder may notice that affected pups are less active and frequently bump into objects.
A vet will be best able to examine the pup's eyes for this condition with an ophthalmoscope at 12 to 16 weeks of age, when the retina is mature, but it should be obvious at a puppy check at 8 weeks old that there is a severe eye condition present. There may be a white pupil, because the detached retina is immediately behind the lens. There may be haemorrhage in the eye.
No treatment is possible so all breeding stock should be eye tested, but as the signs are so severe it should be obvious if the Bedlington is blind. A recessive gene is responsible for TRD so 2 normal looking parents can produce affected puppies if they are carriers. The parents should not be bred from again and investigations should be carried out into related dogs, which may also be carriers.