In a flashback we see the young Tuvok speaking to a Vulcan master about his unrequited love for a woman. He is so overwhelmed by his feelings his parents insists that he spends time with the Master to learn how to suppress his emotions. While they are having a discussion, the Master tells Tuvok that he has eyes everywhere - in the past - which we can use to understand himself.
For a few seconds I fantasised about having eyes everywhere. Then I went back to watching the episode.
Long story short - Tuvok, Paris, the doctor, and Noss are eventually rescued from the planet. Tuvok makes it clear to Noss that while he respects her they can't develop their relationship. Besides, he is already married. Noss returns home to her own planet.
Fast forward two days, look what I found in today's Metro newspaper:
A creature has been found to have developed 'mirrors' to see in the dark.This goes to show eyes are everywhere.
The spookfish's eyes have evolved into two parts – one which sees upwards and another which reflects light from downwards.
The creature, which prowls the murky depths at 1,000m (3,200ft), uses the trick to spot food and save it from being eaten.
'This is the only vertebrate known to have solved the fundamental optical problem faced by all eyes – how to make an image using a mirror,' said Prof Julian Partridge, of the British and German research team. Four-eyed fish develops 'mirrors' to see
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Science Daily article: Spookfish Uses Mirrors For Eyes