RETINAL VASCULAR DISORDERS
of vision can occur from occlusion of a retinal artery or vein. Such occlusions
may result from atherosclerosis, cardiac val-vular disease, venous stasis,
hypertension, or increased blood viscosity.
supply to and from the ocular fundus is provided by the central retinal artery
and vein. Patients who have suffered a cen-tral retinal vein occlusion report
decreased visual acuity, which may range from mild blurring to vision that is
limited to only hand-motion vision.
ophthalmoscopy of the retina shows optic disc swelling, venous dilation and
tortuousness, retinal hemorrhages, cotton-wool spots, and a “blood and thunder”
(extremely bloody) appear-ance of the retina. The better the initial visual
acuity, the better the general prognosis.
angiography may show extensive areas of capillary closure. The patient should
be monitored carefully over the en-suing several months for signs of
neovascularization and neo-vascular glaucoma. Laser panretinal photocoagulation
may be necessary to treat the abnormal neovascularization. Neovascular-ization
of the iris may cause neovascular glaucoma, which may be difficult to control.
patients with branch retinal vein occlusions are symptom free, whereas others
complain of a sudden loss of vision if the macular area is involved. A more
gradual loss of vision may occur if macular edema associated with the branch
retinal vein occlu-sion develops.
examination, the ocular fundus appears similar to that found with central
retinal vein occlusion; however, only those portions of the retina affected by
the obstructive veins have what is known as a “blood and thunder” appearance.
The diagnostic evaluation and follow-up assessments are the same as for central
retinal vein occlusion. Potential complications are similar. Po-tential associated
conditions include glaucoma, systemic hyper-tension, diabetes mellitus,
hyperlipidemia, and hyperviscosity syndrome.
The patient with central retinal artery occlusion
presents with a sudden loss of vision. Visual acuity is reduced to counting the
ex-aminer’s fingers, or the field of vision is tremendously restricted. A
relative afferent pupillary defect is present. Examination of the ocular fundus
reveals a pale retina with a cherry-red spot at the fovea. The retinal arteries
are thin, and emboli are occasionally seen in the central retinal artery or its
branches. Central retinal artery occlusion is a true ocular emergency. Various
treatments are used, including ocular massage, anterior chamber paracente-sis,
intravenous administration of hyperosmotic agents such as acetazolamide, and
high concentrations of oxygen.