**Core Concept**
VISION 2020 is a global initiative launched by the World Health Organization (WHO) and the International Agency for the Prevention of Blindness (IAPB) to eliminate avoidable blindness by the year 2020. The program focuses on preventing and treating major causes of blindness, particularly in developing countries. Vision 2020 aims to reduce the global prevalence of avoidable blindness by 50% by 2020.

**Why the Correct Answer is Right**
The target diseases under VISION 2020 include cataract, childhood blindness, chronic eye diseases, and refractive errors. Cataract is the leading cause of blindness worldwide, accounting for approximately 51% of all cases. Childhood blindness is another major concern, with causes including cataract, glaucoma, and refractive errors. Chronic eye diseases, such as age-related macular degeneration and diabetic retinopathy, are also targeted under VISION 2020. Refractive errors, including myopia, hyperopia, and astigmatism, are common causes of vision impairment and are addressed under the program.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because cataract is not the only target disease under VISION 2020; childhood blindness, chronic eye diseases, and refractive errors are also included.
* **Option B:** This option is incorrect because age-related macular degeneration is a chronic eye disease, but it is not the only one targeted under VISION 2020.
* **Option C:** This option is incorrect because glaucoma is a cause of childhood blindness, but it is not the only one; childhood blindness has multiple causes, including cataract, glaucoma, and refractive errors.

**Clinical Pearl / High-Yield Fact**
VISION 2020 emphasizes the importance of integrating eye care into primary healthcare services, particularly in developing countries. This approach aims to increase access to eye care services and reduce the burden of avoidable blindness.

**Correct Answer:** C. Chronic eye diseases, cataract, childhood blindness, and refractive errors.