Gonioscopy Flashcards
An examination of the eye to look at the anterior chamber from the anterior part of the iris to the posterior part of the cornea using the helps of a goniolens and a slit lamp
Gonioscopy
Order of the angle
CB
scleral spur
TM
Schwalbes line
All the emergent light is subjected to
The total internal reflection
Why is the angel hard to see without a gonio
Because the region is covered by a projecting shelf of sclera at the limbus
Why use gonioscopy
- fundamental part of a comprehensive eye exam
- most important factor in differential diagnosis (COAG vs angle closure glaucoma)
- done on ALL glaucoma suspects
- repeat periodically for narrow angle or angle closure glaucoma patients
What is the most important factor in differential diagnosis for glaucaom
Gonio
All four mirrors on the lens is an angle of ______
64 degrees
-eliminates the need for rotating the lens
Posterior curvature of the lenses of a goniolens (4 mirrors)
Posterior curvature of all these lenses are equal to that of the cornea which allows the patients own tear film to form the “fluid bridge” between the lens and the surface of the cornea
Purpose of 3 mirror gonio
Use this for more than gonioscopy. Can look at different parts of the retina too. Look at retina that us closest to ciliary body and the other two mirrors go a little further back into the peripheral retina
Apical mirror of 2 lens
D shaped
- only one that you can use for gonioscopy
- put it on the superior part of the cornea to see the inferior angle
Peripheral mirror in a 3 lens
Goes towards the periphery of the retina
-look at the anterior retina
Equatorial lens of the 3 mirror
Looking at the equator of the eye
From posterior to anterior, what structure should you see in the gonioprism
Ciliary body
Scleral spur
TM
Schwalbes line
How to remember the 3 differnt lenses on 3 lens
APE
Apical
Peripheral
Equatorial
How to remember gonio structures
I CANT SEE THIS STUFF I-iris C-ciliary S-scleral spur TM Schwalbes line
Deepest angle
Inferior angle
Most pigmented angle
Inferior angle
Most important angle to look at during gonio
Inferior
What mirror will you look at to view the inferior angle
The superior (12 0c lock) one
Looking over the hill
- iris is bowed, hard to see over it
- move the mirror over towards the angle you are looking at and it will take you up over the hil (over the iris)
How to move the mirror to look over the hill
Towards the angle you are trying to view
Difficult angles
Go to the other eye
-most patients have symmetrical eyes
Doing a peripheral iridotomy in one eye
You will have to do the other eye
A good screening tool before gonio
Von Herrick
Do it in all 4 meridians
In van Herrick, the beam is offset ____ temporally to the slit lamp ocular
60 degrees
If the anterior chamber depth is as deep as the cornea is thick,
Then the angle is presumed to be wide open
Good screening tool before gonio
Von herrick
If you cant see anything in one eye on gonio
Look at the other eye, also compare to van Herrick
Van herrick grading
4 wide open
Can’t see any light- 1
Normal vessels in the angle
- radial orientation (not branching)
- thick
- non-breaching
- do NOT cross the scleral spur
Neovascularization in the angle
- fine
- arborising
- crosses scleral spur
Corneal wedge
When a thin slit of light hits the irido-corneal angle at an angle of 10-15 degrees
- two light reflections are seen from the external and internal corneal surfaces which pipe down at the scleral corneal junction (schwalbes)
- this marks the anterior border of the TM
Indentation gonioscopy
Ver useful in patients where the iris covers the TM. When that happens, it is easy to mistake
- no pigmented TM for scleral spur
- pigmented schwalbes line for TM
- apposition for synechiae
Indentation gonioscopy in glaucoma
Push down on the cornea
Helps open the angle up a little bit so you can see down into there
Indentation gonioscopy and synechiae
Won’t be abale to break synechiae with this. But you can see it
Plateau iris
Need to use indentation gonioscopy to see the angle
Scleral spur visible
Yes, grade angle, record findings
Open angle
Scleral spur is not visible
-do indentation gonioscopy
When doing indentation gonioscopy when you dont see the scalers spur, and you see synechiae
Grade angle
Record findings
Primary angle closure (synechiae)
If you do not find synechiae upon indentation gonio
Check to see is IOPs are raise
- yes: grade angle, record findings, primary angle closure, primary angle closure
- no: grade angle, record findings, primary angle closure suspect
