Lens Guide
Single Vision
One power for one viewing distance.
Bifocal
Two powers in one lens.
Progressive
Seamless vision for all distances.
What Is Presbyopia?
The eye's accommodative system becomes less effective with age. It is commonly managed with reading glasses, bifocals, progressive lenses or occupational lenses, depending on your prescription, age, occupation, working distance and lifestyle.
- Holding reading material farther away
- Difficulty reading small print
- Needing brighter light for reading
- Eye fatigue during prolonged near work
- Difficulty switching focus between distance and near
Single Vision Lenses
Single vision lenses have the same prescription power throughout the entire lens. They correct one field of vision, either near, intermediate or distance.
- Distance vision, for clear vision at far distances
- Intermediate vision, for computer and arm's length tasks
- Near vision, for reading and close-up work
Bifocal Lenses
Bifocal lenses have two distinct optical powers in one lens to correct your near and distance vision. A visible line separates the two zones.
Advantages
- Clear vision for distance and near
- Affordable compared to progressive
- Widely available
- Easy adaptation
Limitations
- Visible line between two zones
- No intermediate range
- Image jump when looking through the line
Understanding ADD power
A bifocal prescription carries an ADD (addition) power. For example, distance +1.00 / -0.50 x 90 with an ADD of +2.00.
Distance power + ADD power = near power
Why bifocals are needed
With age, the natural lens inside the eye gradually loses its ability to change shape and focus on near objects. This reduction in accommodation is called presbyopia, and a bifocal compensates for it with an additional near power.
Progressive Lenses
Progressive lenses provide a smooth, gradual change in power from distance at the top to near at the bottom, with no visible dividing line.
Personalised progressive lenses
Not every wearer has the same needs. An office professional needs more intermediate and near area, a frequent driver needs a wide, stable distance field, and an active wearer benefits from a design built for constant changes in viewing distance.
Progressive lenses should not be chosen on prescription alone. Lifestyle matters just as much.
Understanding The Corridor
The corridor is the clear path in a progressive lens that lets you see clearly at all distances. A longer corridor gives a more gradual change in power, a shorter corridor fits a smaller frame.
Peripheral blur and "swim"
Because the power changes across a progressive lens, unwanted optical effects can appear outside the main corridor: peripheral blur, astigmatic distortion, image movement or "swim", and reduced clarity through the sides of the lens.
Modern digital designs control and distribute these aberrations, which widens the usable areas and makes adaptation easier.
Digital / free-form progressive lenses
Instead of relying only on standardised lens geometry, the optical surface is calculated using digital design algorithms.
Optimisation can consider prescription, monocular PD, fitting height, frame geometry, pantoscopic angle, vertex distance, face-form angle, near working distance and individual visual behaviour, so the design is matched to the individual wearer.
Which Lens Is Right For You?
| Feature | Single Vision | Bifocal | Progressive |
|---|---|---|---|
| Distance Vision | |||
| Intermediate Vision | Depends on type | Limited | |
| Near Vision | Depends on type | ||
| Visible Line | No | Yes | No |
| Power Transition | None | Abrupt | Gradual |
| Best For | One main distance | Distance + Near | All-day, all distances |
Scroll the table sideways on mobile to see all columns.
How we choose your lens
Our optical team works through your eye examination, prescription, age-related near requirements, occupation, digital device use, driving requirements, working distance, frame selection and fitting measurements before recommending a lens design.
Need Expert Advice?
Not sure which lens suits you best? Our optical team will take your measurements and recommend the right design.
Book an eye test