Difficulty Seeing at Night? A Symptom Guide to Nyctalopia
- Yoon Shwe Yi Han
- 4 hours ago
- 2 min read
Humans can’t see in total darkness, but our eyes are remarkably adapted to low-light conditions. This ability to adjust to dim light helps us navigate a moonlit path, read in a dimly lit room, or drive safely at night. But when this function fails, even simple tasks like moving around a dark house or driving after sunset become difficult and dangerous. This condition is known as Night Blindness, or Nyctalopia.
To understand what causes night blindness, we first need to understand how night vision works.
Understanding night vision
Two key parts of the eye help us see in low light: the retina and the iris.
In the retina, a structure at the back of our eye, there are two different structures assisting our sight : Rods and Cones. These are photoreceptors, our light-detecting cells. Cones are for colour vision and rods enable us to see in the dark.
Another structure of our eye, the iris, also assists us in night vision. Iris acts as a window, adjusting how much light enters our eye. It contains muscles for widening and narrowing the opening of our pupils. If iris does not react properly, it can either widen too much, letting in too much light and leading to light sensitivity, or it can also not allow enough light to enter, making it hard to see in low light conditions.
Why do we get night blindness
Night blindness isn’t a disease itself – it’s a symptom of an underlying problem. These issues generally fall into two categories:
The retina is not working properly
Dysfunction of retina refers to rods reacting too weakly to light, or not reacting at all. There are multiple causes of this and the most common one is vitamin A deficiency. Other causes include diseases such as cone-rod dystrophy, retinitis pigmentosa, macular degeneration, congenital stationary night blindness.
Not enough light reaches the retina
This can happen for conditions resulted not only from dysfuntion of irises but also from unclear pathway for light to pass through, limiting how much light reaches retina. Such conditions can be seen in diseases like cataracts and glaucoma. LASIK and similar procedures can also be a cause.
What should we keep in mind
Since night blindness is a symptom rather than a standalone condition, treatment depends entirely on the underlying cause. Additionally, because the causes of night blindness is very broad, the treatments also vary. If you’re experiencing trouble seeing in low light, it’s important to consult an eye specialist. They can help identify the root cause and recommend the right treatment or adaptations to keep you safe and confident in the dark.
References
Cleveland clinic (2023) https://my.clevelandclinic.org/health/symptoms/10118-night-blindness-nyctalopia
Harvard Health Publishing (2024) https://www.health.harvard.edu/blog/shining-light-on-night-blindness-202401253011
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