Trifocal lenses

Trifocal lenses are a type of corrective lenses used in optometry and ophthalmology to correct presbyopia, a condition that affects the eye's ability to focus on near objects.

Pronunciation

Tri-fo-cal len-ses

Etymology

The term "trifocal" is derived from the Latin words "tri" meaning three and "focal" meaning focus. This refers to the three different points of focus that these lenses provide: near, intermediate, and distance.

Description

Trifocal lenses are designed with three distinct regions, each with a different refractive power. The top region is for viewing distant objects, the middle region is for intermediate distance, and the bottom region is for near vision. This design allows the wearer to switch focus between different distances without changing glasses.

Usage

Trifocal lenses are commonly prescribed for individuals who have difficulty focusing on near objects, a condition known as presbyopia. They are also used for those who have undergone cataract surgery and need assistance with both near and intermediate vision.

Related Terms

• Bifocal lenses
• Progressive lenses
• Corrective lenses
• Presbyopia
• Cataract surgery

See Also

• Optometry
• Ophthalmology
• Refractive power

External links

• Medical encyclopedia article on Trifocal lenses
• Wikipedia's article - Trifocal lenses

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