Visual acuity, a measure of vision clarity, is a common concern for those with blurry sight. Many wonder about 20/70 vision and its potential for improvement. Understanding the factors contributing to visual acuity and available correction methods can address these concerns. This article explores what 20/70 vision signifies, common correction approaches, and how underlying eye conditions influence the potential for improved sight.
Decoding 20/70 Vision
Visual acuity is measured using a Snellen eye chart. A 20/70 measurement means an individual sees an object clearly from 20 feet away that a person with 20/20 vision can discern from 70 feet. This indicates reduced clarity at a distance. For example, if a person with 20/20 vision reads a street sign from 70 feet, someone with 20/70 vision needs to be 20 feet away to read the same sign.
The World Health Organization classifies this level of vision as moderate visual impairment or moderate low vision. While below average, 20/70 vision is not legally blind, which is typically 20/200 or worse in the better eye with best correction.
Primary Correction Approaches
Correcting 20/70 vision often depends on its root cause, with several primary approaches for refractive errors.
Eyeglasses
Eyeglasses are a common and effective method, using various lens types to bend light onto the retina. Concave lenses correct nearsightedness (myopia), while convex lenses correct farsightedness (hyperopia). Astigmatism, caused by an irregularly shaped cornea or lens, is corrected with cylindrical lenses.
Contact Lenses
Contact lenses offer another option, sitting directly on the eye’s surface. Soft contact lenses are flexible, allowing oxygen to pass through for comfort and adaptation. Rigid gas permeable (RGP) lenses are more durable and provide sharper vision, especially for corneal irregularities, though they may require adjustment. Specialty lenses, such as scleral lenses, vault over the cornea, providing comfort and improved vision for complex prescriptions or corneal conditions.
Refractive Surgery
Refractive surgery reshapes the cornea or implants lenses to alter how light focuses on the retina, potentially reducing or eliminating the need for glasses or contacts. LASIK involves creating a thin corneal flap, reshaping tissue with a laser, and repositioning the flap. PRK reshapes the cornea’s surface after removing its outer layer, which regrows. ICL procedures place a biocompatible lens inside the eye, typically behind the iris, to correct vision without permanently altering the cornea. These options are considered for individuals with stable vision and specific refractive error ranges.
Underlying Causes and Correction Potential
The ability to correct 20/70 vision depends on its underlying cause. Refractive errors, such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism, are common and highly correctable.
Myopia occurs when the eye is too long or the cornea too curved, focusing light in front of the retina. Hyperopia happens when the eye is too short or the cornea too flat, focusing light behind the retina. Astigmatism results from an uneven curvature of the cornea or lens, leading to distorted vision. These conditions can often be fully corrected to 20/20 or near-normal vision with glasses, contact lenses, or refractive surgery.
However, 20/70 vision can also stem from other eye conditions where full correction is limited.
Cataracts
Cataracts, a clouding of the eye’s natural lens, cause blurry vision and are often correctable through surgical removal and replacement with an artificial lens.
Glaucoma
Glaucoma, diseases that damage the optic nerve, can lead to irreversible vision loss, particularly affecting peripheral vision. Treatments can help manage glaucoma and prevent further damage, but lost vision cannot be restored.
Diabetic Retinopathy
Diabetic retinopathy, a complication of diabetes, involves damage to retinal blood vessels, which can leak fluid or grow abnormally, leading to blurred or patchy vision. Treatment can slow its progression, but severe vision loss may be permanent.
Amblyopia
Amblyopia, or “lazy eye,” occurs when the brain and one eye do not work together properly, often due to an imbalance in eye positioning or significant refractive error differences. Early intervention in childhood is important; if left untreated, it may result in permanent reduced vision uncorrectable in adulthood.
Living with Residual Vision
For individuals whose 20/70 vision cannot be fully corrected due to underlying conditions, strategies and specialized aids can help maximize remaining sight.
Low vision specialists, often optometrists or ophthalmologists, develop personalized rehabilitation plans. They assess visual abilities, identify challenges, and recommend tools and techniques to improve daily functioning.
A variety of low vision aids assist with tasks requiring clear vision. Magnifiers, including handheld, stand, and electronic versions, enlarge text and objects for reading and other near tasks. Telescopes, both handheld and spectacle-mounted, help with distance viewing, such as reading street signs or watching television. These devices enhance the ability to perform challenging activities.
Adaptive strategies also optimize remaining vision and maintain independence. Improving lighting, using high-contrast materials, and reducing glare can make objects more discernible. Organizing personal spaces to reduce clutter and implementing tactile markers can aid navigation. Non-optical aids like large print materials, audio cues, and text-to-speech software support reading and information access. Support groups and organizations offer resources and community for individuals living with low vision.