The question of whether people with visual impairment wear glasses often stems from a misunderstanding of the term. Many assume that once a person is classified as visually impaired, standard glasses become completely ineffective. The reality is that the answer depends entirely on the underlying cause and severity of the vision loss. In many cases, glasses play a significant, though often modified, role in maximizing a person’s usable vision.
Defining the Spectrum of Visual Impairment
Visual impairment is a broad medical term describing a decreased ability to see that causes problems not correctable by standard glasses. The spectrum ranges from mild vision loss to total blindness, and it is crucial to distinguish between the correctable and the permanent components of vision loss.
One common cause of reduced vision is a refractive error, which occurs when the eye cannot properly focus light onto the retina. Conditions like nearsightedness, farsightedness, and astigmatism are examples of refractive errors that are easily managed with prescription lenses.
Vision loss can also result from damage to the physical structures of the eye, such as the retina or optic nerve, caused by diseases like glaucoma, diabetic retinopathy, or macular degeneration. When vision loss is permanent and cannot be fully restored by standard glasses, it is classified as low vision. Low vision is typically defined as a visual acuity between 20/70 and 20/400 in the better eye, even after the best possible correction. People are considered legally blind if their best-corrected vision is 20/200 or worse, or if they have a severely restricted field of vision.
Standard Corrective Lenses and Their Effectiveness
Standard prescription lenses function by precisely bending light to ensure it lands directly on the retina, correcting the focal point affected by refractive errors. A concave lens corrects nearsightedness by diverging light rays, while a convex lens converges light to treat farsightedness.
If a person with low vision still retains a component of uncorrected refractive error, standard glasses remain beneficial. The primary goal of standard correction is to establish the clearest possible starting point, maximizing the function of the remaining healthy visual system.
For example, a person with macular degeneration who also has astigmatism requires a correcting lens to sharpen their central focus. Without this correction, their overall vision would be unnecessarily blurred by both the disease and the uncorrected refractive error. Standard lenses do not fix the damage caused by the underlying disease, but they ensure that the patient’s remaining visual capacity is not further diminished by a correctable focusing issue.
If the visual impairment is solely due to damage to the retina or optic nerve, standard lenses offer no therapeutic benefit. The lenses cannot repair dead photoreceptor cells or damaged nerve pathways, meaning the light is focused correctly, but the eye cannot process a clear image.
Glasses Used as Low Vision Tools
Glasses frames are often employed to house specialized optical devices that function as low vision aids, designed to enhance remaining sight rather than correct a refractive error.
These specialized devices include:
- Bioptic telescopic systems, which mount miniature telescopes onto the carrier lenses of glasses. These telescopes allow a user to momentarily magnify distant objects, such as street signs or blackboards, by slightly tilting their head, while the main lens area is used for general walking vision.
- Strong magnifying spectacles, sometimes called prismatic eyeglasses or high addition readers. These are extra-powerful reading glasses that require the reading material to be held much closer to the face. The prismatic component helps the eyes converge at this extremely close working distance.
- Specialized therapeutic filters and tints, frequently housed in standard frames. These tints, such as amber or yellow, reduce debilitating glare and enhance contrast sensitivity, which can be significantly diminished by certain eye diseases.
- Custom designed optics, like E-Scoop glasses, which combine features such as prisms and specific tints to optimize contrast and image size.