The lens, a transparent, biconvex structure in the eye, is crucial for focusing light onto the retina, thereby creating clear images. Situated behind the iris and in front of the vitreous body, the lens comprises proteins (primarily crystalline) and water, arranged to maintain transparency. Encased in an elastic capsule, the lens changes shape through the action of ciliary muscles to accommodate near and distant vision. A cataract occurs when the lens becomes cloudy, leading to impaired vision. This condition can develop gradually and impact one or both eyes. Causes of cataracts include aging, genetic predisposition, eye injuries, diseases like diabetes, prolonged steroid use, and UV radiation exposure. Symptoms include blurry vision, difficulty with night vision, glare, and halos around lights, faded colours, and double vision. Cataracts are classified into nuclear, cortical, posterior subcapsular and congenital types. Diagnosis involves comprehensive eye exams, slit-lamp examinations, and retinal exams. Treatment options range from non-surgical interventions, such as eyeglasses and anti-glare sunglasses, to surgical procedures like phacoemulsification, where the cloudy lens is replaced with an artificial intraocular lens (IOL). Preventive measures include regular eye exams, wearing UV-protective eyewear, maintaining a healthy lifestyle, and monitoring medications. Understanding the lens's structure and function and the complexities of cataracts highlights the importance of eye health and the proactive measures necessary for maintaining clear vision.