Blurred vision is a very nonspecific symptom. Blurred vision refers to “fuzzy” or “hazy” vision, like looking through fog. Words can appear smeared or have poorly defined with fuzzy boarders. Sometimes images can have a “ghost image” or a fuzzy second image close to the first. This can be referred to as a “ghost image”. This should be distinguished from visual distortion, where images are bent or wavy, and from blind spots, where images or letters disappear when the eye is moved.
There is a very long list of conditions that can cause blurred vision, many of which do not involve any retinal diseases.
The optical system of the eye. This includes the cornea, which is the clear coat over the eye, the tear film layer on the surface of the eye, and the natural lens in the eye. Any of these structures can cause blurred vision. Two of the most common causes include dry eye syndrome and cataracts.
The vitreous cavity. The vitreous gel naturally shrinks and liquifies as we age. This can cause floaters and, in some people, even “veils” floating in the central cavity of the eye which can result in transient or even constant blurred vision.
The retina. Any retinal condition that affects the macula, which is the center of vision, can cause blurred vision. The list is long, but includes swelling of the retina, scar tissue or “fibrosis” over the retina, retinal detachments, blood vessel occlusions, and macular degeneration.
Neurological causes. These are much less common causes of blurred vision, but if no other cause is found a neurological workup is often recommended. Diseases of the optic nerve and the visual centers of the brain, such as multiple sclerosis, optic neuritis, ischemic optic neuropathy, giant cell arteritis, strokes, tumors and trauma can result in neurological causes of blurred vision.
The first step in evaluating blurred vision is to make an appointment with your optometrist or general ophthalmologist to determine whether this is a treatable cause involving the optical system of the eye. This will most frequently either result in new glasses or a referral for surgery or the appropriate referral to a specialist.