What symptom indicates the early presence of cataracts or glaucoma when driving?

Halos around headlights is a symptom that often indicates the early presence of cataracts or glaucoma, particularly when driving at night. This phenomenon occurs because cataracts can cause light to scatter as it enters the eye, which creates a halo effect around bright lights, such as vehicle headlights. In glaucoma, increased intraocular pressure can also lead to visual disturbances, including halos. This symptom is especially significant for drivers since it can impact their ability to see clearly and safely navigate roads at night.

In contrast, while double vision, loss of peripheral vision, and difficulty focusing on signs can be associated with various vision problems, they do not specifically indicate the early stages of cataracts or glaucoma in the same way that halos do. Double vision typically suggests issues related to eye muscle coordination or refractive errors, while loss of peripheral vision is more strongly associated with advanced glaucoma rather than early detection. Difficulty focusing on signs can be linked to multiple factors, including age-related changes or refractive errors, but it doesn't directly pinpoint cataracts or glaucoma as clearly as the presence of halos does.