h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Posterior Vitreous Detachment - A48379206
Author: BigAl. Keeper of the Glowing pickle and monobrows. Patron Saint of Left Handers - U723247

Description of my recent eye operation

Thanks for writing this, Al.

I've been warned that I'm susceptible to this condition, as I'm quite short-sighted, and reading your account will help me cope with this should it ever happen.

I guess you'll update this in due course as you continue to make a full recovery.

Nice to see some humour in the Edited Guide, even if it is vitreous.

Icy

Terrific!
I see lots of patients who've had this done, very interesting to hear the patient's perspective.

Picked up one typo - sudden impairment 'along'

I would query the statement that floaters will eventually sink out of sight - perhaps change to 'tend to'. Plenty of people complain about persistent floaters with PVD. Following on from that, whereas retinal detachment makes surgery necessary, floaters by themselves do not. Given the risk of any surgery, the impairment from floaters would have to be fairly severe to consider it.

I don't understand how you say that the flashes of light are caused by the vitreous humour detaching itself from the retina, but you also say it's not attached to the retina except in three places.

Hi Gnomon,

Well, the flashes of light are caused from the 3 places where the retina IS attached to the chorion.

Oh, I see what you mean. Although the vitreous humour is not attached (i.e. 'glued' to the retina, it is still in close physical contact; enough to cause static electricity as the two surfaces separate.

A

Hi TS.I've wondered from your Entries whether you were professionally involved, or a 'victim'.

I'll make some mods in the light of your comments.

A

Modifications made in the light of comments from Teaswill and Gnomon

Hey, TS, a Q you may be able to answer:

Ref, 'Floaters are more evident if one stares at a pale or blue surface such as a wall or the sky.'

My opyician once tols me that this has a name, 'Somebody's Effect'

My recollection is that the 'somebody' sounded s'thing like Gangefeldt. I've tried Googling this but to no avail Any ideas

"help to refract light and produce an image on the retina"

That's the job of the lens - the aqueous and vitreous are there to provide a clear medium.

"The flashes of light occur when the vitreous humour pulls on the sensory layer of the retina, as the vitreous is detaching."

It's worth mentioning that these flashes occur as the mechanical force of the vitreous pulling on the retina is transformed into nerve signals, which are then interpreted as light by the brain.

"where the shape of the eyeball is elongated from front to back"

...thus putting more strain on the vitreous.

"A PVD can also occur after injuries to the eye or inflammation in the eye (uveitis)."

It is also more likely to occur following a cataract operation.

"This will enable fluid to seep seep between the"
seep seep --> seep

"Sudden (slight) impairment alonfg with light flashes and increase in the number of floaters."
alonfg --> along

"A veil or curtain, that crosses the eye from any direction, that obstructs all or part of your field of vision."

It's worth adding a footnote stating that this may be a result of both retinal detachment and of amaurosis fugax, in which a transient ischaemic attack ('mini stroke') produces a descending curtain that clears again within minutes of the attack. Amaurosis fugax also requires urgent attention.

"will sink below the line of sight and so become invisible."
These floaters may still be visible after rapid eye movements or after lying flat for some time, but they generally aren't a problem.

"a cutting device to cuts through and removes the vitreous humour,"
-->
"a cutter/suction device that cuts through and removes the vitreous humour"

"The vitreous humour may be replaced either with air or a gas, which is absorbed and replaced naturally with isotonic fluid (aqueous humour) over about 2 weeks; or with silicone oil. Silicone oil is not absorbed and has to be removed surgically at a future date."

These aren't replacement fluids! Saline is used to replace the vitreous, and the gas/oil bubble is inserted so that it pushes against the reattached segment of retina, holding it in place while scarring and healing occur.

You are right, though, in saying that gas is absorbed whereas oil must be removed.

"potential complications include post-operative, bleeding, infection"
infection --> serious infection
(eye infections are sight-threatening and can spread to the brain)

"'Maxidex, also known as dexamethasone"
--> "Dexamethasone (trade name 'Maxidex')"

"Patients who have had the vitreous humour replaced with air or gas are advised to avoid flying, as the reduced atmospheric pressure causes the gas bubble to expand, thus raising the pressure in the eye to perhaps dangerous levels."

Again, the bubble is not a replacement. Also, you might note that the increased intraocular pressure caused by flying with an air bubble can prevent blood from reaching the retina and thus blind the recovering patient.

That's all for now

Alex

I've seen to all that Alex. Some good points. I'll give yoiu a CREDIT for Additional Research >ok>

Might be Scherer's Phenomenon? (I had to look it up!)
It's when you see against eg the sky/ white wall flashing dots along the route of blood vessels.

Also
sp - should be 'haemorrhage'

'jelly' is unneccessary, just 'vitreous' will do.

no comma needed - 'post-operative bleeding'

apostrophe needed 'one's'

sp 'experienced'

Might be worth adding that it can be difficult to establish a stable spectacle correction for patients with silicon oil.

Done those, TS - except for <'jelly' is unneccessary, just 'vitreous' will do.>

I know that's how leaflets/websites use it but, to me being a purist, 'vitreous is an adjective, not a noun

I looked up Scheerer's Phenomenon, TS, only to discover that it's a perfectly normal visualisation of WBC's against a blue background. However, it was being able to see this when looking down a microscope that first alerted me to the floaters. So, I'd better make no mention of this in my Entry

Wishing you continued recovery Al.

My floaters seem to be worse when I'm tired or stressed, and definitely more obvious agasint a pale unpatterned background.

Having had laser eye surgery, I sypmathise with the having eyes open during surgery bit!

Are they the black floaters you're referring to Bea?. If so, I may put the bit abput the blue background back in.

My 'Scheerer's Effect' was of hundreds (literally the whole of my field of vision) of tiny translucent spheres passing in one direction across my field of vision. Having now read up on Scheerer's, I now understand these to be white blood cells - and is perfectly normal (hmm).

When I first experience 'em, it coincided with my having the sensation of slightly impaired vision, i.e. my spectacles smeared with s'thing greasy. I kept taking 'em off to try and clean, butr the were perfectly clear already.

It seemed logical at the time that the smearing effect and the translucent spheres were 'effect and cause'.

My first experience of floaters was when I used to waer soft contact lenses, and I assumed it was a hole in one of the lenses!

Grey, rather than black. But 1 or 2, not hundreds of.

I'll wait to see if Teasswill comes back...

"Floaters may result from
normal vitreous composition, as seen with
muscae volitantes or from white blood cells
flowing through the retinal blood vessel
(Scherer’s phenomenon). They may also
result from, and must be differentiated from,
floaters that occur from an inflammation,
retinal detachment (Shafer’s sign or tobacco
dust) or posterior vitreous detachment"

A straight lift from a professional journal.