Retinal Detachment and Hemorrhages

March 7, 2020

Retinal detachment a separation of the neurosensory retina by expansion of the potential space that exists between it and the retinal pigmented epithelium (RPE).  Retinal hemorrhage describes blood within or pooled in front of or behind the retina

Anatomy/Physiology

Retinal detachments can form by three mechanisms: 1) accumulation of fluid or cells  beneath the neurosensory retina (exudative detachments); 2) a hole or tear in the retina that permits liquified vitreous to percolate into the subretinal space (rhegmatogenous detachment; and 3) traction on the retina by organizing vitreous membranes (tractional detachment)

Retinal hemorrhages are formed when blood is liberated from the retinal or choroidal vessels, which can occur from vessel rupture, vessel leakage and/or poor clotting ability.

Clinical Signs

Loss of vision is the major sign of retinal detachment, but occurs only when are large area of the retina is affected and is difficult to routinely detect in patients with normal vision in the contralateral eye.  In cases of complete detachment, the retina can become displaced forward and may be visualized through the pupil in contact with the back of the lens.  With long-term detachment, increased iris new blood vessels can form on the iris and contribute to spontaneous hyphema and neovascular glaucoma.

Causes

Causes of retinal detachment are numerous and include high blood pressure, breed-predisposition, intraocular surgery, intraocular inflammation, systemic infections, immune-mediated conditions, cancer, trauma, and congenital eye malformations.

Causes of hypertension include hyperadrenocorticism, hyperthyroidism, kidney failure, diabetes mellitus and tumors.

Systemic infections include fungal, tick-borne, protozoal and bacterial organisms.

Breeds predisposed to detachment include Bichon Frise, Shih Tzu, Miniature Poodle, and Labrador Retriever, among others.

Causes of retinal hemorrhage include high blood pressure, decreased blood platelets, decreased clotting factors, diabetes mellitus and cancer.

Examination

The retina is examined by indirect and/or direct ophthalmoscopy.  A complete retinal exam requires pupil dilation, although this is not possible or advised in select cases.  We evaluate for retinal tears, hemorrhages or inflammation; the appearance of the detachment guides diagnosis of the cause.  Screening lab work and/or tests for specific diseases may be needed.  If hypertension is suspected, blood pressure will be measured.  Blood pressure is measured in dogs and cats similar to how it is measured in people, with the cuff placed on a shaved region of a limb or the tail.

Treatment

For both retinal detachment and retinal hemorrhages, treatment of the underlying disease is most important.  For many causes, this results in resolution of the detachment.  In cases of breed or surgery-related detachments where a tear is present, retinal reattachment surgery may be indicated.

Monitoring

Regular rechecks are needed to assess retinal reattachment in response to therapy.  If systemic disease is present, we will partner with your regular veterinarian and/or other specialists involved in your pet’s care.

Surgery

For small detachments that only need laser surgery to prevent progression, it can be performed at this hospital.  Retinal reattachment surgery is a highly specialized procedure and performed by only a handful of veterinary ophthalmologists in the country.  The surgery involves entering the eye to break down attachments between the retina and vitreous, repositioning the retina and then securing the retina in place with laser.  This procedure is not performed at Northwest Animal Eye Specialists, but we refer cases that would benefit from surgery to a hospital that provides it.

Prognosis

Prognosis for vision depends on the underlying cause, duration of detachment, response to treatment and concurrent ophthalmic disease.  Even extensive detachments have the potential to reattach with return of vision.  With retinal tears, prognosis depends on time from detachment until surgery, with duration of 4 weeks generally cited as the maximal amount of time for a reasonable prognosis for vision to be considered.