It is natural to have poorer vision at night, or in low intensity lighting. But in some people, the difficulties in adapting vision to dim light or darkness are particularly marked. This is the case for people who suffer from night blindness. Night blindness is a symptom of vision disorders such as glaucoma, cataracts, but also of poorly controlled diabetes. Find out what night blindness is, what its symptoms are, its causes, and existing treatments.
Night blindness or night blindness: what is it?
Night blindness or night blindness refers to the difficulty in adapting vision to low light situations and at night. In this way, it is opposed to nyctalopia, which refers to the ability to see clearly in the dark, like cats. To understand this phenomenon, we must return to the functioning of the eye. The back of the eye is lined by the retina, which contains two types of photoreceptors: cones and rods, specifies the University of Arizona. At night, it is the rods that are activated, because they need a weak light source for this, unlike the cones. In cases of night blindness, lesions in the rods are often to blame. You then distinguish shapes poorly, and with a delay (adaptation time greater than normal), when the light intensity decreases sharply. This can be problematic for reacting if you are faced with danger.
Symptoms of night blindness
If we all have better vision in broad daylight than at night, certain signs should alert you and point towards a possible diagnosis of night blindness. These signs, specifies the Barcelona Ophthalmological Center, are difficulty identifying people in front of you, or moving around rooms in low light, difficulty driving at night due to insufficient night vision, problems adapting in the event of a change of light. light intensity (change from strong light to darkness or vice versa). Furthermore, these signs may be accompanied by other symptoms depending on the cause of your night blindness, such as headaches, nausea, great sensitivity to light, poor distance vision, or even blurred vision. Furthermore, depending on the type of night blindness one is experiencing, the back of the eye may reveal whitish lesions.
Causes of night blindness
Several pathologies can lead to night blindness. According to the Barcelona Eye Clinic, the main causes of night blindness are:
- Myopia: you then suffer from blurred distance vision. On the other hand, your near vision is clear.
- Cataract: it occurs mainly in the elderly, due to clouding of the lens with aging. But cataracts can also be present in younger subjects, in cases of poorly controlled diabetes, high blood pressure, smoking, alcoholism, family history of cataracts or even obesity.
- Glaucoma: it reflects damage to the optic nerve due to an increase in intraocular pressure.
- Retinitis pigmentosa: this pathology of genetic origin causes progressive degeneration of the retina.
- Keratoconus: this corneal pathology results in a deformation of the cornea, which then takes on a conical shape.
- A deficiency in vitamin A: rhodopsin, a pigment found in the retina and which is essential for night vision, is synthesized from vitamin A. Any deficiency in vitamin A will therefore have an impact on vision, specifies the MSD Manual. This deficiency can come from diet. It can also result from a pathology such as cystic fibrosis (cystic fibrosis), a genetic disease which leads, among other things, to poor absorption of food, and therefore to vitamin deficiencies (including vitamin A).
- High blood sugar: high blood sugar levels, due to poorly controlled diabetes, can damage the small blood vessels that supply the retina, and therefore impair vision.
Treatments for night blindness
Treatments for night blindness depend on the cause identified. This may involve changing spectacle lenses or contact lenses, if the cause of night blindness is a refraction problem (myopia). In the event of keratoconus or cataract, surgical intervention may be considered. In cases of glaucoma, more effective drug treatment to reduce eye pressure is offered. Finally, in the event of high blood sugar, drug treatment to help regulate blood glucose levels, as well as a balanced diet and regular physical activity are recommended.
Sources
- Night blindness or nyctalopiaUniversity Hospital of Barcelona, 2022
- Vitamin A deficiencyThe MSD Manual, November 2022
- Rods and cones of the human eyeArizona State University, May 31, 2017
- About night blindness or night blindnessBarcelona Ophthalmological Center, April 11, 2019
Read also :
⋙ Vision disorders: causes, symptoms to recognize, list of different disorders, correction
⋙ 7 solutions to improve your eyesight naturally
⋙ Myopia, cataract: 5 preconceived ideas about vision