Blindness

• Cause:
  • Intra-ocular disease (congenital disease (eg retinal dysplasia, collie eye anomaly), corneal opacity, uveitis (numerous causes), cataract, glaucoma, retinal detachment, inherited retinal degeneration, (eg progressive retinal atrophy, retinal pigment epithelial dystrophy), sudden acquired retinal degeneration syndrome (SARDS), dietary deficiency (eg Vitamin E), toxicity (eg ivermectin), intra-ocular neoplasia, intraocular hemorrhage and trauma).
  • Optic nerve disease (optic neuritis, optic nerve or perineural tumor, compression of optic nerve by retrobulbar space occupying lesion).
  • Intracranial disease (congenital disease (eg hydrocephalus), immune-mediated disease (eg GME, neoplasia, toxicity (eg lead), dietary deficiency (eg thiamine), metabolic disease (eg neuronal ceroid lipofuscinosis, lysosomal storage disease, hepatic encephalopathy), infections (eg distemper), consequence of hypoxia, trauma).
• It is important to localize where the lesion is occurring to target appropriate diagnostic procedures.
• Signs: obvious blindness.
• Diagnosis: recognition of blindness, diagnosis of underlying disease.
• Treatment: treat underlying cause where possible.
• Prognosis: variable; occasionally total blindness can be reversible depending on cause. Print off the owner factsheet Living with a blind dog to give to your client.

Acute presentation

• Dog obviously blind, bumping into objects, with or without ocular pain.
• Note that a dog with slowly developing and long-standing blindness will negotiate obstacles so well in a familiar environment that the owner may not notice obvious visual deficits.

Cost considerations

• Investigation of underlying disease may be costly especially if advanced diagnotic techniques are required, eg ERG, CSF, CT and MRI.