Progressive or occupational lenses: which do you need

From the mid-forties onwards, the crystalline lens loses its ability to focus close up. That is presbyopia, and it is neither a disease nor a failure. It is the same process that happens to everybody, with the only difference being that it reaches some people at 42 and others at 48.

What does vary a great deal is the solution. And here the most expensive mistake in all of optics is made: ordering progressive lenses for everything, discovering that at the computer or at the workbench they do not work well, and putting them in a drawer, convinced that “you never got used to them”.

First, the table of distances

Almost everything you do in a day falls into one of these three bands.

The American Academy of Ophthalmology recommends placing the computer screen about 64 centimetres away, roughly the length of your arm. In other words: the screen lives in the intermediate band, not the near one. That detail lies behind most of the complaints we hear about progressive lenses.

What a progressive lens does

A progressive lens changes power continuously from the top, which focuses for distance, to the bottom, which focuses for near. Between the two there is an intermediate corridor.

That corridor is narrow. It has to be: the lens spreads every distance over a few centimetres of height, and at the sides of the corridor there are zones of distortion that the brain learns to ignore. That is why with progressives you move your head instead of your eyes.

It works very well for ordinary life. You go out, you drive, you go into a shop, you look at a price, you read a message, you wave to someone in the distance, all with the same glasses. That is what they are made for, and for that there is no alternative.

What an occupational lens does

An occupational lens, also called a degressive or indoor lens, gives up distance vision and uses all the space gained to widen the intermediate and the near.

The result, in practice: the computer screen is sharp from side to side without hunting for the sweet spot, and without lifting your chin. The whole desk is in focus. You can look at the person opposite you across the table without changing glasses.

The price of that is that beyond two or three metres the vision is no longer correct. You do not drive in occupational lenses and you do not go out in the street in them. They are glasses for being in one place.

They come with different reaches. Some cover up to a metre and a half, which serves a desk. Others reach four or five metres and let you move around a room, see a whole kitchen or teach a class. That choice is made by measuring, not by picking from a catalogue.

The honest comparison

Five profiles and their answer

You work, or spend hours, in front of a screen. Progressives for living, occupational for the desk. It is the clearest case for two pairs. If you can only have one, and your life happens in front of the screen, choose the occupational and keep a separate distance pair for driving.

You read on paper and little else. Ordinary single-vision reading glasses solve it better and more cheaply than anything else. An occupational lens here is over-specified.

You sew, build models, mend watches or paint. The working distance is usually shorter than normal and very fixed. Here the right answer is a single-vision lens calculated for that exact distance, not a progressive. Tell the optometrist how many centimetres away you work, or better, bring the work with you.

You play an instrument from sheet music. The stand is in the intermediate band and you have to keep your head up. With progressives you read the music through the narrow corridor with your neck forced. It is a textbook case for an occupational lens.

You drive a lot, and at night. The progressive is the answer, but the conversation has to include the anti-reflection coating and a check of the distance prescription in low light, which is not the same as with the consulting-room lamp on.

“A lot of people need both” is not a sales line

It is the conclusion that comes out of the table of distances, and it is worth saying plainly, because it sounds like we want to sell you two pairs.

A progressive lens spreads three distances over the height of one lens. An occupational lens spreads two distances over that same height. By pure geometry, the second has more room for each. There is no lens that does both things at once, and anyone telling you otherwise is describing a progressive.

If your budget only stretches to one pair, the progressive is the safe choice, because it is the only one you can leave the house in. If it stretches to two, the second pair should be chosen by where you spend the most consecutive hours, not by where you spend the most hours in total.

Why people sometimes “can’t adapt” to progressives

Before changing the type of lens, there are three things to check. In many cases the problem is one of them.

• The fitting height. If the corridor of the lens is not at the height of your pupil, the corridor is simply not where you are looking. A couple of millimetres are enough to ruin an expensive pair of glasses.
• The frame. A frame that is too shallow cuts off the near zone. A frame that has opened out with use lets the lens drop and shifts every zone upwards.
• The near prescription. A higher addition than necessary narrows the corridor. Less addition, wider corridor.

If you have had progressives made and you do not use them, bring them in before ordering anything new. Very often they can be rescued.

What to ask for at your appointment

Say what you do and at what distance. Literally: “I work with the screen a hand and a half away”, “I read sheet music”, “I make up fishing tackle on the terrace”. That sentence is worth more than half an hour of refraction.

Ask them to measure your working distance in your real posture, sitting the way you actually sit, not upright the way one sits in a consulting room.

And ask about the reach of the occupational lens in metres. If nobody gives you that number, the lens has not been calculated for you.

How we do it here

In Puerto de Mazarrón we see a lot of people who no longer work but who spend hours on the same task: the computer to talk to the grandchildren, reading, sewing, the workshop in the garage. It is exactly the profile occupational lenses were invented for, and hardly anyone offers them, because the easy sale is the progressive.

Bring your current glasses to the appointment, all of them, including the ones you do not use. The conversation starts there.