My pet has been diagnosed with Retinal Detachment – what is the Retina?
The retina is a like a thin film layer lining the back of the eye made up of photoreceptors, (light-sensitive cells) and other processing cells whose job is to convert a light to an electrical signal so that it can be transmitted to the brain. Retinal detachment is the process whereby the layer of light sensitive cells peels off the back of the eye and comes to float around freely. Detachments can be partial (where only a bit of the retina or multiple small areas detach) or total (when the whole retina comes off).
Signs of retinal detachment
The most common sign of retinal detachment in a pet is blindness, or some level of vision loss. Whether the animal is completely blind will depend on whether there is a total or a partial detachment, and whether just one or both eyes are affected. Other possible signs of retinal detachment are dilated (large) pupils, bleeding into the eye, or a whitish/pink appearance inside the eye behind the lens.
Causes of Retinal Detachment
There are many potential causes of retinal detachment. They can be divided into eye-related causes (usually only affecting one eye), and systemic (or rest-of –the-body) causes which generally affect both eyes at the same time. Eye-related causes include congential problems (ie ones a dog has been born with, like Collie Eye Anomaly, or Retinal Dysplasia),trauma, uveitis (inflammation inside the eye), glaucoma and intra-ocular tumours. Systemic causes include infectious diseases, certain types of cancer, high blood pressure and immune-mediated (where the pet’s immune system inappropriately attacks the retina). In older cats the most likely cause of retinal detachment is elevated blood pressure.
How Do We Diagnose a Detached Retina?
Retinal detachments can usually be seen when a veterinary ophthalmologist examines the back of the eye with an instrument called an ophthalmoscope. If the front of the eye is too opaque for us to see into (for instance after a trauma, when the eye is full of blood) then we may confirm the diagnosis by an ocular ultrasound. This is a non-invasive procedure which in most cases can be performed with the pet awake.
Can Detached Retinas be Treated?
Depending upon the cause of the detached retina treatment may be possible. For most eye-related causes, re-attachment is not possible, but if it has been caused by high blood pressure for instance, then treatment to reduce the blood pressure may lead to reattachment of the retina, and if achieved quickly enough, this may restore some vision. In immune-mediated causes of retinal detachment, treatment with immunosuppressive medication, can likewise sometimes result in re-attachment of the retina. Very occasionally (for instance if the detachment has occurred following intra-ocular surgery) the pet may be a suitable candidate for surgical re-attachment of the retina, which is a procedure in its infancy in dogs in the UK. If your dog is potentially a suitable candidate for this procedure, your veterinary ophthalmologist will offer you this option.
What If My Pet’s Retinal Detachment Cannot Be treated?
In many instances unfortunately the detached retina cannot be treated. This means that in these cases the pet will remain permanently bind in one/ both eyes. Providing certain allowances are made for them, most pets will adapt very well to their blind condition, after an initial adjustment period. Retinal detachments are not painful in themselves, so most pets can live very happily with a detached retina. However in some cases the pressure in the eye may go up several months or years after retinal detachment (a condition called secondary glaucoma) and in these cases the eye becomes very painful and its removal is recommended. It is therefore advised that all pets with a retinal detachment have their eye pressure checked every 4-6 months, or sooner if there is any change in appearance of the eye or signs of discomfort.