There are single vision lenses along with bifocals and varifocals tand which type
is more suitable depends on your preference,needs, work and lifestyle.
Single Vision Spectacles
The single vision lens has the same power all the way across and down that corrects
sight for that eye.
It can be used to correct either near vision or distance vision.
For most people under 40, a distance correction is enough to see both near and distance.
Your optician will recommend when to wear your glasses.
Around age 40 and beyond, you may either need separate distance glasses or near glasses
or both. ( this is due to natural ageing of the humans lens to focus fully - see
Single vision reading glasses are ideal for close work and have large area of lens
If now look up into the distance, then vision will be blurred as they are designed
for near work only.
Therefore would need to take off to see into the distance or put on a distance glasses
if needed. Or can peer over the top.
This method is ideal for someone who does not always need to constantly switch between
distance and near. Single vision reading glasses have a large area for comfortable
However it's not always practical to keep taking glasses on and off or peer over
the top in certain occupations or situations - especially if distance glasses are
For example a school teacher may want to read from a book but also needs to glance
across the classroom to see the students.
Or at home, a person may want to read a newspaper or book whilst glancing at the
TV from time to time.
There are lens that are designed to combine both the distance and near prescription
into one lens called a multifocal. These include bifocals and varifocals.
The main difference is bifocal lens has a visible line or shape and has two prescriptions
- one above the line and one immediately in the lower half or shape.
The reading area is larger than varifocal and so some find it easier to read than
The downside is the visible shape is not cosmetically appealing, giving age away.
There is no intermediate prescription for the computer user
The varifocal lenses look like a normal single vision lens as it has no visible reading
shape or line. This is cosmetically nicer.
The varifocal lens has range of powers. It starts with patients own distance prescription
at the top of the lens, and then it gradually increases towards reading prescription
towards the bottom of the lenses.
Therefore varifocal lenses include an intermediate prescription - which is ideal
for computer users.
The varifocal is designed to blend the distance into the near prescription, so that
can leave areas of distortion away from the centre of the lens. It may be harder
to use than a bifocal, and has smaller area of reading compared to a bifocal but
many people are happy with varifocals.
How to use varifocals
Tip - if use central portion of varifocal, by pointing nose and then raising chin
up or down to look at objects, it becomes second nature to use the varifocal.