Visual acuity describes the clarity or sharpness of vision, indicating how well the eye can discern fine details. It measures how clearly one can see objects at a specific distance. This assessment helps determine if the eye’s optical components are focusing light correctly onto the retina, making it a fundamental indicator of overall eye function and health.
Understanding 40/70 Vision
Visual acuity is commonly measured using a Snellen eye chart, with results expressed as a fraction like 20/20. The first number represents the distance a person stands from the chart, and the second indicates the distance at which a person with normal vision could read the same line. 20/20 vision signifies normal visual acuity, meaning one can see at 20 feet what a person with normal vision sees at 20 feet.
40/70 vision means one must be 40 feet away to see what a person with normal vision sees from 70 feet. This indicates a noticeable reduction in visual clarity compared to 20/20 vision. 40/70 vision is considered below average and indicates impaired vision that warrants professional attention.
Common Causes of Impaired Vision
Impaired vision often stems from refractive errors, which occur when the eye’s shape prevents light from focusing precisely on the retina. Myopia (nearsightedness) makes distant objects blurry because light focuses in front of the retina. Hyperopia (farsightedness) results in blurry near vision as light focuses behind the retina.
Astigmatism is another refractive error where an irregularly shaped cornea or lens causes distorted or blurry vision at all distances. Presbyopia, an age-related condition, involves the eye’s lens becoming less flexible, making it difficult to focus on close-up objects. Cataracts, which cloud the eye’s natural lens, or glaucoma, which damages the optic nerve, can also contribute to vision changes.
Correcting Your Vision
Correcting impaired vision often begins with prescription eyeglasses. These lenses bend light to compensate for refractive errors, ensuring light focuses correctly on the retina. Contact lenses offer another alternative, providing vision correction. Both options can improve visual acuity by addressing conditions like myopia, hyperopia, and astigmatism.
Refractive surgery, such as LASIK or PRK, may be an option to reshape the cornea and correct how light enters the eye. Determining the most appropriate solution for 40/70 vision requires a comprehensive eye exam by an eye care professional. A thorough examination helps identify the cause of vision impairment and guides the selection of the best course of treatment.