Why do I see poorly at night? Main causes of poor night vision

23/09/2025

Do you find it difficult to drive at night or to make out shapes in dimly lit environments? Poor night vision, also known as night blindness or nyctalopia, is a common symptom that affects people of all ages. Although in many cases it does not point to a serious condition, it should be assessed by an ophthalmologist, as it may be the first sign of various eye diseases.

What is nyctalopia or night blindness?

It is defined as difficulty seeing in low-light conditions or in darkness. It may appear as blurred vision, loss of contrast, halos around lights, or an inability to adapt quickly to changes between light and dark.

It is important to understand that there is not always an underlying disease. In normal situations, when it gets dark:

• The pupil dilates to take in more light.
• Colour perception decreases.
• The eye depends more on photoreceptor cells known as rods.

These natural changes can cause a slight loss of sharpness in dark environments, without this implying a medical problem.

Pathological causes of poor night vision

When nyctalopia persists or interferes with daily activities, it is essential to rule out any of the following conditions: 

1. Myopia (short-sightedness)

Myopia prevents clear distance vision, and in poorly lit environments the effect may worsen.

• People with myopia, especially with higher prescriptions, often notice greater difficulty driving at night.
• The blur is intensified because the dilated pupil allows in more unfocused peripheral light.

2. Astigmatism

Astigmatism causes distorted vision both near and far due to an irregularly shaped cornea.

• In darkness, pupil dilation allows more rays to strike irregular areas of the cornea, worsening sharpness.
• In more severe cases, such as keratoconus, astigmatism is more pronounced and may lead to significant nyctalopia.

3. Cataracts

Cataracts cause the loss of transparency of the crystalline lens, our natural lens.

• One of the first symptoms may be blurred night vision.
• Lights may produce glare, halos or bothersome reflections, making night driving difficult.

4. Glaucoma

Glaucoma progressively affects the visual field, beginning at the periphery.

• Although painless, it may present as a reduction of the visual field in darkness, when contrasts are harder to distinguish.
• Detecting it in time is key to preserving vision.

5. Retinitis pigmentosa

This is a hereditary retinal disease that reduces peripheral vision.

• One of its most characteristic signs is early night blindness, even when daytime vision is good.
• The disease is progressive and requires specialised follow-up.

6. Vitamin A deficiency

Vitamin A is essential for visual health, particularly for the function of retinal rods.

• Its deficiency can cause reversible nyctalopia.
• It may result from very restrictive diets, intestinal disease or poor absorption.

When to consult an ophthalmologist

Although many people notice mild changes in night vision as they get older, a marked or sudden loss should be assessed by a specialist. A full eye examination will allow:

• Detection of possible eye conditions.
• Determination of whether the problem is refractive, metabolic or degenerative.
• Establishment of the appropriate treatment or preventive measures.

Nyctalopia may be an isolated symptom or a warning sign. At Barraquer we have the most advanced diagnostic technology to identify the exact cause of poor night vision and to offer the most suitable treatment for each patient.

Dr. José Lamarca Mateu, ophthalmolgist at the Barraquer Ophthalmology Centre