**Question:** Drug used in refractory glaucoma -

A. Trabeculectomy
B. Laser peripheral iridotomy
C. Prostaglandin analogues
D. Carbachol

**Core Concept:** Glaucoma is a group of eye diseases characterized by elevated intraocular pressure (IOP) leading to optic nerve damage and visual field loss. Refractory glaucoma is a severe form of the disease where standard treatments are ineffective.

**Why the Correct Answer is Right:** Trabeculectomy (A) is a surgical procedure that creates a new outflow pathway for the aqueous humor, reducing IOP and slowing optic nerve damage progression. Laser peripheral iridotomy (B) is a non-surgical treatment that creates a new outflow pathway for the aqueous humor by creating a hole in the iris, but it is not specific to refractory glaucoma and is typically used in primary open-angle glaucoma.

Prostaglandin analogues (C) are a class of drugs that reduce intraocular pressure by increasing the outflow of aqueous humor through the trabecular meshwork. Although they are effective in many glaucoma cases, they are not specifically designed for refractory glaucoma and may not be as effective as trabeculectomy.

Carbachol (D) is a muscarinic agonist that increases intraocular pressure by stimulating the ciliary body to produce more aqueous humor. It is not a treatment for refractory glaucoma.

**Why Each Wrong Option is Incorrect:**

- Trabeculectomy is a surgical procedure indicated for refractory glaucoma, while laser peripheral iridotomy is used in primary open-angle glaucoma.
- Prostaglandin analogues are a class of drugs used for glaucoma treatment but are not specifically designed for refractory glaucoma.
- Carbachol is a drug that increases intraocular pressure by stimulating the ciliary body, making it an unsuitable treatment for refractory glaucoma.

**Core Concepts:**

- Glaucoma is a group of eye disorders characterized by elevated intraocular pressure (IOP) leading to optic nerve damage and visual field loss.
- Refractory glaucoma is a severe form of glaucoma where standard treatments are ineffective, and additional treatment options may be required.
- Surgical procedures and drugs are different treatment modalities for glaucoma, each targeting specific aspects of aqueous humor production or outflow.

**Clinical Pearls:**

- Trabeculectomy is a surgical procedure indicated for refractory glaucoma patients who have failed medical therapy.
- Laser peripheral iridotomy is indicated for primary open-angle glaucoma patients who have failed medical therapy.
- Prostaglandin analogues are medications used to lower IOP in various types of glaucoma but are not specifically designed for refractory glaucoma.
- Carbachol increases intraocular pressure by stimulating the ciliary body, making it unsuitable for refractory glaucoma patients.