How many eye muscles are present which control all types of eye movement?

Daylight (photopic) vision and colour vision are functions of $P$,while twilight (scotopic) vision is a function of $Q$.
$\quad\quad \quad P\quad\quad\quad Q$

The vitreous chamber is perforated from front to behind by a narrow tube which is known as

How many types of cones are present which are responsible for the colour differentiation?

Which structure is covered by the iris?

The chemical used by doctors to dilate the pupil for examination is