Presbyopia

Presbyopia

For most people, their eyesight treats them pretty well, up until they’re in their 40s. Most of take great vision for granted – we just look at something in the distance, and it’s clear. We just look at something up close, and it’s clear. It’s so easy we don’t even think about it. We’re certainly not aware that there’s an active process involved.

Essentially our eyes act like auto-focus cameras. When they’re working really well, we look into the distance, relax our focussing muscles inside our eyes, and it’s clear almost instantly. When we read, our focussing muscles kick in, we “zoom” in on what we’re reading, and it’s clear almost instantly. The efficiency of this system depends on the softness of the lens on the inside of our eyes. This is incredibly soft at birth, so babies can see ridiculously close things very clearly. Then aging kicks in. By the time a child is 10, some of the lens material has stiffened up a bit, so 10-year-olds can’t focus quite as closely as babies. They can still see things at around 10cm from their eyes, and let’s face it, who cares if they can’t see their noses clearly? Similarly, by the time we hit 20 years of age, we might not see things so well at 10cm from our eyes, and similarly, we don’t care, because we never hold things there anyway.

The closest point to which we can focus essentially keeps moving further away, nice and slowly, until we start to notice it and it bugs us. This is usually in the early 40s for women (classically at 42 or 43), and in the late 40s for men. The process of our lens hardening up is called presbyopia, literally translating from the Latin for “old eyes.” Whoever coined these terms must have done so at a time when 40 was “old”, when we all know it’s not! And hello to all the other 1968 babies out there. So. You may have noticed your arms are getting shorter. What to do?

The big picture is that nothing you can do is without some sort of compromise. But rather than resenting your eyes for letting you down, work with them, and be grateful it’s not 1000 years ago when “40” meant “one foot in the grave!” Embrace your forties! The simplest option is to have some reading glasses made. Put them on for reading, take them off when you’re looking at things further away. You might like to have reasonably shallow frames (either just small frames, alternatively the “lookover” specs) so you have the option of looking over the top of them when you need to while reading. For some people, their days are structured so that they’re constantly changing focus between distance tasks and closer work. Classic examples would be university lecturers, or people going to meetings, switching between data projections and their notepads. For these people, especially if they also need a different lens prescription to help them see clearly in the distance, taking glasses on and off several dozen times a day gets really old, really quickly. For others, when they’re reading or using a computer, that’s all they’re doing, so “dedicated” readers are more appropriate for them.

Progressive lenses (AKA multifocal, varifocal, graduated) are very popular. These are useful for people who’d rather not have to remove their glasses when they change tasks. The top is for distance and the bottom is for up close, and the lens power graduates between the two.
Sounds great, and it’s very popular, but not without compromise. There are always peripheral distortions in graduated lenses, and these can throw you for six in the first week or two of wearing them. They can make the world “wobble” for a while, and for around 10% of the population, this “wobble” never goes away. For this reason, most lens manufacturers offer guarantees on progressive lenses – if you’re one of the 10% of the population who can’t get used to them, you can have them exchanged for something else. This might be a bifocal lens; bifocals have distance and reading areas separated by a “line” in the lens. They’re easier to get used to and generally have a bit more width available in the lens for reading. The compromise is that there’s usually a “no-man’s land” – typically from just beyond arm’s length to around “window-shopping” distance – where vision is not so clear. Trifocals are another option – they take the no-man’s land into account, and they have 2 lines on the lens.

Contact lenses often work well for people who need a reading correction. If you have 2 eyes that work pretty much equally well, monovision contact lenses can work well for you. There are also bifocal contact lenses available, although at ICU we steer away from these as the degree of compromise they offer doesn’t gel with our philosophy of giving you the best vision you can have.

Finally, another option is monovision laser surgery – this is the same idea as monovision contact lenses, but more permanent. One eye is turned into a reading eye, the other eye is left alone (or turned into a distance eye if you also need distance glasses) and your brain chooses between the two depending on what you’re doing.