**Core Concept**
The management of after cataract, also known as posterior capsule opacification, involves the use of a specific type of laser to create a hole in the posterior lens capsule, allowing for improved vision. This procedure is a common complication following cataract surgery.

**Why the Correct Answer is Right**
The Nd-YAG (Neodymium-Doped Yttrium Aluminum Garnet) laser is used for this purpose due to its ability to produce high-energy pulses that can precisely create a hole in the posterior lens capsule without damaging the surrounding tissue. This laser emits a wavelength of 1064 nanometers, which is selectively absorbed by water molecules in the lens capsule, causing a precise and controlled disruption of the capsule. The Nd-YAG laser is specifically designed for posterior capsulotomy and is a standard treatment for after cataract.

**Why Each Wrong Option is Incorrect**
**Option A:** Argon lasers are typically used in ophthalmology for procedures such as panretinal photocoagulation for diabetic retinopathy and laser trabeculoplasty for glaucoma, but they are not suitable for creating a hole in the posterior lens capsule.

**Option B:** Krypton lasers are also used in ophthalmology, but primarily for retinal photocoagulation and panretinal photocoagulation. They are not used for posterior capsulotomy.

**Option D:** Excimer lasers are used in refractive surgery, such as LASIK and PRK, to reshape the cornea and correct vision. They are not used for posterior capsulotomy.

**Clinical Pearl / High-Yield Fact**
It's essential to note that Nd-YAG laser posterior capsulotomy should only be performed by experienced ophthalmologists, as the procedure requires precise control to avoid complications such as retinal detachment or intraocular inflammation.

**✓ Correct Answer: C. Nd-YAG**