Cataract extraction. Hands of a surgeon performing a cataract extraction on a patient's eye using phacoemulsification. This is minimally invasive surgery to remove the lens of a cataract sufferer. The eye is held open by a metal retractor and the phacoemulsification probe is seen entering the eye. The probe will use ultrasound (very high frequency sound) to break up and remove the defective lens. A cataract is the loss of transparency in the lens of the eye. To restore normal vision, the defective lens must be removed and replaced either by spectacles and contact lenses, or by a replacement lens which is surgically implanted.