A Case of Incomplete Central Retinal Artery Occlusion Associated with Short Posterior Ciliary Artery Occlusion

To our knowledge, incomplete central retinal artery occlusion associated with short posterior ciliary artery occlusion is extremely rare. Herein, we describe a case of a 62-year-old man who was referred to our hospital with of transient blindness in his right eye. At initial examination, the patient's best-corrected visual acuity was 18/20 in the right eye. Fundus examination showed multiple soft exudates around the optic disc and mild macular retinal edema in his right eye; however, a cherry red spot on the macula was not detected. Fluorescein angiography revealed delayed dye inflow into the nasal choroidal hemisphere that is supplied by the short posterior ciliary artery. The following day, the patient's visual acuity improved to 20/20. Soft exudates around the optic disc increased during observation and gradually disappeared. His hemodynamic parameters revealed subclavian steal syndrome as examined by cervical ultrasonography and digital subtraction angiography. We speculate that his transient blindness was due to ophthalmic artery spasms. In this particular case, spasms of the ophthalmic artery and occlusion of the short posterior ciliary artery occurred simultaneously. As the short posterior ciliary artery branches from the ophthalmic artery, the anatomical location of the lesion might be near the branching of both arteries.


Introduction
ere are only few reports in the Japanese literature that have presented the incomplete type of central retinal artery occlusion (CRAO), including diminished visual acuity and a residual visual �eld but no complete visual loss, slight retinal edema together with a slight cherry red spot on the macula, and good visual prognosis [1,2]. e ophthalmic artery enters the orbit through the optic canal, usually inferotemporal to the optic nerve. e vessel soon crosses medially over the nerve and gives rise to its �rst branch, the central retinal artery. Aer the central retinal artery branches from the ophthalmic artery, a varying number of posterior ciliary arteries arise. Each of these major posterior ciliary arteries further divides into multiple short posterior ciliary branches that penetrate the sclera medial or lateral to the optic nerve, depending on their respective deviation from the parent medial or lateral posterior ciliary arteries [3][4][5].

Case Report
A 62-year-old man complaining of transient blindness in his right eye on waking was referred to our hospital. e patient had a history of hypertension and hyperlipidemia. At initial examination, he had a best-corrected visual acuity of 18/20 in the right eye, which was noncorrigent, and 20/20 in the le eye. Ocular pressures were normal. Slit lamp examination showed cortical opacities in both lenses. Fundus examination showed multiple so exudates around the optic disc and mild retinal edema in the macula of his right eye; however, a cherry red spot was not detected, and the optic disc appearance was unremarkable ( Figure 1). Fluorescein angiography (FA) revealed a delay of arm-to-retina time and a marked �lling delay of the nasal choroidal hemisphere that is supplied by nasal short posterior ciliary artery (Figure 2(a)). erefore, the choriocapillaris corresponding to the nasal choroidal area �lled slowly and patchily ( Figure 2(b)), and no staining of the arterial wall was detected in the late stage. From these �ndings, the patient was diagnosed with incomplete CRAO associated with short posterior ciliary artery occlusion. Systemic administration of a vasodilator and an antiplatelet agent were started aer the initial examination. On the following day, his right visual acuity improved to 20/20. However, during observation, so exudates increased 2 days aer the initial visit (Figure 3(a)), increased further at 1 week (Figure 3(b)), gradually decreased in 2 weeks (Figure 3(c)), and �nally disappeared at 7 weeks (Figure 3(d)). e patient's blood pressure was 95/80 mmHg in the right arm and 130/80 mmHg in the le arm. Further examinations for evaluating hemodynamics were performed; cervical ultrasonography revealed right subclavian artery stenosis and reversed right vertebral artery �ow. Additionally, digital subtraction angiography demonstrated the stenosis of the following arteries: from the right common carotid artery to the bifurcation of the internal carotid artery, the right brachiocephalic trunk, the right subclavian artery, and the le common carotid artery. On the basis of these �ndings, he was also diagnosed with subclavian steal syndrome. Aer recovery from this event, he did not experience any additional periods of transient blindness.

Discussion
In 2002, Schmidt et al. [12] classi�ed CRAO into 3 stages; stage I of his classi�cation represents �incomplete CRAO� and includes diminished visual acuity and a residual visual �eld but no complete visual loss, slight retinal edema together with a slight cherry red spot on the macula, no increase in retinal signs over several hours, and delayed but not completely interrupted blood �ow revealed by FA. ey also reported that spontaneous recovery usually did not occur during a followup of several hours despite minor retinal �ndings. e fundus changes in stage I described in their literature [12] were very similar to those in our case. Hagimura et al. [13] evaluated 22 patients with CRAO. �yes with poor �nal vision (�nal visual acuity < 0.1, ) showed initially denser retinal opacities with a distinct cherry red spot. �yes with favorable visual outcome (�nal visual acuity > 0.4, ) showed so exudates and faint retinal opacities without a cherry red spot. e �ndings show that the �nal visual outcome mainly depended on the initial visual acuity and funduscopic �ndings. In our patient, so exudates were de�ned during observation and the patient's �nal visual acuity was 20/20.
ere have been few reports in the Japanese literature presenting incomplete CRAO, including diminished visual acuity and a residual visual �eld but no complete visual loss, slight retinal edema together with a slight cherry red spot on the macula, and good visual prognosis [1,2]. e fundus changes seen in these reported cases [1,2] were very similar to those seen in our case. ere have been several reports of CRAO presenting with choroidal circulatory disturbance [6][7][8], and/or anterior ischemic optic neuropathy [7,[9][10][11]. To our knowledge, incomplete CRAO associated with short posterior ciliary artery occlusion is extremely rare [1].
Our patient also had subclavian steal syndrome. Subclavian steal syndrome is a function of the proximal subclavian artery stenoocclusive disease with subsequent retrograde blood �ow in the ipsilateral vertebral artery [14]. Morita et al. [15] described subclavian steal syndrome in a case of arteritis syndrome with bilateral occlusion of common carotid arteries. Souma et al. [16] described a case of reversed ophthalmic artery �ow without occlusion of the internal carotid artery. Although, in their patient, collateral circulation and reversed ophthalmic artery �ow were not blurred, stenosis of common carotid and internal carotid arteries were detected. erefore, it is apparent that our patient had circulation disturbances in the right internal carotid artery and the right ophthalmic artery.
In conclusion, we speculate that the transient blindness experienced by our patient was due to spasms of the ophthalmic artery. In this case, spasms of the ophthalmic artery and occlusion of the short posterior ciliary artery occurred simultaneously. As the short posterior ciliary artery branches from the ophthalmic artery, the anatomical location of the lesion is likely located near the branching of both arteries. ��n��c� �f �n�eres�s e authors have no �nancial or proprietary interests related to this paper.