Night vision problems usually present as blurry vision or glare or halo around lights, and they affect a person’s ability to see in low light conditions. These problems occur in people with various diseases, one of which is glaucoma. Learn more about how we see in the dark and how to counteract night vision problems.*

How do the eyes prepare for darkness?

At nighttime, the pupils become larger and let more light in to reach the retina, which is the light-sensitive tissue behind the eye. The retina is covered in two types of photoreceptor cells: 

• Cone cells that give us color in brighter light
• Rod cells that are sensitive in low light and offer black and white vision

Rods are the primary photoreceptors that are activated when it’s dark, giving us black and white vision. Eventually, cones become activated, giving us some color vision at nighttime. When rod cells have completely deteriorated, a person will lose their night vision and experience night blindness.

Testing and risk factors

Because night vision problems can increase one’s risk of falling and ability to drive safely, it’s important to find the underlying cause. Night vision can be impacted by the following diseases and may be considered during your doctor’s testing and diagnosis procedures. 

They may include:

• Cataracts, common in the elderly, may first present as trouble driving at night. They can make vision blurry or dim and cause headlights and streetlights to appear streaky.
• Since glaucoma impacts peripheral vision (which involves more rod cells than cone cells) before damaging central vision, daytime and nighttime vision are both affected. 
• The retina is damaged by macular degeneration, leading to distortion and blind spots in both daytime and nighttime vision.
• Any disease that directly affects the retina, such as retinitis pigmentosa, will harm low-light vision first as rod cells (versus cone cells) are much greater in the retina.
• Night blindness, also known as nyctalopia, is one of the first signs of vitamin A deficiency. When vitamin A deficiency occurs, your eyes produce less rhodopsin, which is the pigment that your rods need to see in low light.
• Several genetic (or congenital) conditions can reduce or block night vision.
• For anyone who needs glasses or contacts to see, for reasons known as refractive errors, night vision will be blurry similar to daytime vision.
• Refractive surgeries, such as Lasik, can cause changes in the shape of the cornea and affect how light bends and may cause glare or halos around lights at night.

Your vision problem could simply signify a need for glasses or contacts to be worn at nighttime, but your doctor will help to determine if it’s something more serious than that. Your ophthalmologist will ask you questions and might use the Pelli-Robson Contrast Sensitivity Chart to determine the level of severity. This test measures how well you can see the contrast between white paper and light grey shapes.

It’s especially important to let your doctor know of night vision problems as soon as possible to avoid risky driving situations and to correct the problem urgently.

*Goel, R.D. (2019, Feb. 4). Night Vision. American Academy of Ophthalmology. https://www.aao.org/eye-health/anatomy/night-vision