How do I Know if I Need Progressive Glasses

What Are Progressive Lenses?

Progressive lenses have three prescriptions in one pair of glasses. That allows you to do close-up work (like reading a book), middle-distance work (like checking out a website on a computer), or distance viewing (like driving) without needing to change your glasses. They're sometimes called multifocal lenses.

Progressive lenses are an update on bifocal and trifocal lenses. Both of these more traditional types of glasses have telltale lines in the lenses. Progressives have a seamless look. Sometimes they’re called “no-line bifocals”, but that’s not quite right. It would be more accurate to call progressive lenses “no-line trifocals”.

Knowing when to get progressive lenses starts with a visit to your local optometrist. At your comprehensive eye exam, the eye doctor will find out if you need prescription eyewear, and if it turns out you do, they may recommend multifocal lenses.

When should you get progressive lenses instead of other multifocal lenses, including bifocals or trifocals?

Progressive lenses are for you if you want glasses without lines but the same level of visual coverage. There are many types of progressive lenses, and your specific eye condition and lifestyle may influence your choice. The important things to know are that progressive lenses can benefit you if you need more than one prescription or if you have presbyopia. Adults and children are also eligible, which opens up the options for the entire family.

What is segment height for progressive lenses? 

Segment height for progressive lenses refers to the vertical distance from the bottom of your lens to the centre of your pupil. 

How do you measure it?

To measure your segment height, you need your glasses frames, a ruler and a mirror.

Unlike pupillary distance (PD), segment height depends on the glasses frame you're wearing because different frames can have different lens heights. For example, your segment height would be larger if you were wearing oversized glasses and smaller if you were wearing small ones.

Here's how to measure your segment height at home:

1.Stand about eight inches (20 cm) away from a mirror.
2.Wear your glasses.
3.Hold your ruler vertically and align its 0-mm mark with the bottom of your lens.
4.The mm line that aligns with the centre of your pupil is your segment height.
5.Repeat the process three times to ensure a consistent measurement.

Why is segment height important?

Your segment height determines the different focal zones (e.g. distance, computer, reading) for progressive or bifocal lenses.

Segment height is not necessary for single vision prescription lenses because they have only one focal zone, hence the term single vision.