When Shadows Start to Move : Understanding Myodesopsia

It started with a very tiny black dot. At first, she thought it was just a speck of dust but when she blinked, it moved. She turned her eyes to the other side, it moved again. After few months later, there were more dots and squiggly lines.

Hello doctor, I keep seeing something moving around my eyes and whenever I try to look at it , it moves away from my sight.

Have you ever noticed any tiny black dots, threads, cobwebs or any shadows moving across your vision ? It is the most common symptoms that is encountered by ophthalmologist in the clinics.

These all moving shapes are called FLOATERS aka (muscae volitantes)[Source]

It is so common and so strange if you don't develop floaters during your lifetime. Generally, it is a part of growing older. So any guess about what exactly are floaters ?
To understand it, first we need to look inside the eye. There is a vitreous which is a transparent, gel like substance which lies between lens and retina.

Intact Vitreous gel having maximum water content [Source]

Anatomical visualization of Vitreous [Source]

In the above picture, we can see the green colour coded vitreous. Think vitreous as a 3-D collagen-hyaluronan network. It contains type IX collagen fibrils that provides structural framework whereas Sodium Hyaluronate binds the water and help maintain the gel integrity.

Normal Structure of vitreous (collagen fiber with hyaluronate) [Source]

Hyaluronic acid surround the collagen fibrils and separate them with their negative electrical charges keeping gel transparent and intact.

Let's dive deep into how the vitreous liquefaction or SYNCHYSIS takes place

It refers to tiny collagen fibers clumping together. It can be due to aging, high myopia (nearsightedness), inflammation, posterior vitreous detachment where the shrinking vitreous pulls away from eye wall.

As the collagen fibers become thicker, it clumps together. Additionally, hyaluronan-collagen interaction degrades and forms free water in place of gel matrix. It then forms small pockets and communicates with each other which eventually coalesce and enlarge. Overall vitreous becomes less cohesive. Collagen framework start contracting towards the center called as posterior vitreous detachment.

Posterior vitreous Detachment (PVD) [Source]

PVD occurs when the cortex of vitreous separates from internal limiting membrane of retina. If the traction or contraction is strong enough, it can even contract the retina resulting a retinal tear and detachment.

This is why flashes of light is a warning sign in patient with floaters

[Source]

When the incident light falls on the eye, the condensed collagen aggregates which produces a shadow to the retina and macula. This shadown produce floaters. When you move the eye, the vitreous gel also moves. So, if you try to look at it, it disappers. Generally most of the people don't need treatment as it is harmless. Your brain tries to adapt and ignore floaters, so you probably don't even see them execpt in bright light. However sudden symptoms like

• Flashes of Light
• Loss of peripheral vision
• Falling curtain like vision loss

So if you are not sure what's going on with your vision, it's always better to get checked with an ophthalmologist.

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Reference :

• Adult Vitreous Structure
• Suddenly Seeing floaters ? What's Normal and What needs Attension
• What is Vitreous Liquefation - Blue fin vision
  Other blogs :
• The Cataract That Improved Vision : Second Sight Phenomenon
• A Swollen Disc, A Difficult Decision, A Remarkable Recovery - Papillitis
• Ocular Toxoplasmosis - When Standard Treatment Wasn't Enough

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