A doctor or eye specialist will perform several tests to determine the cause of a sudden loss of vision. If any eyesight remains, the doctor may have the patient read from a vision chart. If the patient is experiencing blindness, the doctor may use a tool called a slit lamp to examine the affected eye under a high level of magnification. He or she may also measure the pressure in the eye. A specialist may opt to perform an angiography, a specialized x-ray that enables the doctor to examine the veins or arteries.

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