Talk:Retinal Macroaneurysm

From EyeWiki

RETINAL MACROANEURYSM

Jay Chhablani MD

• Retinal macroaneurysms are acquired, usually round, dilations of the large arterioles of the retina.
• Macroaneurysms are associated with systemic hypertension in approximately 75% of patients. (need citation)
• They are associated with exudation and hemorrhage, which may result in decreased visual acuity if it involves the central macula.

DEFINITION AND DESCRIPTION

Retinal arterial macroaneurysms may be defined as fusiform or saccular dilatations of the retinal arteries, usually arising within the first three orders of bifurcation.
Their diameter exceeds 100 micron (arbitrarily the upper limit of typical microaneurysms) but typically is not greater than about 250 m{mu}.(need citation)
• Multiple aneurysms are common, occurring in approximately 20 % of affected eyes. (need citation)
• They usually involve different arteries in the same eye, although 10 % of patients have bilateral disease. (need citation)
• The most common involvement is along the superotemporal or inferotemporal arcades, with the nasal vessels more rarely involved. (need citation)
• They often occur at bifurcation sites and at AV crossings and have been seen to develop in vessels with a documented history of embolic damage. (need citation)
• Approximately 10 % of macroaneurysms are pulsatile on initial presentation.(can be a sign of impending rupture)(need citation)

PATHOPHYSIOLOGY:
• Formation of retinal macroaneurysms is associated with systemic hypertension and atherosclerotic disease, but serum lipid abnormalities have also been reported. (need citation0
• About 10% of patients have focal arterial wall atheroma occurring at defects in the wall, which may be at risk sites of aneurysm formation. (need citation)
• The aneurysms are sites of leakage of exudates and hemorrhage in the macula.
• Over time or after acute hemorrhage, there may be spontaneous thrombosis and closure of the aneurysm; in some cases, the artery may return to normal. (need citation)
The visual prognosis in many patients is excellent, but vision loss that results from retinal macroaneurysm formation usually results from scarring in the macula due either to chronic edema or hemorrhage. (need citation)

CLINICAL PRESENTATION

The typical patient presenting with a macroaneurysm is usually an older woman, greater than 60 yr of age, with an established history of systemic hypertension.(need citation)
• The female preponderance is on the order of 3:1. (need citation)
• Rare before age 60 years.(need citation)
HISTORY:
• Most patients present with sudden onset of painless vision loss in one eye. (need citation)
• If the central macula is spared, the patient may be asymptomatic.
• Aneurysms that present without exudation or hemorrhage are asymptomatic.
• Valsalva may be associated with an increased risk of hemorrhage in some patients.(need citation)

EXAMINATION:
1. Aneurysmal dilation of the retinal arterioles occurs, usually at the site of vessel bifurcation or AV crossing in the major branch retinal arteries. (need citation)
2. The right eye is more commonly affected, & the superotemporal artery is most commonly involved. (need citation)
3. Macroaneurysms have also been reported in cilioretinal arteries and on the optic nerve head. (need citation)
4. Occasionally, there are multiple aneurysms. (need citation)
5. Pulsatile flow is occasionally seen but does not necessarily indicate a higher risk of hemorrhage. (need citation)
6. Leakage of protein-rich serum, leading to circinate exudation and macular edema. Serous retinal detachment can also occur. Bleeding is a common and can occur beneath the retina, the RPE, the ILM or into the vitreous. (need citation)
7. A typical “hourglass hemorrhage” occurs, consisting of simultaneous subretinal and preretinal collections of blood.
8. Lipid exudates can also cause a gradual decrease in vision by migrating into the macula.

IMAGING STUDIES
• Fluorescein angiography (FA)is the most helpful imaging study for the diagnosis.
• Saccular dilation of the arteriolar wall is diagnostic of the disease.
• The FA is particularly important in making the diagnosis when there is hemorrhage (which obscures the vasculature).
• Late fluorescein leakage from within the areas of hemorrhage are characteristic of the aneurysms and may assist in the diagnosis when the vasculature is not visible on direct exam.

NATURAL HISTORY - MAY LEAK, RUPTURE,OR BLEED AND CAUSE VARIOUS COMPLICATIONS
Prognosis is good in cases presenting with bleeding and poorer in those presenting with macular edema.

COMPLICATIONS 
1. CYSTOID MACULAR EDEMA
2. DIFFUSE /FOCAL MACULAR EDEMA
3. SUB INTERNAL LIMITING MEMBRANE (ILM), VITREOUS HEMORRHAGE
4. SECONDARY EPIRETINAL MEMBRANE
5. SEROUS RETINAL DETACHMENT
6. SUBRETINAL PIGMENT EPITHELIAL HEMORRHAGE
7. MACULAR LIPID EXUDATION
8. BRANCH RETINAL VEIN OCCLUSION

DIFFERENTIAL DIAGNOSIS
1. Exudative age-related macular degeneration(AMD)
2. Branch retinal vein occlusion
3. Capillary hemangioma
4. Cavernous hemangioma
5. Diabetic macular edema
6. Choroidal melanoma
7. Subretinal neovascular membranes
8. Background diabetic retinopathy
9. Proliferative diabetic retinopathy
10. Retinal telangiectasis,
11. Leber's miliary aneurysms
12. Von Hippel's angiomatosis
13. Radiation retinopathy
• BRVO have been reported to masquerade as retinal arterial macroaneurysms; this is called the Bonnet sign.
• Bonnet sign consists of intraretinal hemorrhage at an AV crossing simulating a macroaneurysm.
Since approximately 10 % of retinal arterial macroaneurysms present with vitreous hemorrhage, this diagnosis must be borne in mind when no retinal detachment, retinal tear, or avulsed retinal vessel is found after the vitreous hemorrhage clears.

MANAGEMENT
• A quiet macroaneurysm that is asymptomatic without visible leakage should not be treated but should continue to be monitored until spontaneous fibrosis occurs.
• Aneurysms that leak fluid or exudate, or both, and threaten to involve or already involve the central macula may be considered for therapy. Treatment has been shown to shorten the duration of macroaneurysm patency.

LASER PHOTOCOAGULATION (controversial)
• Natural history of the disease suggests that many patients have significant visual recovery without treatment. (need citation)
• Treatment is generally recommended for persistent or progressive exudation in the macula.
• Moderately heavy argon green or yellow dye laser is used with large spot size (500 m) and long duration (0.5 s).
• Direct treatment of the aneurysm is performed.

• LASER HYALOIDOTOMY
• In the setting of dense subhyaloid hemorrhage, YAG laser hyaloidotomy has been performed to release the sequestered blood into the vitreous cavity. Release of blood that is sequestered over the macula may reduce the risk of macular scarring and epiretinal fibrosis. This procedure is controversial due to the risk of macular injury and vitreous hemmorhage.

• SURGICAL EVACUATION
In rare settings where there is vitreous hemorrhage and the etiology of bleeding is unclear, vitrectomy surgery may be indicated. The necessity of removing dense subretinal hemorrhage is very controversial and has the potential of causing iatrogenic complications. The goal is to remove the extravasated blood and to assist in the diagnosis and possible treatment.

References : 1) Albert & Jakobiec's Principles & Practice of Ophthalmology, 3rd Edition (2) The Retina - Stephen Ryan , 3rd Edition