GENERAL KNOWLEDGE

Detailed explanation-1: -The limit of resolution of the human eye is about 0.1 mm, or 100 microns (see Table 1 for metric review). Objects that are smaller than this cannot be seen clearly without magnification. Since most cells are much smaller than 100 microns, we need to use microscopes to see them.

Detailed explanation-2: -Generally speaking, the human eye can see debris and dust that are approximately 25 microns in size. To understand just how small this is, consider that a single hair from your head averages about 70 microns in diameter or 30 times larger than the largest fine particle.

Detailed explanation-3: -Abstract. Ocular optics is normally estimated based on up to 2, 600 measurement points within the pupil of the eye, which implies a lateral resolution of approximately 175 µm for a 9 mm pupil diameter.