Vision defects: understanding your vision to correct it better

Nearsightedness, farsightedness, astigmatism, presbyopia: learn about the main vision problems, their symptoms, and the appropriate corrective solutions.

When the eye is functioning properly, images of objects, whether near or far, are formed clearly on the retina.
To achieve this, the lens changes shape to adjust the focus according to distance: this is called accommodation. This mechanism allows for clear vision from about ten centimeters to infinity.

When the image does not form correctly on the retina, vision becomes blurred or distorted. This is referred to as a visual defect, also known as ametropia. The main vision defects are:

• nearsightedness,

• farsightedness,

• astigmatism.

From around the age of 45, a natural phenomenon affects everyone: presbyopia, linked to the aging of the lens of the eye, which causes increasing difficulty in seeing close up.

Vision correction involves refocusing the image on the retina using eyeglasses or contact lenses. Today, approximately one in five people worldwide wear glasses.

Myopia is a vision defect caused by an eye that is slightly too long. The image is then formed in front of the retina, resulting in blurred distance vision, while near vision remains clear.

The more severe the myopia, the shorter the distance at which vision is clear.

There are generally three levels of myopia:

• mild myopia: from –0.25 to –2.00 diopters,

• moderate myopia: from –2.25 to –6.00 diopters,

• high myopia: beyond –6.00 diopters.

Diopter is the unit of measurement for visual impairment and the power of the glass or lens that corrects it.

• You squint to see from afar

• You don't recognize faces from a distance

• You lean in excessively close to read or write

Myopia is corrected using negative (concave) lenses or contact lenses, which push the image back onto the retina. The more severe the myopia, the thicker the lenses may be at the edges. Fortunately, today's high-tech lenses are thin, lightweight, and attractive, while still providing excellent visual comfort.

Contact lenses are also a popular alternative, especially for sports or dynamic activities.

Hyperopia is caused by an eye that is slightly too short. The image is formed behind the retina. People with hyperopia generally see better from a distance than up close. In cases of mild hyperopia, vision may appear normal thanks to an effort of accommodation, but at the cost of visual fatigue.

There are also three levels:

• mild hyperopia: from +0.25 to +2.00 diopters,

• moderate hyperopia: from +2.25 to +6.00 diopters,

• severe hyperopia: over +6.00 diopters.

• Frequent headaches
• Tired eyes or feeling of fatigue
• In children, possible onset of strabismus

Hyperopia is corrected with positive (convex) lenses or contact lenses, which bring the image back onto the retina.

Recent advances now make it possible to offer:

• glasses that are thinner in the center,

• aspheric lenses, which are flatter and more aesthetically pleasing,

• better visual comfort, even for high prescriptions.

Astigmatism is usually caused by a slightly oval cornea, rather than a perfectly round one.
Vision is then blurred or distorted, both near and far.

Astigmatism can be associated with other visual defects such as myopia, hyperopia, or presbyopia.

• Difficulty distinguishing certain letters or numbers that are close together

• Distorted or blurred vision

• Eye strain

It is corrected using toric lenses, whose curvature compensates for that of the cornea to restore a clear image.

Presbyopia is a natural change in vision linked to the aging of the lens. The lens gradually loses its flexibility, making it increasingly difficult to focus.

It is a phenomenon comparable to a camera autofocus that has difficulty focusing at close range.

• You move the text away to read it.

• Your arms "are no longer long enough."

• Are you seeking more light?

There are several solutions depending on your situation:

• Reading glasses: only for near vision

• Mid-distance lenses: ideal for office work

• Progressive lenses: the most comprehensive solution, providing clear vision at all distances without visible breaks

If you already wear glasses for another vision problem, progressive lenses are generally the most comfortable and natural solution.

Every visual defect is unique and progressive. Good optical equipment is based on:

• precise correction,

• a suitable choice of glasses,

• personalized support.

At Optique Moitzheim, we take the time to analyze your needs and offer you tailor-made solutions that combine comfort, performance, and aesthetics.

Make an appointment in store and benefit from the expertise of our opticians.