The lens is a biconvex, transparent crystalline structure which divides the eye into anterior and posterior segments. The lens is made up of lens capsule, lens epithelium, and lens fibres. This chapter covers the congenital and developmental cataract, senile cataract, traumatic cataract, metabolic cataract, toxic cataract, complicated cataract, presenile cataract, clinical features of cataract, management of cataract, management of cataract in children, and anomalies of lens position. The lens is located in a saucer shaped depression called the patellar fossa between the anterior and posterior chamber of the eye. A lens in abnormal position since birth is called Ectopia lentis. Acquired cases are called subluxation and dislocation. In this chapter, 70 multiple choice questions are provided along with their answer.