Name the Eye defect in which cornea becomes uneven.

Name the enzyme present in tears which prevents eye infections.

Name the defect in the following crystal:

What is an ideal crystal ? Name the types of the defects which arise in a crystal.

Name the 3 layers of eye

Name the following: The nerve which connects the eyes to the brain:…………………

A person is unable to see objects distinctly placed within 50 cm from his eyes. (a) Name the defect of vision the person is suffering from and list its two possible causes. (b) Draw ray diagram to show the defect in the above case. (c) Mention the type of lens used by him for the correction of the defect and calculate its power. Assume that the near point for the normal eye is 25 cm. (d) Draw a labelled diagram for the correction of the defect in the above case.

(a) Write the function of each of the following parts of human eye : cornea, iris, crystalline lens, ciliary muscles (b) Millions of people of the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable socity of your city has organised a compaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission how would you contribute in this noble cause ? (i) State the objective of organising such compaigns. (ii) List two arguments which you would give to motivate the people to donate their eyes after death. (iii) List two values which are developed in the persons who actively participate and contribute in such programmes.

A person cannot see distinctly the book placed nearer than 60 cm from his eyes. (i) Name the defect of vision the person is suffering from. (ii) List two possible causes of this defect. (iii) Draw a ray diagram to show this vision defect. (iv) How can this defect be corrected ? (v) Draw a ray diagram to show the correction of this defect.

For the myopia defect in eye, it can be removed by

Name some other defects of eye.