Retinal Detachment: This condition often presents with sudden onset of vision changes, including flashes of light, floaters, and a curtain or shadow descending over the visual field. It is a medical emergency requiring prompt treatment.

Optic Neuritis: Characterized by sudden vision loss, often accompanied by pain on eye movement, this condition can be a manifestation of multiple sclerosis or other demyelinating diseases.
Central Retinal Artery Occlusion: Presents with sudden, painless, unilateral loss of vision, which can be a result of an embolic event.
Vitreous Detachment: Although often asymptomatic, a sudden increase in floaters and flashes can indicate a vitreous detachment, which may precede a retinal detachment.

Giant Cell Arteritis: This condition can lead to sudden, painless vision loss in one or both eyes and is associated with headache, jaw claudication, and scalp tenderness. Prompt treatment with corticosteroids is crucial to prevent permanent vision loss.
Stroke or Cerebral Vasculitis: Vision changes can be a presenting symptom of a stroke, especially if the visual pathways in the brain are affected. Cerebral vasculitis can also cause sudden vision changes due to inflammation of the blood vessels supplying the brain.
Diabetic Papillopathy or Diabetic Retinopathy: In patients with diabetes, sudden vision changes can be due to diabetic papillopathy or worsening diabetic retinopathy, including macular edema.

Susac Syndrome: A rare condition characterized by microangiopathic changes in the brain and retina, leading to sudden vision changes, hearing loss, and neurological symptoms.
Leber's Hereditary Optic Neuropathy: A rare inherited condition causing sudden, irreversible vision loss, typically in young males.
Acute Zonal Occult Outer Retinopathy (AZOOR): A rare condition presenting with sudden, unexplained vision loss, often with photopsia and visual field defects, affecting the outer retina.