Clinical description

Acquired retinal macroaneurysms are fusiform or round dilations of the retinal arterioles that occur in the posterior fundus within the first three orders of arteriolar bifurcation. Often they are located at the site of an arteriolar bifurcation or an arteriovenous crossing (Fig. 52.1). The supratemporal artery is the most commonly reported site of involvement because patients with such involvement are more likely to have visual impairment. Women make up the majority of reported cases. Most cases are unilateral, while 10% may be bilateral. Retinal macroaneurysm was estimated to occur in 1 in 9000 in the Beijing Eye Study.¹

Fig. 52.1 (A) A 62-year-old woman with hypertension had a subretinal hemorrhage associated with a macroaneurysm in her left supratemporal artery. (B) The fluorescein angiogram demonstrated hypofluorescence from blockage from the retinal hemorrhage and hyperfluorescence of the retinal macroaneurysm itself, apparent as a round dilation located at the arteriolar bifurcation.

Most commonly, retinal macroaneurysm affects patients in the sixth and seventh decades of life. Often associated are vascular problems such as hypertension and general arteriosclerotic cardiovascular disease, as noted by Robertson,² who first coined the term retinal macroaneurysm. Uncontrolled hypertension can present with a retinal artery macroaneurysm and its accompanying vitreous hemorrhage.³ Other investigators have confirmed this association with hypertension.⁴ Serum lipid and lipoprotein abnormalities have also been reported in patients with this condition.⁵ Systemic investigations for hypertension and cardiovascular disease should be conducted in patients who have a retinal arteriolar macroaneurysm.

Although a patient with a retinal arteriolar macroaneurysm may be asymptomatic if the macula is not involved (Fig. 52.2), the most common clinical symptom is decline in central visual acuity as a result of retinal edema, exudation, or hemorrhage.⁶ Bleeding from macroaneurysms can occur in the subretinal space, into the retina, beneath the internal limiting membrane, or into the vitreous. So-called hourglass hemorrhages are typical. Hemorrhage in the space beneath the retinal pigment epithelium may produce a dark lesion simulating an ocular tumor such as malignant melanoma,⁷ or a lesion associated with age-related macular degeneration. A complication of the vitreous hemorrhage also includes the development of angle closure glaucoma.⁸

Fig. 52.2 (A) The retinal hemorrhage superior to the optic disc, associated with a retinal macroaneurysm, caused no ocular symptoms. (B) Six months later, the retinal macroaneurysm is partially obstructed by the resolving retinal hemorrhage, with a surrounding ring of lipid. (C) Eight months later, the macroaneurysm has spontaneously involuted, with complete resolution of the hemorrhage and a decrease in the lipid.

The hemorrhage may also partially or completely obscure the aneurysm (Fig. 52.3). Occasionally, multiple macroaneurysms occur. Other retinal microvascular changes associated with macroaneurysms include widening of the periarterial capillary-free zone around the area of the aneurysm, capillary dilation and nonperfusion, microaneurysms, and artery-to-artery collaterals.

Fig. 52.3 (A) A preretinal hemorrhage partially obscures the retinal macroaneurysm. (B) The fluorescein angiogram shows the hyperfluorescence that corresponds to the hemorrhage and the hyperfluorescence of the retinal macroaneurysm. (C) At 20 months later, there is spontaneous resolution of the hemorrhage and the retinal macroaneurysm.

Diagnosis of retinal macroaneurysm