Eye disease of wife and son (a dictum of medical astrology)

 Can anyone answer the why of this Sutra?

षट्चन्द्रेऽन्त्यरवौ स्त्रियैकनयनःसार्धं तथैकात्मजो।

भूग्राभेन्दुमदा स्फुजित्सुकलहो वन्ध्यस्त्रिपंचाद्यसृक् ।।5।।

If the moon is in 6th and Sun in 12th, then the wife of the native and the son of the native both have an eye defect.