Based on the fact that Bertha is 50 years old and cannot differentiate between many items at once, she is most likely suffering from Presbyopia.
This refers to the deficiencies in the eye which are usually caused by man-made events or can also be a result of genetics or aging,
Hence, we can state that because Bertha is 50 years old and gradually has deteriorating eyesight and can not concentrate and differentiate between her many pairs of earrings, she suffers from presbyopia.
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