Question

Human eye lens is
A. Spherical and can be moved forward.
B. Biconvex and cannot be moved forward.
C. Spherical and cannot be moved forward.
D. Biconvex and can be moved forward.

Answer 1

The human eye lens has convex on both sides. It acts much the same way as an optical glass lens. It can only be moved up and down, right and left.

Complete answer: Humans have two eyes located on the right and left side of the face. They sit on a cavity called the orbit in the skull. Eye movements are controlled by six extraocular muscles. The front part of the eye is made up of sclera, iris and the pupil. The front part of the eye is called the anterior segment. The shape of the eye is not exactly a sphere, rather it is a fused two-piece unit, composed of an anterior segment and the posterior segment. Light enters the eye through the cornea, through the pupil and then through the lens into the retina. The shape of the lens is controlled by the ciliary muscles of the eye. The human eye is biconvex and can not be moved forward, i.e. the lens is a transparent biconvex structure that helps to refract light to be focused onto the retina. The adjustment of the lens is called accommodation. In humans, the refractive power of the lens is approximately 18 dioptres, roughly one-third of the eye's total power.
Hence, the correct answer is option B.

Note: Some of the most common types of eye defects are myopia, hypermetropia, presbyopia, astigmatism, etc. Myopia can be corrected by using concave lenses that would help the image to focus on the retina, hypermetropia can be corrected by using convex lenses, while astigmatism can be corrected by using a special spherical cylindrical lens.