February 7, 2019

Hyperopia, Myopia, Presbyopia: What's the Difference?

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Read the full NZ Herald article here

Impaired sight is a much more complex issue than most people think – there are a number of different conditions that could cause you to require corrective treatments. The most common issues people have with vision are called refractive (focus) errors, and it’s possible to have more than one of these at the same time! This can make diagnoses confusing, so today, we’re going over three main refractive errors, covering how they change the way you see the world around you, and what you can do about them.

Myopia

To begin with, let’s break down the name itself - Myopia. All the refractive errors we’re going to cover follow similar name conventions, so it makes sense to pull apart where they come from.

First of all, you’ll notice that the suffix ‘-opia’ is attached to all of them. This is Greek, and more or less means ‘of the eye’. The other part of Myopia, ‘Myo-‘, essentially translates to shut or closed, so Myopia means ‘closed eye’. It’s also commonly called near-sightedness.

When Myopia occurs, light focuses in front of the retina, instead of on top of it. The retina is a point at the back of your eye, so when light is being focused in front of it, it is being focused too early for the brain to make sense of it. This makes vision up close no problem, but everything beyond a certain distance will be blurry.

A common treatment for Myopia is the implanting of a phakic lens. Also called an implantable contact lens, or ICL, an ICL lens is typically implanted over top of your eye’s natural lens, leaving the original untouched. There are some causes where a phakic lens can be used to replace an organic lens entirely, and these are known as pseudophakic intra-ocular lenses.

Hyperopia

Since ‘hyper-‘ means more, higher or above depending on context, it makes sense that Hyperopia is the term we use to refer to farsightedness. The error is basically the opposite of Myopia; rather than focusing light too early in the eye, it focuses light too late – the point the lens is focusing light on is further back, behind the retina, and not within the eye at all, making vision at all distances difficult.

Hyperopia is common. Younger eyes are able to adjust for it, but as we get older, the lens in our eye hardens, and this is why many people need reading glasses in their 40s.

This form of focus error has its own name: ‘Presbyopia’, from the Greek ‘presbys’, meaning old man. Everyone develops some level of Presbyopia as they get older, whether they are Myopic, Hyperopic, or neither. This means those with Myopia may find their vision stays fairly accurate in their 50s, as Myopia and Presbyopia can effectively cancel each other out. However, those with Hyperopia will find the process of Presbyopia making their vision even worse.

LASIK can be an effective treatment for all these focus issues, but in certain cases it’s not appropriate. Your doctor or ophthalmologist may instead suggest a refractive lens exchange (RLE).

Astigmatism

The last focus error we’re looking at today is Astigmatism. This describes when the cornea – the window at the front of the eye – is non-circular. Usually, vision is distorted because the cornea is oblong instead of round. It’s worth noting that this can occur alongside any of the other focus issues we have mentioned. Astigmatism can be treated with glasses or contacts, but difficulty arises when a patient has multiple refractive issues, as glasses may not be the best treatment for all of them at the same time.

What can you do?

Luckily, laser eye surgery, and related treatments, such as implantable contact lenses (ICLs) and lens replacement surgery, can permanently treat any of these issues. If you’re looking down the barrel of a lifetime with glasses, and you’d rather explore all the options, talk to re:vision. Our expert team can help you book in a free consultation, valued at over $500! Don’t wait, contact re:vision today.

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