Can blindness be a result of mental illness?

Sometimes: Occasionally we see patients who have serious vision loss which is termed "non-organic" or not originating from eye or brain disease. Sometimes this is a manifestation of mental illness and occasionally for personal gain. There are methods to detect this to decipher from true visual blindness.

Yes: Threre is a condition called hysterical blindness which is a type of conversion disorder. This is very rare and typically only happens when people are exposed to unthinkably horrific situations, such as the horrors of war.

Hysterical Condition: Conversion disorders such as hysterical blindness occur when someone witnesses a horrific event which is outside the realm of normal, every-day human experience. It is a very, very rare condition.