Vascular retinopathies
Vascular retinopathies: Excerpt from Professional Guide to Diseases (Eighth Edition)
Vascular retinopathies are noninflammatory retinal disorders that result from interference with the blood supply to the eyes. The five distinct types of vascular retinopathy are central retinal artery occlusion, central retinal vein occlusion, diabetic retinopathy, hypertensive retinopathy, and sickle cell retinopathy.
Causes and incidence
When one of the arteries maintaining blood circulation in the retina becomes obstructed, the diminished blood flow causes visual deficits. (See Anatomy of vascular retinopathy.)
Central retinal artery occlusion may be idiopathic or may result from embolism, atherosclerosis, infection, or conditions that retard blood flow, such as temporal arteritis, carotid occlusion, and heart failure. This occlusion is rare, occurs unilaterally, and usually affects elderly patients. However, if it occurs in a younger person, the obstruction may have originated in the heart (such as embolization from plaque material from valve vegetations) and should be investigated accordingly.
Causes of central retinal vein occlusion include atherosclerosis, hypertension, optic disk edema, hypercoagulable states (polycythemia, leukemia, or sickle cell disease), glaucoma, retrobulbar compression (such as an orbital tumor), and drugs such as hormonal contraceptives. This form of vascular retinopathy is most prevalent in elderly patients and is characterized by impaired venous outflow.
Diabetic retinopathy results from juvenile or adult diabetes. Microcirculatory changes occur more rapidly when diabetes is poorly controlled. About 90% of patients with juvenile diabetes develop retinopathy within 20 years of onset of diabetes. In adults with diabetes, incidence increases with the duration of diabetes; 80% of patients who have had diabetes for 20 to 25 years develop retinopathy. This condition is a leading cause of acquired adult blindness.
Hypertensive retinopathy results from prolonged hypertensive disease, producing retinal vasospasm, and consequent damage and arteriolar narrowing.
Sickle cell retinopathy results from impaired ability of the sickled cell to pass through microvasculature, producing vaso-occlusion. This leads to microaneurysms, chorioretinal infarction, and retinal detachment.
Signs and symptoms
Central retinal artery occlusion produces sudden, painless, unilateral loss of vision (partial or complete). It may follow amaurosis fugax or transient episodes of unilateral loss of vision lasting from a few seconds to minutes, probably due to vasospasm. This condition typically causes permanent blindness. However, some patients experience spontaneous resolution within hours and regain partial vision.
Central retinal vein occlusion causes reduced visual acuity, allowing perception of only hand movement and light. This condition is painless, except when it results in secondary neovascular glaucoma (uncontrolled proliferation of weak blood vessels). The prognosis is poor — some patients with this condition develop secondary glaucoma within 3 to 4 months after occlusion.
Nonproliferative diabetic retinopathy produces changes in the lining of the retinal blood vessels that cause the vessels to leak plasma or fatty substances, which decrease or block blood flow (nonperfusion) within the retina. This disorder may also produce microaneurysms and small hemorrhages. Nonproliferative retinopathy causes no symptoms in some patients; in others, leakage of fluid into the macular region causes significant loss of central visual acuity (necessary for reading and driving) and diminished night vision.
Proliferative diabetic retinopathy produces fragile new blood vessels on the disk (neovascularization) and elsewhere in the fundus. These vessels can grow into the vitreous and then rupture, causing vitreous hemorrhage with corresponding sudden vision loss. Scar tissue that may form along the new blood vessels can pull on the retina, causing it to tear or even detach.
Symptoms of hypertensive retinopathy include blurred vision, often accompanied by headache. Ophthalmoscopic examination may reveal diffuse binocular narrowing, venular tortuosity, silver wire reflexes, macular stars, and swelling of the head of the optic nerve (disk edema). Severe, prolonged disease eventually produces blindness; mild, prolonged disease, visual defects.
Symptoms of sickle cell retinopathy include peripheral arteriolar occlusions, peripheral arteriovenous anastomoses, sea fan neurovascular fronds, vitreous hemorrhage as tractional forces and vitreous collapse tear fragile neovascular membranes and, with advanced disease, severe vitreous traction and retinal detachment.
Diagnosis
Check visual acuity and then vital signs, including blood pressure. Diagnosis is made on fundal examination with an ophthalmoscope. Determine if female patients are pregnant; hypertensive retinopathy may be an early sign of preeclampsia. (See Diagnostic tests for vascular retinopathies.)
Treatment
No treatment has been shown to control central retinal artery occlusion. However, an attempt is made to release the occlusion into the peripheral circulation. To reduce intraocular pressure, therapy includes acetazolamide I.V., eyeball massage, thrombolysis by intra-arterial injection or I.V., high concentrations of inhaled oxygen, and anterior chamber paracentesis (to try to move the arterial obstruction into the peripheral field).
Therapy for central retinal vein occlusion may include aspirin, which acts as a mild anticoagulant. Patients with central retinal vein occlusion have reported improved vision after direct injection of tissue plasminogen activator into the retinal venous system. Laser photocoagulation can reduce the risk of neovascular glaucoma for some patients whose eyes have widespread capillary nonperfusion.
Treatment for nonproliferative diabetic retinopathy is prophylactic. Careful control of blood glucose levels may reduce the severity of the retinopathy or delay its onset. Patients with early symptoms of microaneurysms should have frequent eye examinations (three to four times per year); children with diabetes should have an annual eye examination.
Treatment for proliferative diabetic retinopathy or severe macular edema is laser photocoagulation, which cauterizes the leaking blood vessels. Laser treatment may be focal (aimed at new blood vessels) or panretinal (placing burns throughout the peripheral retina). Despite treatment, neovascularization continues to proliferate, and vitreous hemorrhage, with or without retinal detachment, may follow. If the blood isn’t absorbed in 6 weeks to 3 months, vitrectomy may restore partial vision.
Treatment for hypertensive retinopathy includes control of blood pressure with appropriate drugs, diet, and exercise. Treating the systemic hypertension should improve the condition of the eyes. If left untreated, hypertensive retinopathy results in severe vision loss.
The treatment goal of sickle cell retinopathy is to reduce the risk of, or prevent or eliminate, retinal neovascularization. Patients with symptoms should be followed twice a year with ocular examinations and dilated retinal evaluation. Proliferative disease should be treated with fluorescein angiography and panretinal photocoagulation. Cryotherapy hasn’t been proven to be effective and has a high complication rate.
Special considerations
❑ Be sure to monitor a patient’s blood pressure if he complains of occipital headache and blurred vision.
Alert Arrange for immediate ophthalmologic evaluation when a patient complains of sudden, unilateral loss of vision. Blindness may be permanent if treatment is delayed.
❑ Encourage a diabetic patient to comply with the prescribed regimen.
❑ For a patient with hypertensive retinopathy, stress the importance of complying with antihypertensive therapy.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
More About Retinal detachment
More Medical Textbooks Online about Retinal detachment
Review other book chapters online related to Retinal detachment:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Retinal detachment (Professional Guide to Diseases (Eighth Edition))
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
