Night Vision: Why We See Differently in the Dark

If you've noticed that your ability to see in dim light isn't what it used to be, you're not imagining it. Night vision naturally declines with age, and several eye conditions can accelerate this change. Understanding how we see in low light helps explain what's happening.

The retina at the back of the eye contains two types of light-sensitive cells. Cones are concentrated in the central macula and work best in good lighting, providing colour vision and sharp detail. Rods are more numerous toward the edges of the retina and excel in dim conditions, though they don't detect colour or fine detail. When light levels drop, we rely increasingly on our rod cells.

Several factors affect how well we see in the dark. The pupil dilates in low light to let more light reach the retina. As we age, the pupil doesn't open quite as wide as it once did, reducing the amount of light entering the eye. The lens also yellows slightly over time, filtering out some light and reducing contrast.

Cataracts significantly affect night vision, often before they cause noticeable problems in daylight. The clouding lens scatters light, causing halos around lights and increased glare from oncoming headlights when driving. Many people with developing cataracts first notice difficulty with night driving long before daytime vision is affected.

Vitamin A deficiency can impair night vision, though this is uncommon in developed countries with varied diets. The vitamin is essential for the chemical processes that allow rod cells to detect light. Foods rich in vitamin A or beta-carotene, such as orange vegetables, leafy greens, and liver, support this function.

Certain medications can affect night vision as a side effect. If you've noticed changes after starting new medication, mention it to your doctor or pharmacist.

For those struggling with night vision, practical steps can help. Keeping windscreens clean reduces scattered light while driving. Allowing extra time for eyes to adjust when moving between bright and dark environments helps. Ensuring adequate lighting for tasks at home prevents strain.

At Atlantic Home Eyecare, we can assess your vision in various conditions and identify any treatable causes of night vision difficulty. If driving at night has become uncomfortable, it's worth having your eyes examined.