Varying a numerical aperture of a laser during lens fragmentation in cataract surgery

A method of treating a lens in a patient's eye with an ultra-short pulsed laser comprising:

• determining, using at least one physical processor, a first region of the lens in the patient's eye to receive a laser beam having a first numerical aperture;
• determining, using the at least one physical processor, a second region of the lens of in the patient's eye to receive a laser beam having a second numerical aperture, the second numerical aperture being lower than the first numerical aperture, and the second region being radially closer, on average, to an iris of the patient's eye than the first region;
• controlling a laser source to deliver the laser beam having the first numerical aperture and a first energy to the first region of the lens;
• and controlling the laser source to deliver the laser beam having the second numerical aperture and a second energy to the second region of the lens without delivering the laser beam having the first numerical aperture and the first energy to the second region of the lens, wherein the first numerical aperture and the first energy are configured to deliver a peak laser energy to a retina of the patient's eye that is less than a safety threshold, and the safety threshold is determined based on a safety standard that conforms to ANSI Z136.1-2000 Standard.