Step 1: Scotopic vision.
Scotopic vision describes sight in low light, utilizing rod cells. \[P \Rightarrow 1\]
Step 2: Presbyopia.
Presbyopia is an age-related condition where the eye lens loses flexibility, leading to difficulty focusing on close objects. \[Q \Rightarrow 5\]
Step 3: Emmetropia.
Emmetropia signifies normal vision, characterized by clear distance sight without refractive errors. \[R \Rightarrow 4\]
Step 4: Photopic vision.
Photopic vision refers to sight in bright light, employing cone cells. \[S \Rightarrow 2\] \[\boxed{P-1, \ Q-5, \ R-4, \ S-2}\]