It's no wonder that so many people get confused by the terms nearsightedness
and farsightedness, these terms often so oversimplified that they just don't make
sense in real-world use cases in this video I'll explain what it truly means
to be nearsighted and what it means to be farsighted. Hi I'm Martin Oguzie and
this is Martin's eye tips. Thank you for joining, me on this channel we're all
about bringing your eye care tips, how to videos and product reviews all designed
to help you see better, see more, comfortably and be less anxious about
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that way you get reminded every time I release a new video, so let's get started
with today's video all about nearsightedness and farsightedness.
Nearsightedness and farsightedness are two terms we use to explain the error
that can occur in the shape of the cornea that leads to light focusing in
front of the retina if you are nearsighted or behind the retina if
you're farsighted. Now let's make sense of these terms before we go any further
nearsightedness is often also referred to as being short-sighted or being
myopic and It basically refers to the fact that light focuses in front of the
retina and you can think of it as having sight for short distances. Farsighted on
the other hand is also referred to as being long sighted or being hyperoptic (hyperopia)
and this is when light focus is long or behind the retina and you can think of
this as having sight for longer distances which then also means that in
theory you have problems seeing close up but you're fine seeing further away. Now
these terms then cause confusion because they don't always make sense,
particularly if you're somebody with far sightedness. In the case of
nearsightedness it generally does apply and does make sense so think of
nearsightedness as I said before; as having sight for short distances
so people who are nearsighted usually find that their vision for further away
things will be blurred to some degree depending on how short-sighted or how
nearsighted they are, whereas they will always have good clarity of vision close
up and this applies even later on in life depending on
how much nearsightedness that they have. Now if you farsighted and under the age
of 40 then you probably find that if you've got a prescription that's about
+2 or less that you can generally focus well in all distances, so the term
farsightedness may not make any sense to you whatsoever because it just doesn't
impact you in that way. Now if on the other hand you are over 40 and you are
farsighted you may want to find that the opposite is true you may not be able to
see very well for close up things or things very far away. Now the reason for
this is because when we all get to about age 40 we start to have problems with
our focusing close up and this affects our ability to be able to compensate for
our long-sightedness or farsightedness and as a result if we start to find that
it affects us far away but also we start to have problems with close up as
well so it tends to be a little bit of a double whammy at this stage in life. I've
made a previous video about presbyopia if you want to check that out please
check out the link in the top right corner. And the other confusing aspect of
it when you're far-sighted is that regardless of age if you have a high
prescription you generally may find that you struggle close up as well as far
sight as well, so while the term is supposed to mean that you have sight for
far distances and this can be true but it has the exception of your age and
also how much farsightedness you have. so what is it that's going on in the eye in
both cases that explains what we just described? In both cases of
nearsightedness and farsightedness they're neither diseases but it's an
error in the curvature of the cornea. In the case of nearsightedness the cornea
is more curved than it ought to be as a result it has more focusing power of the
light so when the light hits the cornea it focuses it so much that it falls
short of the back of the eye, short of the retina and the further away that it
falls in front of the retina the more short-sighted that you are and in this
case the distance on the far side will be blurry and this applies in all cases.
So even if it's slightly in front of the retina it will cause a noticeable
reduction in clarity and focus to the person viewing. Now when light falls in
front of the retina there's not much that I can do in response to try and
correct things for you. That's why even a small amount of nearsightedness will
leave somebody quite blurred and on the test chart; roughly about every 0.25
of power we'll lose you about a line on the eye
test chart. Now in the case of farsightedness, this is the situation
when the cornea is flatter than it ought to be as a result it doesn't have enough
focusing power of the light and lightness misses the retina and focus is
long, and focuses behind. Now the further behind the retina that it focuses the
more farsighted are you are. Now in the case of farsightedness the eye does have
a response that means it can compensate through a process that we call
accommodation to allow you to be able to see and get back some of that clarity. it
does this through the second lens in the eye called the crystalline lens. The
crystalline lens can respond to light focusing behind the eye by changing
shape through a process that we call accommodation that then shifts the light
focusing behind the eye further forward and onto the retina as long as it's not
too far behind and not too much work for the lens to have to do, it can do this
and mean then that you can still get good vision and as a result.That's why
people who are farsighted can often find that the term farsightedness
doesn't explain what they're seeing in real world situations. So where as farsight
it's supposed to mean that you have sight for far distances, as a result
you can absorb quite a lot of farsightedness before you start to have
any real problems focusing on objects close up and further away. Now generally
speaking the reason that farsightedness is described as having sight for far
distances and then struggling close up is because accommodation is
really reserved for your focusing power close up. Now when we all come to read or
look at objects close up we get a natural shift of light for backwards
anyway so it falls behind in the eye so that we can focus on objects close up
and in this situation the crystalline lens would normally kick in to
accommodate or adjust for you. If you're really farsighted and the crystalline
lens is having to overcome your farsightedness it then has a huge amount
of extra work to do because it first has to overcome your
farsightedness and then it has to do the normal amount of accommodation that it
needs to do for looking at objects close up and this can often be such a big
workload for the crystalline lens that then people who are farsighted may find
that they struggle seeing close up or their vision and goes blurry
or they get eyestrain just because of the workload that this lens is now under
in order to help you to see objects close up.
So for farsighted people it can be more strenuous on your eyes and looking at
things close up rather than things further away and as a result for the
most part and generally speaking farsightedness is easier on your eye
when you're looking at things further away rather than when you're looking at
objects close up. Now with that in mind you might be thinking why do people with
nearsightedness have the ability to see close up and that's a good question and
it's really for the reason that I mentioned before every time we look at
an object close up we get a natural shift of light backwards. If you're
someone that's farsighted this means that you get a shift of life further
back behind the eye which adds to the workload of the crystalline lens but if
you're someone who's nearsighted you actually get the situation where light
is coming closer to the retina and that actually makes things clearer for you to
see and it may be that this shift of light backwards in the case of
nearsighted people results in the light focusing very close to the retina or on
the retina. In some cases it may even fall behind and in which case the
crystalline lens may be able to help you out with a little bit of accomodation so
you can still see perfectly well. And that's the reason why people who are
nearsighted tend to do very well and may never need reading glasses because at
the point where other people start to have problems with their manual focusing
they will still be able to read and see well close up through most of their life,
and again that depends on how short-sighted or how nearsighted you
are to begin with. So now for my tip of the day... Remember that there's a
difference between being farsighted nearsighted and having presbyopia.
Lots of commentators or bloggers Ioften come across confuse them and often
describe the process of becoming presbyopia, which is the age-related
reduction in your auto focusing ability they confuse that as you growing
farsighted, but you have to keep the terms separated, so farsighted and
nearsighted refers to the impact on the cornea which is the error in how the
cornea is shaped and how light focuses on the retina and presbyopia which is the
error in your auto-focusing ability which affects the crystalline lens further in
from the cornea. Often this leads to the confusion because these commentators are
describing presbyopia as being; you
developing farsightedness when it's not. It may appear like a type of
farsightedness but really you have to think of these things are separate
because they impact a different lens so as I said the cornea is to do with your
farsight and your general vision further away and the crystalline lens is
to do with your auto-focusing ability and seeing things close up to you. So I hope
that makes sense and clears up some of the confusion for you. Now my question
for you today is... What's your biggest challenge when it comes to being
farsighted and nearsighted leave a message for me in the comment section
below also check out the description box for
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Take care!