Lesson plan
Hemeralopia
Hemeralopia or day blindness is the inability to see clearly in bright light and is the exact opposite of nyctalopia (night blindness), the inability to see clearly in low light. It is also called heliophobia. It can be described as insufficient adaptation to bright light. In hemeralopia, daytime vision gets worse, characterised by photoaversion (dislike/avoidance of light) rather than photophobia (eye discomfort/pain in light), which is typical of inflammations of the eye. Nighttime vision largely remains unchanged due to the use of rods as opposed to cones (during the day), which are affected by hemeralopia and in turn degrade the daytime optical response. Hence, many patients feel they see better at dusk than in daytime. The word hemeralopia comes from the Greek ημέρα hemera, "day", and αλαός alaos, "blindness". Hemera was the Greek goddess of day, and Nyx was the goddess of night. Hemeralopia has been used to describe night blindness rather than day blindness by many non-English-speaking doctors, causing confusion.
Article summary
Hemeralopia or day blindness is the inability to see clearly in bright light and is the exact opposite of nyctalopia (night blindness), the inability to see clearly in low light. It is also called heliophobia. It can be described as insufficient adaptation to bright light. In hemeralopia, daytime vision gets worse, characterised by photoaversion (dislike/avoidance of light) rather than photophobia (eye discomfort/pain in light), which is typical of inflammations of the eye. Nighttime vision largely remains unchanged due to the use of rods as opposed to cones (during the day), which are affected by hemeralopia and in turn degrade the daytime optical response. Hence, many patients feel they see better at dusk than in daytime. The word hemeralopia comes from the Greek ημέρα hemera, "day", and αλαός alaos, "blindness". Hemera was the Greek goddess of day, and Nyx was the goddess of night. Hemeralopia has been used to describe night blindness rather than day blindness by many non-English-speaking doctors, causing confusion.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
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