Visual impairment may make normal daily activities such as driving and reading
difficult or impossible. Fortunately, 80% of all visual impairment can be prevented
or corrected. About two-thirds of visual impairment occurs among people age 50
or older. It is estimated that in 2012, 285 million people worldwide were visually
impaired, and, of these, 39 million had no vision and were blind. People with vision
that is worse than 20/200 with glasses or contact lenses are considered legally blind
in most states in the U.S. An estimated 23.7 million adults and 19 million children
in the U.S. are visually impaired or blind. Of the children, 12 million are visually
impaired due to focus (refractive) errors, a condition that could be easily corrected,
but 1.4 million children are irreversibly blind and need visual rehabilitation interventions
to help them attain full psychological and personal development.

Worldwide, uncorrected refractive errors cause an estimated 43% of moderate and
severe visual impairment. Refractive errors include myopia (nearsightedness), hyperopia
(farsightedness), astigmatism, and presbyopia (difficulty focusing closeup).
For reasons that are not entirely clear, the incidence of myopia is soaring—perhaps
related to screen time and lack of exposure to the UVB radiation in sunlight.
Most refractive errors can be compensated for with glasses or contact lenses. One
widely used procedure to correct vision, LASIK surgery, is not foolproof. Some
people who have had LASIK surgery are left with permanent problems, including
chronic dry eyes, double vision, pain, and light sensitivity. More than 95% of
people who have had LASIK are satisfied with the results. However, if you are concerned
about possible side effects, stick to glasses or contacts.

Cataracts are estimated to cause about one-third and glaucoma about 2% of visual
impairment in the middle- and low-income countries. Cataract formation is associated with ultraviolet light exposure, smoking, diabetes, excessive alcohol use, and age. Wearing dark glasses to filter out ultraviolet light can help prevent cataracts and age-related macular degeneration. Wearing photochromic glasses that darken
when exposed to UV light and glasses with polarized lenses is a good idea. More
than half of Americans over the age of 80 have had cataract surgery. Other disorders
that may cause visual problems include age-related macular degeneration,10 diabetic
retinopathy, corneal clouding, injury, detached retina, several infections including
onchocerciasis and trachoma, and tumors, such as retinoblastoma and optic glioma.
Brain damage from stroke, prematurity, or head trauma can also cause visual

In the United States, other than refractive errors, the leading causes of visual impairment
• Accidents or injuries to the corneal surface of the eye, for example from
chemical burns or sports injuries
• Diabetic retinopathy
• Glaucoma
• Macular degeneration
• Cataracts

This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel.