Vision Reduction - Causes and Symptoms

Definition

Reduced vision is one of the most common visual symptoms. It generally refers to a diminished visual acuity, therefore to a lower level of image definition. It can affect one or both eyes, the entire visual field or just one of its regions.

Sight reduction is the consequence of different mechanisms: refraction errors, retinopathies and pathologies that affect the optic nerve or visual pathways. Furthermore, it may be due to the opacification of normally transparent eye structures (cornea, crystalline and vitreous), through which the light rays directed to the retina pass.

The most frequent causes of a decrease in visual acuity at the gradual beginning are pathologies that affect focusing (refraction errors). Also the cataract, the conditions that cause corneal opacification (eg post-traumatic or post-infectious scar) and glaucoma are responsible for a progressive vision reduction. Other possible conditions that manifest themselves with this symptom include: age-related macular degeneration; herpes simplex keratitis; ophthalmic herpes zoster; lesions affecting the cortical optical pathways; retinitis pigmentosa, infectious (eg toxoplasmosis) and associated with systemic diseases (hypertension, systemic lupus erythematosus, diabetes, etc.).

In some cases, however, vision loss can occur suddenly, in a period ranging from a few minutes to a couple of days. The most frequent causes of acute vision loss are trauma, vascular anomalies, ischemic events, retinal detachment and vitreous hemorrhage. In any case, diagnosis and treatment must be as timely as possible.

Other conditions that may result in reduced vision associated with eye pain include acute corneal lesions (abrasions) and optic neuritis. This symptom is less frequent due to the use of some drugs (eg salicylates and quinine).