Van Herick Technique

Question 1

Two main types of beams

Answer 1

Direct diffuse

Direct focal: Parallelpiped or optic section

Question 2

Two techniques to assess angle of anterior chamber

Answer 2

Van Herick, shadow technique.

Question 3

When to use the diffuse beam

Answer 3

Used to illuminate and observe large gross areas of eye. Low magnification, not focused on any structure.

Ex: See if the eye is red

Question 4

Direct focal illumination: Parallelpiped

• Beam?
• Observe what?
• Beam width
• Mag?
• beam height?
• illumination?

Answer 4

Narrow beam (2mm) that is at a 45-60 degree angle and full length in height.
Observe 3D quality of the cornea
Magnification at 10x and illumination moderate

Question 5

Direct focal illumination: Optic section

• Angle
• mag
• illumination
• beam width
• beam height
• Observe what?

Answer 5

45-60 degree angle 
Moderate to high mag- 16x 
High illumination
Narrowest beam possible
Full beam height 
Can show corneal edema, thinning, and can be used to assess anterior chamber angle or evaluate lens

Question 6

Which technique do you use to assess anterior chamber angle?

Answer 6

Optic section. Angle must be 60 degrees

Question 7

Which technique do you use to assess the lens, corneal edema or thinning?

Answer 7

Optic section

Question 8

Van Herick

• What technique
• Angle?

Answer 8

Optic section

must be 60 degrees

Question 9

What three things are you looking at/comparing during the assessment of anterior chamber angle?

Answer 9

Corneal thickness, chamber angle, then slit on iris.

Question 10

Grade 4 Van Herick

Answer 10

1:1 ratio between corneal thickness and anterior chamber

Question 11

Grade 3 Van Herick

Answer 11

1: 1/2 ratio. Anterior chamber is half the width of the corneal thickness.

Question 12

Grade 2 Van Herick

Answer 12

1: 1/4 ratio. Anterior chamber is 1/4 the width of the corneal thickness. At this point, you should prob use gonio lens to check the angle. Dr. Heard says she dilates these pts all day

Question 13

Grade 1 Van Herick

Answer 13

1: less than 1/4 ratio. Anterior chamber is less than 1/4 the width of the corneal thickness. Ask if pt is in pain? Use gonio. May close with pupil dilation.

Question 14

Tx of choice for closed angles

Answer 14

Laser iridotomy

Question 15

Grade 0 Van Herick

Answer 15

1:0. No space between optic section and iris. Scary.

Question 16

How to assess anterior chamber angle with pen light

Answer 16

Hold pen temporally and shine towards pts nose.

• No shadow? Grade 4
• Slight shadow nasally (furthest away from light) grade 3
• Shadow half way? Grade 2
• Shadow mostly everywhere except where light is directly shining? Grade 1

Question 17

Are angles symmetric between eyes?

Answer 17

Yes! Count on it. If they are not symmetric, weird.
Ex: OD 4/3 OS 3/4
Temporal G4, nasal G3.

Question 18

Tonometry settings

• Filter?
• Angle?
• Mag?
• Beam height/width
• Illumination/

Answer 18

• Blue cobalt filter
• 45-60 degree displacement
• 10x or 16x mag
• Widest/hightest beam
• Highest level illumination

Question 19

Gonioscopy settings

• Filter?
• Technique?
• Illumination
• Angle?
• Mag?

Answer 19

White light 
Vertical parallelepiped narrow beam
Moderate illumination
Click stop
Moderate mag 10-16x

Question 20

Non contact fundus exam settings

• Filter
• Angle
• Technique
• Illumination
• Mag?

Answer 20

white light 
click stop
Parallel pipped (moderate width and height inside pupil) 
Low to medium illumination
Low mag 10x