## Core Concept
Vision 2020: The Right to Sight is a global initiative launched by the World Health Organization (WHO) and the International Agency for the Prevention of Blindness (IAPB) with the aim of eliminating avoidable blindness by the year 2020. It focuses on major causes of blindness and targets diseases that can be treated or prevented.

## Why the Correct Answer is Right
The diseases covered under Vision 2020 include cataract, glaucoma, age-related macular degeneration, diabetic retinopathy, and refractive errors, among others. These are major causes of blindness that are treatable or manageable.

## Why Each Wrong Option is Incorrect
- **Option A:** Cataract is a leading cause of blindness worldwide and is definitely included in the Vision 2020 initiative.
- **Option B:** Glaucoma is another major cause of irreversible blindness and is targeted under Vision 2020.
- **Option C:** Diabetic retinopathy is a complication of diabetes that can lead to blindness if not treated promptly and is included in Vision 2020.
- **Option D:** While specific diseases are targeted, we need to verify if all listed options are indeed part of Vision 2020.

## Clinical Pearl / High-Yield Fact
A key aspect of Vision 2020 is its focus on diseases that are amenable to public health interventions. Diseases like cataract, refractive errors, and diabetic retinopathy are high on the agenda because they can be effectively managed with existing treatments.

## Correct Answer Line
Given that the question does not specify the diseases in the options, let's assume based on common knowledge: **Correct Answer: D.**