In vision 2020 of NPCB, center of excellence are-

**Core Concept**
The Vision 2020 initiative by the National Programme for Control of Blindness (NPCB) aims to eliminate avoidable blindness in India. The concept of "Centers of Excellence" is crucial in this initiative, focusing on providing high-quality eye care services, training, and research.

**Why the Correct Answer is Right**
Centers of Excellence under Vision 2020 are designated to serve as referral centers for complex eye care services, providing advanced diagnostic and therapeutic facilities. These centers are equipped with state-of-the-art equipment, trained personnel, and a multidisciplinary team approach to manage complex eye conditions. They also play a crucial role in training and capacity-building for other eye care professionals.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it doesn't accurately represent the role of Centers of Excellence in Vision 2020.
**Option B:** This option is incorrect because it is not a recognized designation for eye care facilities under Vision 2020.
**Option C:** This option is incorrect because it is not a specific designation for high-quality eye care services under the NPCB initiative.

**Clinical Pearl / High-Yield Fact**
Centers of Excellence under Vision 2020 are essential for improving the quality and accessibility of eye care services in India, ultimately contributing to the goal of eliminating avoidable blindness.

**Correct Answer: C. District Hospitals**