What condition of lenses indicates a need for replacement?

Deeply scratched or excessively pitted lenses indicate a need for replacement because these conditions can significantly impair vision and safety. When lenses have deep scratches, they can distort the wearer's view, lead to visual discomfort, and create potential hazards, especially in environments where clear sight is crucial, such as in driving or operating machinery. Excessively pitted lenses can accumulate dirt and moisture in the pits, further degrading visibility and making cleaning ineffective.

Slightly scratched lenses, while they may not provide perfect clarity, often do not interfere with vision to a significant degree and may not warrant immediate replacement. Evenly pitted lenses can also be less severe than their excessively pitted counterparts. Lenses that fit poorly may cause discomfort but do not necessarily affect the quality of vision as a significant optical impairment would. Thus, the most critical factor in determining the need for replacement hinges on the severity of scratches or pitting, with deeply scratched or excessively pitted lenses being the clear indicator for replacement to ensure safety and functionality.