Globally, at least 2.2 billion people have a near or distance vision impairment.[1] In almost half of these cases, the visual impairment may have been preventable or remains untreated.[1]
The majority of people with vision impairment and blindness are over the age of 50 years; however, vision loss can affect people of all ages.[1] In 2020, the leading global causes of blindness in those ages ≥50 years were cataract, followed by glaucoma, undercorrected refractive error, age-related macular degeneration, and diabetic retinopathy.[2]
Vision loss may occur from an abnormality at any point in the visual pathway from the tear film to the occipital cortex. The most important factor to determine initially is the rapidity of symptom onset. Early assessment of the presence or absence of associated symptoms such as pain, double vision, and flashes and/or floaters is also important. This helps to identify patients with potentially life-threatening disease and highlights those requiring prompt ophthalmology evaluation or surgical intervention.[3] [4]
Acute vision loss that occurs suddenly or over the course of several minutes to hours usually requires urgent ophthalmic consultation. People with subacute or chronic vision loss (where vision loss has developed over weeks, months, or years) may still need specialist input, but usually on a non-urgent basis.
Any significant vision loss justifies a call to an ophthalmologist for advice on referral timing.
Vision loss may also be the initial manifestation of a number of systemic diseases for which separate workup is required.[5]
