Brief Answer:
Age related macular degeneration or retinal detachement!

Detailed Answer:
Hi
Thanks for choosing HealthcareMagic,

As it was sudden it can be either-
Age related Macular degeneration or Retinal detachment.

Macular degeneration typically occurs in older people. It is a medical condition which may result in blurred or no vision in the center of the visual field. It is due to damage to the macula of the retina. Diagnosis is made by a complete eye examination.

Second possibility is Retinal detachment. Retinal detachment is a disorder of the eye in which the retina separates from the layer underneath. Symptoms include an increase in the number of floaters, flashes of light, and worsening of visual field.

Diagnosis is by either looking at the back of the eye with an ophthalmoscope or by ultrasound.
Hence I would advice you to please consult your Opthalmologist as early as possible,

Thanks!

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