circulation. It demonstrates rate of flow, leakage from capillaries, staining of tissues, areas of nonperfusion, and neovascularization. Retinal blood vessels do not normally leak.
Papilledema (choked disk)
(Figs 7.15 and 7.16)
Papilledema is swelling of the optic nerve specifically due to elevated intracranial pressure that causes a reduction in the ability of fluid to exit the eye. It is always serious. The intraocular congestion results in a swollen, elevated optic disc with blurred margins. As it progresses, veins become engorged and flame-shaped hemorrhages and cotton-wool spots develop in the peripapillary area.
In 80% of normal eyes, there are subtle pulsations of the retinal veins as they exit from the globe at the optic cup. If pulsations are not visible, they can almost always be elicited by exerting slight pressure on the globe (through the lid). In papilledema, one cannot see spontaneous or elicited venous pulsations. Swelling of the optic disk damages the surrounding retina and enlarges the blind spot, which helps confirm the diagnosis (Fig. 7.17) and is helpful in monitoring the progression of the disease. The elevated intracranial pressure often causes headache, confusion, nausea, and visual obscurations. Diplopia occurs if the pressure compromises the sixth cranial nerve. Prolonged increased pressure can permanently damage the brain
Fig. 7.17 An enlarged blind spot can be plotted most accurately on a tangent screen. Visual field testing of the size of the blind spot and contraction of the peripheral field must be monitored closely since this is often the only way to know how the disease is being controlled, since spinal tap pressures are dangerous and not that reliable.
Fig. 7.15 Fluorescein angiogram of papilledema with leakage of dye from disk.
Fig. 7.16 Papilledema with elevated disk, engorged veins, and flameshaped hemorrhages.
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and optic nerve. Common causes are side effect of drugs, such as tetracycline, vitamin A toxicity, and retinoids used to treat severe acne and psoriasis. Brain tumors, hemorrhages, and infections also could elevate intracranial pressure.
Idiopathic intracranial hypertension (pseudotumor cerebri) is a condition with elevated pressure that has no obvious cause. It often occurs in young, overweight women and is first discovered during a routine eye exam that reveals papilledema. Treatment of these women includes weight loss, oral Diamox (acetazolamide), and a low-sodium diet. If unsuccessful, then surgical optic nerve sheath fenestration or ventriculoperitoneal shunting could be tried.
Pseudopapilledema
There are many conditions that can mimic the optic disk changes of papilledema and every clue must be considered.
A swollen disk caused by optic neuritis (see Fig. 3.39), is associated with a Marcus Gunn pupil and loss of central vision, whereas in early papilledema, the pupil is normal and there is usually no loss of visual acuity unless edema extends to the macula (Fig. 7.18) or optic atrophy has already occurred.
Early papilledema may be difficult to distinguish from drusen of the disk (Fig. 7.9) and myelinated nerve fibers (Fig. 7.8). All three blur the margin and cause an enlarged blind spot (Fig. 7.17). On fluorescein-angiography, however, only papilledema has leakage of dye
Fig. 7.18 Papilledema with macular star (≠) due to vitamin A toxicity.
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(Fig. 7.15). A hyperopic eye might have a small disk with blurred margin, but there is no leakage with fluorescein angiography. Like papilledema, central retinal vein occlusion (Fig. 7.38) may have venous engorgement, a blurred disk margin, and cotton-wool spots. But in central retinal vein occlusion, the flame hemorrhages extend out to the periphery and there is more loss of vision. Malignant systemic hypertension (BP 220/120 mmHg) also causes a papilledema-like retinal appearance, which is easily distinguished by measuring blood pressure on all patients with blurry disk margins (Fig. 7.22). Orbital diseases decreasing venous outflow from the eye can cause swelling of the disk. Causes include orbital tumors and infections. Idiopathic inflammation of the orbit, also called orbital pseudotumor, (Fig. 5.9), must be considered. Don’t confuse orbital pseudotumor, which does not cause papilledema, with previously discussed pseudotumor cerebri, which does. In these orbital diseases, one looks for localizing signs, such as proptosis. Cavernous sinus disease can also obstruct venous drainage (Fig. 3.60).
Retinal Blood Vessels
Retinal vessel walls are normally transparent. They are visualized because of the blood within them. In arteriosclerosis, as the vessel walls become hyalinized, they develop a white reflex.
The vessel walls may also whiten when inflamed in conditions such as systemic lupus erythematosus (Fig. 1.4), sarcoidosis (Fig. 6.135), cytomegalovirus infection (Fig. 6.147), sickle cell disease and trait (Fig. 7.20). The damaged vessel may eventually develop a permanent white sheath and a thread-like lumen. Loss of blood flow, as occurs in renal artery occlusion, may also cause this change (Fig. 7.30).
Abnormal capillaries may grow inside the eye in a misguided response to ischemia from retinal artery or vein occlusion and proliferative diabetic retinopathy (see book cover).
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They are due to liberation of vascular endothelial growth factor (VEGF). Panretinal laser photocoagulation may be used to destroy large areas of the hypoxic retina thus decreasing the secretion of VEGF. A total of 1,500 burns is administered to each eye in 2 sessions (Fig. 7.19).
The biggest breakthroughs in ophthalmology in recent years are anti-VEGF drugs, ranibuzumob (Lucentis), and bevacizumab (Avastin), which, when injected into the vitreous, causes regression of these abnormal vessels. It is now being used as a first-line, treatment of wet macular degeneration and for macular edema due to retinal vein occlusions and diabetic retinopathy.
Sickle cell hemoglobinopathy leads to red cells taking on a sickle shape in deoxygenated blood (Fig. 7.20). Sickle cell trait (HbAS) affects 8% of African Americans, with 0.4% having sickle cell disease (HbSS) and 0.2% having HbSC disease. Retinal neovascularization resembling “seafans” (Fig. 7.21) occur at the edge of infarcted (pale) areas. Confirm with a sickle cell prep where a deoxygenating agent is added to a patient’s blood. It’s positive if RBCs assume a crescent (sickle) shape.
Fig. 7.19 Panretinal photocoagulation (PRP) uses an argon laser to apply 1500 burns to partially destroy retinal tissue while carefully avoiding the central fovea. Courtesy Daniel Roth, MD.
Fig. 7.20 Sickle cell retinopathy with vascular inflammation (≠), pale areas of ischemIc retina salmon patch intraretinal haemorrhages (≠≠) and pre-retinal haemorrhages (≠≠≠). This occurred in a 26 year-old black male presenting to the emergency department with an acute MI, renal failure, and cholecystitis.
A B
Fig. 7.21A Sickle cell retinopathy with compensatory neovascularization at edge of infarcted retina.
Fig. 7.21B Fluorescein angiogram with leakage from abnormal new vessels.
Reprinted with permission from SLACK, Inc., Cohen, S.B., Greenberg, M., Fletcher, M.E. & Jednock, N.J. (1986). Diagnosis & Management of Ocular Complications of Sickle Cell Hemoglobin Retinopathy, Ophthalmic Surgery, 17(2), 110–116.
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