Confirmation of choroidal ischaemia causing transient vision
A 66-year-old man presented with a 3-month history of recurrent right transient monocular vision loss (TMVL). He had more than 15 episodes without provocation. He described multiple islands of visual loss that coalesced to complete monocular blindness—persisting for several minutes—followed by recovery in a reverse manner.

While venous access was being obtained for fluorescein angiography (FA), the patient reported onset of an attack. The examination was thus fortuitously done during vision loss.
Normally, following intravenous injection, the dye passes through the short posterior ciliary arteries and appears in the optic disc and choroid within 8–12 s, depending on the age, cardiovascular status of the patient, and speed of dye injection.

The arterial retinal circulation appears 11–18 s after injection. However, in this patient, FA of the right eye showed slightly delayed filling of the central retinal artery and severely delayed filling of the nasal choroid and prelaminar region of the optic disc.

The circulation of the left eye was normal. Examination 1 week later confirmed retinal circulation was normal between attacks. A diagnosis of vasospasm was made and after treatment with nifedipine 5 mg twice a day, the attacks ceased. The patient remained attack free at 8 months' follow-up.

Learning Points:-
- Many attempts have been made to classify TMVL from patients' descriptions to distinguish embolic from non-embolic attacks.

- Further, it has been speculated that the reticulated, patchy pattern of TMVL corresponds to interruption of the choroidal circulation—related to its lobular arrangement. This will very rarely occur due to thromboembolism because of the extensive anastomoses between the posterior ciliary arteries supplying the choroid.

- However, whereas vasospasm of the central retinal artery has been directly observed, choroidal perfusion abnormalities can usually only be identified by FA, and no photographic evidence for this assertion has been published.

- This Clinical Picture provides the first direct confirmation for the proposed theory that the reticulated pattern of TMVL is a signature of transient ischaemia of the choroidal lobular circulation. Clearly, such cases should be managed as vasospasm.

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