Retinal Arterial Macroaneurysm
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Retinal Arterial Macroaneurysm

Clinical Description

  • Definition: Acquired retinal arterial macroaneurysms are fusiform or round dilations of retinal arterioles, typically in the posterior fundus within the first three orders of arteriolar bifurcation.
  • Common Location: Often at arteriolar bifurcations or arteriovenous crossings, with the supratemporal artery most frequently involved due to visual impairment risk.
  • Demographics: Predominantly affects women, usually unilateral (10% bilateral), most common in the sixth and seventh decades of life.
  • Prevalence: Estimated at 1 in 9000 (Beijing Eye Study).
  • Associations: Strongly linked to hypertension, arteriosclerotic cardiovascular disease, and serum lipid/lipoprotein abnormalities. Systemic evaluation for these conditions is critical.
  • Symptoms: Asymptomatic if the macula is spared; otherwise, decreased central visual acuity due to retinal edema, exudation, or hemorrhage.
  • Hemorrhage Types: Can occur in subretinal space, intraretinal, beneath the internal limiting membrane, or into the vitreous.
    • Hourglass hemorrhages are characteristic.
  • Complications: Vitreous hemorrhage may lead to angle-closure glaucoma; subretinal hemorrhage may mimic malignant melanoma or age-related macular degeneration.

Diagnosis

  • Fluorescein Angiography (FA):
    • Hypofluorescence due to hemorrhage blocking fluorescence; hyperfluorescence of the macroaneurysm itself.
    • May fail to detect macroaneurysm if obscured by dense hemorrhage.
  • Indocyanine Green Angiography (ICGA):
    • Useful for dense hemorrhages due to near-infrared penetration.
    • Shows pulsatile lesions contiguous with the arterial wall, pathognomonic for macroaneurysms.
  • Optical Coherence Tomography (OCT):
    • Detects foveal edema, subretinal hemorrhage, and structural retinal changes.
    • OCT angiography is noninvasive, effective for locating macroaneurysms, and an alternative to FA/ICGA.
  • Histopathology: Shows arteriolar distension, fibroglial proliferation, dilated capillaries, extravasated blood, lipoidal exudates, and hemosiderin.
  • Pearl Necklace Sign: Hyperreflective dots around cystoid spaces in the outer plexiform layer, seen in exudative macular diseases (not specific to macroaneurysms).
    • Hyperreflective dots arranged as a contiguous ring along the inner wall of cystoid spaces on the macular OCT scan, termed as the pearl necklace sign.

Natural Course

  • Spontaneous Resolution: Many macroaneurysms thrombose and involute spontaneously, with clearing of macular exudate and good visual prognosis.
  • Poor Outcomes: Exudative progression or subretinal hemorrhage can damage the foveal photoreceptor layer, leading to vision loss.
  • Complications: Macular holes or dense submacular hemorrhage are associated with poor visual outcomes.

Treatment

  • Observation: Preferred for asymptomatic cases or those with spontaneous resolution, as long-term visual outcomes may be comparable to treated cases.
  • Intravitreal Bevacizumab:
    • Improves visual acuity and reduces central retinal thickness in symptomatic cases.
    • Faster resolution of hemorrhage and edema compared to observation.
  • Vitrectomy:
    • Used for macular hemorrhage; outcomes vary by hemorrhage location.
    • Poor prognosis with dense submacular or intraretinal hemorrhage.
  • Pneumatic Displacement: With or without tissue plasminogen activator, used for submacular hemorrhage.
  • Laser Photocoagulation:
    • Considered if lipid exudate threatens the fovea, but no clear evidence of benefit.
    • Risk of arteriolar occlusion, especially if the distal arteriole supplies the macula.
  • YAG Laser: Used for premacular hemorrhage.
  • Surgical Excision: Rare, involves excision of macroaneurysm and drainage of submacular hemorrhage; limited evidence.
  • Long-Term Outcomes: Treated and untreated patients often have comparable visual acuity, except in cases with macular holes or severe hemorrhage.

Differential Diagnosis

  • Key Conditions: Diabetic retinopathy, retinal telangiectasia, retinal capillary angioma, cavernous hemangioma, malignant melanoma, and hemorrhagic pigment epithelial detachment (age-related macular degeneration).

 

Treatment Approaches for Retinal Arterial Macroaneurysm (RAMA) from Another Study

  • Observation:
    • Indicated for RAMAs without macular involvement or threat to the macula.
    • In the study, 16 patients were observed; visual acuity (VA) remained stable (initial 0.48 logMAR vs. final 0.35 logMAR, p=0.08).
    • 88% had some hemorrhage, 31% ruptured, but none involved the fovea.
  • Laser Photocoagulation:
    • Used for exudative RAMAs to induce thrombosis and reabsorb exudates.
    • Techniques: Direct (targeting RAMA) or indirect (perilesional) coagulation; often combined.
    • Parameters: Indirect (100-200 µm, 100-200 ms, moderate burns); Direct (200-500 µm, 200-500 ms, soft burns).
    • Study outcomes: 15 patients; VA stable (initial 0.55 logMAR vs. final 0.59 logMAR, p=0.76). 33% lost VA, often due to comorbidities (e.g., CRVO, atrophic creep).
    • Alternative: Subthreshold micropulse laser showed significant VA improvement in some studies (0.8 to 0.36 logMAR over 12 months).
  • Vitrectomy:
    • Indicated for hemorrhagic RAMAs with submacular or premacular bleeding.
    • Techniques: May include recombinant tissue plasminogen activator (rtPA) injection (intravitreal/subretinal), internal limiting membrane (ILM) peeling, pneumatic displacement, or endotamponade (94% in study).
    • Study outcomes: 18 patients; significant VA improvement (initial 1.8 logMAR vs. final 0.77 logMAR, p<0.001). Poor outcomes with macular hole (MH) formation (6% incidence).
    • Timing: Short latency to surgery (mean 3.1 days) associated with better outcomes.
  • Anti-VEGF Therapy:
    • Effective for exudative RAMAs; bevacizumab closed 36/38 RAMAs in one study, with faster visual recovery but no long-term VA advantage (10 months).
    • Minimal destructive side effects, making it suitable for perifoveal RAMAs.
    • Not ideal for subfoveal/subretinal hemorrhage due to need for rapid blood removal.

Complications and Prognosis

  • Complications:
    • Macular Hole (MH): 6% incidence post-RAMA rupture; poor visual prognosis (VA: counting fingers to 20/400). Often discovered during vitrectomy, may be secondary to hemorrhage or ILM peeling.
    • Subretinal hemorrhage: Can lead to retinal degeneration within weeks if untreated, potentially forming disciform fibrotic scars.
    • Retinal detachment: Occurred in 3/18 vitrectomy cases during follow-up.
    • Rare: Massive bleeding post-rtPA (1 case in study).
  • Prognosis:
    • Overall good visual prognosis: Mean VA stable over 3 years with individualized treatment (final VA: 0.58 logMAR, 63% retained reading acuity).
    • Observation and laser groups maintained stable VA; vitrectomy group improved significantly despite worse initial VA.
    • Poor outcomes associated with MH or severe surgical complications.

Management Guidelines

  • Observation: For RAMAs not affecting/threatening the macula, monitored with OCT.
  • Active Treatment: Indicated for actual or impending macular complications.
    • Exudative RAMAs: Laser (direct/indirect) or anti-VEGF.
    • Hemorrhagic RAMAs: Vitrectomy with rtPA, ILM peeling, or tamponade.
  • Cardiovascular Workup: Essential due to association with hypertension and vascular disease.
  • Individualized approach critical due to variable presentation and lack of randomized trials.

Associations

  • Retinal Vein Occlusion (RVO): 27% of photocoagulation group had RVO history (same or fellow eye), suggesting RAMA as a manifestation of generalized vascular susceptibility rather than direct RVO causation.
  • Other: Diabetic retinopathy, radiation retinopathy, central retinal artery occlusion noted in observation group.

Study Specifics

  • Retrospective, single-center study (Kiel University, Germany, 2003-2013) with 49 RAMA cases.
  • Groups: Observation (16), photocoagulation (15), vitrectomy (18).
  • Follow-up: Mean 34 ± 23 months.
  • Limitations: Retrospective design, non-standardized therapy, but provides detailed photocoagulation parameters and large surgical case series.

Citation

Koinzer S, Heckmann J, Tode J, Roider J. Long-term, therapy-related visual outcome of 49 cases with retinal arterial macroaneurysm: a case series and literature review. Br J Ophthalmol. 2015;99(10):1345-1353. doi:10.1136/bjophthalmol-2014-305884.