Final answer:
In the scenario of a patient developing sudden blindness without physical cause, the suspected defense mechanism is conversion, where psychological stress manifests as a physical symptom.
Step-by-step explanation:
In the case presented where a client experiences sudden onset of blindness without any positive findings in preliminary evaluation and testing, the healthcare team suspects the use of a defense mechanism. Considering the timing of the symptom's onset right before a significant work deadline, the team suggests that this could be an example of conversion. Conversion is a psychological defense mechanism in which emotional distress or unconscious conflict is expressed through physical symptoms that have no organic cause. Unlike repression which blocks out memories, and reaction formation which is the expression of the opposite of what is truly felt, conversion focuses on the transformation of psychological stress into a physical manifestation.