## **Core Concept**
The question assesses knowledge of common ophthalmic surgical procedures and their relevance in a district hospital setting. Ophthalmologists perform various surgeries, but the question focuses on the most common one. The correct answer relates to cataract surgery, a fundamental procedure in ophthalmology.

## **Why the Correct Answer is Right**
Cataract surgery, specifically **phacoemulsification**, is the most common operation done by an ophthalmologist. This procedure involves the removal of a cataractous lens and its replacement with an artificial intraocular lens (IOL). Cataracts are a leading cause of blindness worldwide, and this surgery is highly effective and commonly performed.

## **Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because, although procedures like **trabeculectomy** are crucial for glaucoma management, they are not as frequently performed as cataract surgery.
* **Option B:** This option is incorrect as **vitrectomy** is a complex surgery usually reserved for conditions like retinal detachment or severe ocular trauma, not as common as cataract surgery.
* **Option D:** This option is incorrect because **entropion repair** and other eyelid surgeries, while important, are less frequently performed compared to cataract surgery.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **phacoemulsification** has become the gold standard for cataract surgery due to its effectiveness and quick recovery time. It's essential for ophthalmologists, especially in district hospitals, to be proficient in this procedure.

## **Correct Answer:** .