It is amazing that the general public has a very eroneous impression of lasers used in ophthalmology.
1. It is commonly believed that cataracts are "dissolved" with laser, before a new intraocular lens is implanted. This is not true. The machine used to fragment the cataract into tiny bits is called a "phaco-emulsification" machine and uses ultrasound energy for the job, not laser.
2. Nd YAG laser is a photo disruptive laser which is used to burn a small hole in the posterior (back) capsule in a condition called 'after cataract', where the capsule left behind after a successful cataract surgery thickens and becomes opaque, obscuring vision,
3. Excimer laser is used to change the shape of the cornea, to get rid of refractive errors, especially in young adults, aged 18 to 40 years , though there is no upper age limit. This is a phot-ablative laser.