Everything you need to know about Bifocals, Trifocals and Multifocals
Presbyopia and how it affects your vision
Have you noticed yourself holding your phone farther away from your face and squinting to read that text? Having trouble with up-close tasks, like putting on eye make-up? If you just turned 40, you may be experiencing the loss of near focusing ability called presbyopia.
What is presbyopia?
The medical term presbyopia is Greek for “old eyes.” As if you needed one more reminder of how many candles there were on your last birthday cake, right? But before you start obsessing about your ebbing youth, relax. Remember that the loss of clear up-close vision happens to all of us eventually. It’s not a disease, it’s as normal as wrinkles. And there’s an upside! There are eyeglasses — even funky fashionable ones! Or those clever “studious type” specs you’ve been eyeing. Today, whether it’s contact lenses or vision correction surgery, there are so many choices that it may make this rite of passage a little less of a bummer. Don’t worry, whatever you choose, you’ll be reading menus again in no time.
Presbyopia is part of the natural aging process of the eye, and can be easily corrected. Technically, presbyopia is the loss of the eye's ability to change its focus to see objects that are near. Presbyopia generally starts to appear around age 40 and gets progressively worse until around your late 60s, when it usually levels off. It doesn’t usually affect your baseline distance vision.
Presbyopia generally affects men and women equally. Since presbyopia will continue throughout your life, it’s important to understand that it can complicate other common vision conditions like farsightedness, nearsightedness, and astigmatism. Eye experts call these common eye focus conditions refractive errors. But there’s good news ahead.
Bifocal and Multifocal Contact Lenses
Bifocal and multifocal contact lenses are designed to give you good vision when you enter your 40s. Beginning at this age, you may need to hold reading material – like a menu or newspaper – farther from your eyes to see it clearly. This condition is called "presbyopia."
Bifocal and multifocal contact lenses help to alleviate this condition, and are available in both soft and rigid gas permeable (GP) materials.
Bifocals, multifocals – What's the difference?
Bifocal contacts lenses (like bifocal eyeglass lenses) have two powers – one for seeing clearly far away and one for seeing clearly up close. Multifocal contact lenses, like progressive eyeglass lenses, have a range of powers for seeing clearly far away, up close and everywhere in between. ("Multifocal" is also a catch-all term for all lenses with more than one power, including bifocals.)
Types of multifocal contact lenses
Based on design, there are basically two types of multifocal contact lenses:
Simultaneous vision lenses. With these lenses, both distance and near zones of the lens are in front of your pupil at the same time. Although this might sound unworkable, after a short period of time your visual system learns to use the power you need and ignore the other lens power(s), depending on what you are looking at. Simultaneous vision lenses are the most popular type of multifocal contact lens.
They are nearly always soft lenses, and are available in two designs:
Concentric ring designs – These are bifocal lenses with either the distance or near power in the center of the lens, with alternating rings of distance and near powers surrounding it.
Aspheric designs – These are progressive-style multifocal lenses, with many powers blended across the lens surface. Some aspheric lenses have the distance power in the center of the lens; others have the near power in the center.
Alternating vision (or translating) lenses. These are GP multifocal lenses that are designed like bifocal eyeglass lenses. The top part of the lens has the distance power, and the bottom part of the lens contains the near power. When you look straight ahead, your eye is looking through the distance part of the lens. When you look down, your lower lid holds the lens in place while your pupil moves (translates) into the near zone of the lens for reading.
What Are Trifocal Glasses?
In the past, if people who sported bifocals wanted to view an object at an intermediate distance (more than normal reading distance but less than 20 feet away), they had two options:
One option is to approach the object and look through the near segment of the lens. The other is to step farther back from the object and look at it through the distance segment of the lens.
When trifocal glasses entered the optical industry, people could enjoy intermediate vision without the need to move.
Trifocals are multifocal eyewear that offer different lens corrections. Visible lines divide the lens into three segments, including:
Distance vision. This could include driving or looking at a whiteboard.
Intermediate vision. Card playing and staring at the computer screen fall within this range of vision.
Near vision. Close-up reading is a common example.
Eye care specialists recommend this type of multifocal glasses for individuals who suffer from eye conditions like presbyopia (farsightedness caused by aging of the eye) and cataracts.
Types of Trifocal Lenses
The are two main types of trifocal lenses available, including:
- Flat top trifocal lenses. The near and intermediate vision zones are arranged in a D-shape. This shape allows for improved peripheral vision. These lenses are usually easy for people to adjust to.
- Executive trifocal lenses. The intermediate zone of this lens is thinner than flat top trifocals. They may take longer to get used to wearing.
Will multifocal contact lenses work for me?
Most people who try multifocal contact lenses are happy with them. But some compromises may be necessary when you wear these lenses. For example, your distance vision with multifocal contact lenses may not seem clear enough, or you may have trouble with glare at night or not being able to see small print.
In some cases, a better solution for presbyopia may be a monovision or modified monovision fitting of regular ("single vision") contact lenses.
In monovision, you wear a single vision contact lens on one eye for your distance vision and a single vision contact lens on the other eye that has a prescription for your near vision. In modified monovision, you wear a single vision "distance lens" on one eye and a multifocal contact lens on the other eye to help you see better up close.
To determine the best contact lenses for your vision needs when you reach "bifocal age," call our office for a consultation.