Historical clue formulations

• Like some glasses — 2021-08-04
• Like some lenses — 2019-07-07
• Dual-purpose bit of eyewear — 2018-09-17
• Split right before your eyes? — 2008-02-29
• Like some lenses — 2002-10-15
• Like some glasses — 2002-02-08
• Type of lens — 1995-07-02