Retinal arterial macroaneurysm rupture caused by dissection-like change in the vessel wall.

PURPOSE: To highlight a potential pathogenetic mechanism of retinal arterial macroaneurysm. OBSERVATIONS: A 79-year-old woman presented with a ruptured retinal arterial macroaneurysm in the right eye. One year after treatment, high-resolution multimodal imaging with optical coherence tomography (OCT), OCT angiography, and adaptive optics scanning light ophthalmoscope showed that a narrow passage developed in the vessel wall of the pre-existing retinal arterial macroaneurysm and another macroaneurysm had developed adjacent to the pre-existing one. CONCLUSIONS AND IMPORTANCE: These images suggest the pathogenesis of retinal arterial macroaneurysm (RAM) associated with crack-like changes in the retinal arterial wall, similar to pathologies seen in systemic arteries.

Introduction

Case report

The patient was a 79-year-old woman who was referred to our department with the diagnosis of a ruptured retinal arterial macroaneurysm (RAM) in the right eye. She had no other diseases except for systemic hypertension. The Snellen visual acuity was 20/20 at the initial visit. Images obtained at the initial visit showed a ruptured RAM (Fig. 1).

Fig. 1

Images of retinal arterial macroaneurysm rupture in the right eye of a representative case. Color fundus photographs (left), fluorescein angiogram (upper right), and indocyanine green angiogram (lower right).

After the initial visit, the patient received two intravitreal injections of anti-vascular endothelial growth factor (VEGF) as the treatment for the retinal cystoid spaces involving the fovea.

One year after the initial examination, the adaptive optics scanning light ophthalmoscope (AOSLO) showed another RAM newly developed adjacent to the pre-existing aneurysm (Fig. 2, right). Optical coherence tomography (OCT) showed a narrow passage in the vessel wall shared by the two aneurysms (Fig. 3, left), and OCT angiography (OCTA) showed blood-flow signal corresponding to the passage (Fig. 3, right).

Fig. 2

A new retinal arterial macroaneurysm (RAM) ruptured adjacent to the pre-existing RAM. The adaptive optics scanning light ophthalmoscopy (AOSLO) image shows the ruptured RAM at the initial visit (left). The AOSLO image shows the newly developed aneurysm (arrowheads, right).

Fig. 3

Passage through the two retinal arterial macroaneurysms (RAMs). Optical coherence tomography (OCT) shows a narrow passage (left, black arrow) in the vessel wall shared by the old and new RAMs (arrowheads and white arrows, respectively), and the OCT angiogram shows the blood-flow signal corresponding to the passage (right, black arrow).

Discussion

Retinal arterial macroaneurysm is an acquired, focal dilation of a retinal artery, typically occurring within the first three bifurcations of the central retinal artery. Rupture of a RAM can cause retinal exudative changes and a sudden decrease in visual acuity. Older age, female sex, arteriosclerosis, and collagen diseases are known risk factors for RAM. However, the precise pathology of RAM is not well-understood.

High-resolution non-invasive imaging techniques including OCT, OCTA, and AOSLO have been applied to evaluate the morphologic and functional changes in retinal circulatory diseases such as diabetic retinopathy,3, 4, 5 retinal vein occlusion, and RAM., Using AOSLO, Kadomoto et al. most recently elucidated the processes of loss of pulsation and thrombus formation in RAM. We treated this case with anti-VEGF therapy based on a previous report, which was thought to be less likely to modify the morphology of the RAM vessel wall.

Previous studies with trypsin digestion showed that blowout aneurysm in the retinal artery involves linear splits along the vessel wall. In our case, OCT and OCTA showed a narrow passage with blood flow in the vessel wall of the pre-existing RAM, with another RAM developed adjacent to this. These suggest that a crack in the retinal arterial wall could initiate the pathological condition associated with RAM, which might mimic pathologies in aneurysms or dissections in systemic arteries caused by cracks from the intima to the tunica media of the arterial wall.

Conclusions

High-resolution multimodal imaging with OCT, OCTA, and AOSLO enabled us to visualize the mechanism of RAM formation in vivo. This case suggests that RAM might be caused by crack-like changes in the retinal artery wall, similar to pathologies of systemic arterial disease.

Patient consent

Consent to publish this case report has been obtained from the patient in writing.

Funding

No funding or grant support.

Authorship

All authors attest that they meet the current ICMJE criteria for Authorship.

Declaration of competing interest

The following authors have no financial disclosures: MI, NN.

Y. Muraoka received grant support from Bayer, Novartis Pharma K·K., Senju, and Nidek; S. Ooto received grant support from Novartis Pharma K·K., Bayer, Santen, and Senju; T. Murakami received grant support from Bayer, Novartis Pharma K·K., Santen, and Senju; A. Tsujikawa received grant support from Pfizer, Novartis Pharma K·K., Bayer, Alcon, Santen, Senju, Nidek, and AMO Japan.