Van Herick Technique Flashcards

1
Q

Two main types of beams

A

Direct diffuse

Direct focal: Parallelpiped or optic section

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2
Q

Two techniques to assess angle of anterior chamber

A

Van Herick, shadow technique.

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3
Q

When to use the diffuse beam

A

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

Ex: See if the eye is red

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4
Q

Direct focal illumination: Parallelpiped

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

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

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5
Q

Direct focal illumination: Optic section

  • Angle
  • mag
  • illumination
  • beam width
  • beam height
  • Observe what?
A
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
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6
Q

Which technique do you use to assess anterior chamber angle?

A

Optic section. Angle must be 60 degrees

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7
Q

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

A

Optic section

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8
Q

Van Herick

  • What technique
  • Angle?
A

Optic section

must be 60 degrees

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9
Q

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

A

Corneal thickness, chamber angle, then slit on iris.

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10
Q

Grade 4 Van Herick

A

1:1 ratio between corneal thickness and anterior chamber

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11
Q

Grade 3 Van Herick

A

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

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12
Q

Grade 2 Van Herick

A

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

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13
Q

Grade 1 Van Herick

A

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.

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14
Q

Tx of choice for closed angles

A

Laser iridotomy

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15
Q

Grade 0 Van Herick

A

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

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16
Q

How to assess anterior chamber angle with pen light

A

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
17
Q

Are angles symmetric between eyes?

A

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

18
Q

Tonometry settings

  • Filter?
  • Angle?
  • Mag?
  • Beam height/width
  • Illumination/
A
  • Blue cobalt filter
  • 45-60 degree displacement
  • 10x or 16x mag
  • Widest/hightest beam
  • Highest level illumination
19
Q

Gonioscopy settings

  • Filter?
  • Technique?
  • Illumination
  • Angle?
  • Mag?
A
White light 
Vertical parallelepiped narrow beam
Moderate illumination
Click stop
Moderate mag 10-16x
20
Q

Non contact fundus exam settings

  • Filter
  • Angle
  • Technique
  • Illumination
  • Mag?
A
white light 
click stop
Parallel pipped (moderate width and height inside pupil) 
Low to medium illumination
Low mag 10x