A child was diagnosed with poor vision and loss of vision at night or darkness. What could be disease be and what could be the possible reasons for its onset?

Explanation

**Step-by-Step Solution:**

1. **Identify the Symptoms**: The child is experiencing poor vision and loss of vision specifically at night or in darkness. This indicates a problem related to vision that worsens in low-light conditions.

2. **Recognize the Condition**: Based on the symptoms described, the condition is likely to be "night blindness." Night blindness is characterized by difficulty seeing in low light or darkness.

3. **Determine the Cause**: The primary cause of night blindness, especially in children, is often a deficiency in vitamin A. Vitamin A is essential for the production of rhodopsin, a pigment in the retina that helps the eyes adjust to low-light conditions.

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