Page 1 of 1: Glaucoma...

parin · Credits: 14530 My Scrapbook My Reading List 1 Books

Hi friends! Here is some mcq-information about glaucoma from standard textbooks...

Tonometry:

There are 2 types of tonometry:

Indentation tonometry uses Schiotz tonometer. The principle being a plunger will indent a soft eye more than a hard eye..

The footplate can be sterilized by dipping in ehter, absolute alcohol, acetone or by heating the footplate in the flame of spirit..

It has greatest accuracy when the deflection of the liver is b/w 3-4.

The main disadvantage is it gives false results in eyes with abnormal scleral rigidity..

The causes of low scleral rigidity are dysthyroid exophthalmos, high myopia, eyes treated wiht miotics, eyes that have been subjected to surgery...

Applanation tonometry is based on Imbert-Fick low-for an ideal, dry, thin-walled sphere the pressure inside the sphere(P) equals the force necessary to flatten its surface(F) divided by the area of flattening(A).. P=F/A

6 Applanation tonometers are used:

The Goldmann tonometer gives the most accurate results.. It consists of a double prism that has diameter of 3.06 mm. when stained with fluorescein & a cobalt blue filter is used, two yrllow semicircles are seen, inner edges of two semicircles will just touch when the cornea has been perfectly flattened..

At the diameter of 3.06 mm, resistance of cornea & capillary attraction of the tear meniscus tending to pull the tonometer towards to cornea cancel each other..

The Perkins hand-held tonometer uses a Goldmann prism adapted to a small light source.. The main advantage being usefulness in supine posion, so can be used in bed-bound & anaesthetized patients..

The pneumatonometer measures IOP by indenting the cornea by a grade dflow of gas against a flexible diaphragm..

The 'air-puff' tonometer uses the Goldmann principle, but the central part of the cornea is flattened by a jet of air.. light is then reflected from the flattened corneal surface to a photoreceptor which is activated to turn the air off. The time required to sufficiently flatten the anterior cornea relates directly to the level of IOP. The main advantages being a local anaesthetic is not required & no r/o spreading infection from one pt to another..

The Mackay-Marg is a portable electronic tonometer with an action that can be considered as lying b/w the indentation & applanation principles.. It measures the force required to flatten a small area of cornea against a 1.5 mm plunger protruding 5 microm beyond the surface footplate. It can be uesd on scarred or irregular corneas..

The microelectronic Tono-Pen has principle similar to the Mackay-Marg tonometer. There is a microscopic strain-gauge transducer that applanates the cornea, cpnverting IOP into electrical waves. The area of applanation surface is small allowing increased accuracy in measuring IOP after keratoplasty, radial keratotomy & irregular astigmatism..

parin · Credits: 14530 My Scrapbook My Reading List 1 Books

Sorry friends! This ooist has been posted thrice because of technical problems..

mini_med · Credits: 1927 My Scrapbook

hi. im not as experienced as u are. but is this enough regarding glaucoma?

mini_med · Credits: 1927 My Scrapbook

hi. im not as experienced as u are. but is this enough regarding glaucoma?

mini_med · Credits: 1927 My Scrapbook

oh im sorry.the rest of it is in the other post.i hadn seen it.saw it now.... thanks for ur notes that are posted here.im finding it ncie. sure it will be helpful..

mini_med · Credits: 1927 My Scrapbook

oh im sorry.the rest of it is in the other post.i hadn seen it.saw it now.... thanks for ur notes that are posted here.im finding it ncie. sure it will be helpful..

parin · Credits: 14530 My Scrapbook My Reading List 1 Books

dear mini_med,

it's nice my posts are helpful.. but I always believe, nothing is enough in medicine!!

mini_med · Credits: 1927 My Scrapbook

thats right.medicine is never ending.im sitting with ophthal book since mornin and its goin so slowly...

haysamon · Credits: 240 My Scrapbook

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