Night Blindness: What It Is and How It Affects Driving

Recent changes in daylight saving time, coupled with the gradual decrease in daylight hours as winter approaches, are increasing nighttime driving and, with it, the challenges behind the wheel.

In fact, 60% of Spaniards admit to having visual difficulties when driving at night, according to the Vision Study in Spain 2025 by Clínica Baviera.

Experts warn that this situation, combined with the fact that the time change affects sleep and increases fatigue and drowsiness, can raise the risk of incidents. Therefore, ophthalmologists recommend following a series of guidelines to protect vision in low-light conditions.

Nocturnal vision, or scotopic vision, is the human's natural ability to see in low-light environments, and it has inherent limitations. Under these conditions, color perception is reduced—practically distinguishing only white, grey, and black—visual acuity decreases, central vision becomes less sharp, and moving objects are perceived better than static ones.

Dr. Fernando Llovet, an ophthalmologist and co-founder of Clínica Baviera, explains that "all these limitations mean that, when driving at night, any small uncorrected visual defect is magnified and can increase the risk of an accident." For this reason, the expert emphasizes the importance of regular eye check-ups and using appropriate optical correction before driving in low light.

The Directorate-General for Traffic (DGT) warns that visual capacity can be reduced by up to 20% at night, causing alterations in distance perception and the visual field.

Visual difficulties are accentuated in people with ocular defects or pathologies. Those who have the most trouble driving at night are individuals with retinal diseases, cataracts, myopia, or astigmatism.

However, difficulties can also affect people without a prior visual diagnosis, who experience problems seeing correctly in low-light environments. Dr. Llovet details that, in these situations, the eyes must adapt to an extreme environment for which some individuals' visual systems are not prepared, which can lead to what is known as night blindness or nyctalopia. In case of suspicion, it is recommended to visit an ophthalmologist for examination and treatment.

Additionally, there is the phenomenon known as night myopia, whose exact origin is unknown, but it is believed to be due to an accommodation effort of the lens in low-light conditions when trying to focus on distant objects. "The main symptom of night myopia is that the patient sees well at short distances but has difficulty focusing on distant objects in dark environments," clarifies Llovet.

This phenomenon can affect both people with refractive problems and those with normal vision, who "become myopic at night and are unable to see distant objects clearly." For correction, the use of appropriate glasses or contact lenses for driving in these situations is usually chosen.