Bifocal Meaning: Definition, Examples, and Translations
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bifocal
[ˈbaɪˌfoʊkəl ]
Definition
eyewear types
Bifocal lenses are optical lenses that contain two distinct optical powers. They are primarily used to correct presbyopia, a condition that affects the eye's ability to focus on nearby objects as people age. The top section of the lens is designated for distance vision, while the lower part is for near vision. This dual functionality allows wearers to see clearly at different distances without needing to switch between multiple pairs of glasses.
Synonyms
bi-vision, double vision, two-focus.
Examples of usage
- He bought bifocal glasses for reading and driving.
- After struggling to see both closely and far away, she decided to get bifocals.
- The doctor recommended bifocal lenses for his aging vision.
Translations
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Interesting Facts
History
- Benjamin Franklin is often credited with inventing bifocals in the 18th century, aiming to improve vision for reading and distance.
- Before bifocals, people needed to switch between multiple pairs of glasses for different vision needs, complicating daily life.
Optometry
- Bifocals typically have a visible line separating the two lens areas, though modern versions can blend the two seamlessly.
- They are commonly prescribed for people over 40, as vision changes can make it difficult to see clearly at different distances.
Cultural Impact
- Bifocals have been featured in movies and television shows, often highlighting the character's age or experience.
- They are sometimes humorously referred to in jokes about aging, reflecting society's views on vision and maturity.
Science
- The human eye's natural ability to adjust focus for distance diminishes with age, leading to the creation of bifocals.
- Research in optometry continues to evolve, including options like progressive lenses, which are a modern alternative to bifocals.
Origin of 'bifocal'
Main points about word origin
- The term 'bifocal' combines 'bi' meaning two and 'focal' relating to focus, indicating the two different areas for vision.
- The word was first used in print in the early 1820s, reflecting the growing need for varied vision correction as people aged.
The term 'bifocal' is derived from the combination of 'bi-', meaning two, and 'focal', related to focus. The concept of bifocal lenses is attributed to Benjamin Franklin in the 18th century. Franklin is said to have developed the first pair of bifocals by cutting two different lenses in half and combining them into one frame, allowing him to see both far and near without switching glasses. Since then, bifocal lenses have evolved, and modern advancements have led to the creation of progressive lenses that provide a smoother transition between different focal points. The use of bifocals has grown significantly with the aging population, as presbyopia affects nearly everyone after a certain age.