**Core Concept**
Argon laser trabeculoplasty (ALT) is a non-penetrating surgical procedure used to treat open-angle glaucoma by increasing the outflow of aqueous humor from the eye. This is achieved by applying laser energy to the trabecular meshwork, which enhances trabecular contraction and increases the permeability of the outflow channels.

**Why the Correct Answer is Right**
In open-angle glaucoma, the drainage channels of the eye are open, but the trabecular meshwork becomes less efficient over time, leading to increased intraocular pressure (IOP). ALT helps to restore the function of the trabecular meshwork by creating microscopic burns, which stimulate the contraction of the trabecular beams and increase the outflow of aqueous humor. This reduces IOP and slows the progression of glaucoma.

**Why Each Wrong Option is Incorrect**
**Option A:** Angle closure glaucoma is characterized by a sudden blockage of the drainage channels, and ALT is not effective in this condition.
**Option B:** Angle recession glaucoma is a result of trauma to the eye and may have a different underlying pathology than open-angle glaucoma.
**Option C:** Secondary glaucoma can have various causes, and ALT may not be the most effective treatment for all types of secondary glaucoma.

**Clinical Pearl / High-Yield Fact**
It's essential to differentiate between open-angle and angle-closure glaucoma, as the management strategies and treatment options vary significantly between these two conditions.

**✓ Correct Answer: D. Open angle glaucoma**