eye care

Do You Know "How Do Progressive Bifocals Work"?

Many people wear progressive bifocals now because their advanced function. When your doctor advises that you need a pair of progressive bifocal, do you ever think about the question:"Why doprogressive bifocals work?"Answer to this question may decide your purchase of this kind of eyeglasses.

Bifocal vision means a person needs two separate prescriptions, one to see clearly at a distance and a different one to see up close. The person is both nearsighted and farsighted.

Hyperopia is an eye condition where a person sees clearly at a distance but has trouble seeing things, especially print, up close. This is also known as farsightedness. The eye doesn’t have enough plus in the eye, but too much minus causing light rays to focus behind or past the retina. A plus prescription is required to pull the light rays back, so to speak, cancelling out the excessive minus in the eye. This causes the light rays to focus on the retina at one focal point so the hyperopic eye can see clearly.

What bifocal lenses do is bring the eyes to near perfect, if not perfect vision. Perfect vision is equated to 20/20 vision, meaning a person can see objects clearly at 20 feet away.

Presbyopia means the eye requires a plus and a minus prescription to see clearly at a distance and up close. Someone with Presbyopia is both myopic and hyperopic. Bifocal eye glass lenses accommodate a Presbyopic person by correcting their distance vision and near vision with one pair of eye glasses.

Myopia is an eye condition where a person sees clearly up close but has trouble seeing objects at a distance. This is also known as nearsightedness. The eye’s cornea has steep curvatures causing it to bulge outward. This is also known as the eye having “too much plus.” As a result, light rays entering through the cornea don’t come to rest at one focal point on the retina. Instead, the light rays come to stop before reaching the retina causing blurred vision. A minus prescription is needed to subtract or cancel out the additional plus and push the light rays’ back to the retina coming to rest at one focal point. This results in the eye seeing clearly.

Trifocal vision means a person needs three separate prescriptions, one to see clearly at a distance, a second one to see intermediately at about an arm’s distance and a third one to see up close.

Note, unlike bifocal vision, single vision means a person needs one prescription in their lenses only. The lenses can have matching prescriptions or different ones. These can consist of a plus or minus prescription, or even no prescription in one eye, while the other has either a plus or a minus prescription, or both.

Bifocal eye glasses work by accommodating eyes that are both nearsighted, or myopic, and farsighted, or hyperopic. This means a person requiring both prescriptions is presbyopic.

If you now have a clear picture of "how do progressive bifocals work", it will be easier to buy a suitable pair of progressive bifocals for you.