Eye shape is the shape formed by the empty points of an eye. The size and shape of an eye can be crucial to the question of whether a second eye can be formed inside it. A play on a vital point of an eye shape that prevents the formation of a second eye is called a nakade.
Here are some standard eye shapes:
- Eye shape - eye space - discussion
- Capturing Races 1, chapter 2.4 Eye, where, for the context of capturing races, general definitions of eye and unsettled (aka unstable ) overcome dependency on shapes.
 The two different words "unsettled" or "unstable" are used for the meaning "killable with one move". Unsettled is used also in a different context of life and death status. Unstable is used also in a different context of life and death ko types. Using either word has the advantage of consistent usage for one of the other contexts and the disadvantage of possible confusion with usage in that other context.
 An SL page on strong eyes seems to be still missing. Currently unfortunately a user name has occupied that term.