Keratometer is an optical diagnostic instrument which is used for the measurement of front surface curvature of the cornea. It gives the information regarding radii of cornea, directions of the principle meridians of the eye which helps in the determination of extent of astigmatism which plays a key role in lens fitting. Keratometer is manually operated and equipped with highly precise components which increases the accuracy of the measuring device. It can also be used to detect the presence of any corneal distortion. It usually gives the value of corneal curvature in millimetres and in dioptres of power.