What Causes Periodic, Temporary Blindness?
Thorough ocular examination required.
Detailed Answer:
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The condition you have described here regarding your son is medically termed as Amaurosis Fugax.
Though these episodes of visual loss are transient but they are not to be ignored and warrant an immediate and through systemic examination with special emphasis on ocular examination.
The diagnosis may vary for a migraine to something as serious as a stroke.
Loss of vision is attributed to alcholol and tobacco intake and it is known as Toxic Amblyopia. But it rarely transient and doesn't match with the clinical picture in your case. Nevertheless the alchohol intake should be cut down.
The tests that are required:
Complete blood picture
Coagulopathy Studies
Urine Analysis
Electrocardiography
Thorough ocular examination including Fundus examination
Neuroimaging studies.
Please get back to us if you have any further queries.