The Normal Eyelid anatomy.
Why is it important for YOU to know what is normal?
Be Empowered through understanding
Hi, I'm Dr Colin Parsloe. I consider myself to be a Professional patient - I work as an Ophthalmologist but live with Dry Eye Disease. I have been studying, treating and teaching on Dry Eye Disease for many years.
After finishing this complete video: You will have the core knowledge you need to understand what Dry Eye Disease is and how best to treat it.
When I found out that I had Dry Eye Disease in 2006, I fortunately already had a good understanding of the eyelids as I was in my final years of training as an Ophthalmologist.
This has helped me to understand why I get Dry Eye Disease. Also I understand why and how best to treat it.
I have found that when I have taken the time to explain some core pieces of anatomy to others with Dry Eye Disease (My Champion patients) they perform the treatments better and stick to it longer.
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What we will cover: we are going to briefly look at the components of the eye, eyelids and the tear film.
Our online course is focussed on taking you from a point of minimal understanding of Dry Eye Disease to a good core knowledge - as quickly as possible but without missing too much of the key points.
I do a 2 day training for corneal specialist ophthalmologists on this condition and I have tried to distil it into a 2 hour course.
I really fo hope that you find the content valuable.
So, what are the parts of the eye called?
This is the front surface of the eye, the clear window through which we see. It must be kept moist at all times to remain transparent. During cataract surgery when a patient can’t blink there is usually a junior doctor sitting there with the sole purpose of putting regular drops onto the eye that is being kept open. This is in order to keep the ‘window’ clear so we can perform the surgery.
These are very cleaver muscular parts of the body that can respond in an instant to close and to protect the eye. I find it fascinating that it is nearly impossible to keep the eyes open during a sneeze! They have a protective cartilage shield like layer which contains some very important glands, the Meibomian Glands.
These crucial glands produce the oil (Meibum) that is so important to a healthy tear.
Deep under the eyelids are the main water reservoir the lacrimal gland. It is critical to a healthy tear film. There are certain diseases that target this gland and can cause some of the worst cases of Dry Eye Disease. These fall under the heading of Sjögrens disease. See other LM.
Goblet cells are tiny goblet shaped cells in the transparent layer (Conjunctiva) that covers the white of the eye. They get damaged and reduce in number with Dry Eye Disease.
What are all the structures of the tear film and where do they come from?
Key components are the gel layer and an oil coating of the surface of this gel.
We used to think of a tear as a watery layer with a thin film of gel over the very surface of the eye. Now we think of it more like a thick gel.
I had always marvelled at how water could stick to the vertical surface of the eye, it is much easier to think of it as a thick gel sticking to the eye.
The part of the gel closest to the eye actually has parts that project into the front surface of the eye - anchoring the gel there. The part of the gel furthest from the eye is more watery but there is no specific clear watery layer.
Problems with the oil layer - This is called Meibomian Gland Disease and is the leading cause of Dry Eye Disease.
Where do the tear components come from?
The muco-aqueous gel layer is a very dynamic layer and has to keep its shape and structure during blinks and we believe that it looks different and behaves differently when you sleep.
Mucins, the gel forming components, come from the goblet cells.
Aqueous comes from water producing glands under the eyelids and from the large water reservoir the lacrimal gland.
This comes from the oil producing glands in the eyelids.
The Meibomian Glands
Tears also contain many proteins and other component that have numerous roles including anti-inflammatory and antibiotic roles.
Tears constantly wash over the surface of the eye from the outer part of the eye (part nearest your ears) across and down towards your nose. Then they leave through two small holes (puncti) and drain into the back of your throat. One way of treating Dry Eye Disease is to put ‘plugs’ into the small openings.
Stable tears - How long does a tear last for?
Now for most healthy people they can keep their eyes open for 20 seconds or longer before the tear film coating the surface of the eye breaks up. So if they are engaged in an activity requiring their attention such as reading or watching a crime thriller and they only blink once every 20 seconds they will have no problems.
For those of us with Dry Eye Disease our tears break up in less than 10 seconds. So if we only blink once every 20 seconds doing a task such as working on a computer, watching TV or reading; Then our eyes will only be covered by a healthy tear film for less than half of that time.
In other words we would have large dry patches over our eyes for more than half of the time we are doing these tasks.
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