Competency 3.1.2

Question 1

Low Mag SL Techniques

Answer 1

• Diffuse illumination
• Optical section
• Parallelpiped
• Sclerotic scatter
• Tangential viewing
• Van Herick’s

Question 2

Medium Mag SL Techniques

Answer 2

• Optical section
• Parallelpiped
• Conical beam
• Retro-illumination
• Specular Reflection

Question 3

High Mag SL Techniques

Answer 3

• Optical section
• Parallelpiped
• Retroillumination
• Specular reflection

Question 4

Definitions of Coupled and Decoupled Systems

Answer 4

• Coupled is when the illumination and observation systems both swing around the same pivot point.
• De-coupled refers to when the illumination system is moved to the side and therefore no longer meets the optimal focus of the observation system.

Question 5

Indirect Illumination SL Techniques

Answer 5

• Retro-illumination
• Sclerotic scatter

Question 6

Optical Section SL Technique

Answer 6

• Very thin beam
• Images a section of cornea or lens
• Must be at 90 degrees to the corneal surface
• Variable magnification

Question 7

Parallelpiped SL Technique

Answer 7

• Slightly broader beam than optical section (avg width 1mm)
• Variable angle of illumination system
• Can be used to assess how flat conjunctiva is and can be used to visualise SPK

Question 8

Conical Beam SL Technique

Answer 8

• Circular beam and medium magnification
• Illumination system positioned temporally 45 to 60 degrees
• Observation system remain central
• Observe the space between lens conical section and corneal conical section for cells
• Avoid hitting iris to allow for darkest environment

Question 9

Grading of Anterior Chamber Activity

Answer 9

Measured in a 1x1 conical beam
- Grade 0 (None) - No cells in field
- Grade 1 (Faint) - 6 to 15 cells
- Grade 2 (Moderate) - 16 to 25 cells
- Grade 3 (Marked) - 26 to 50 cells
- Grade 4 (Intense) - Over 50 cells

Question 10

Tangential SL Technique

Answer 10

• Employed to observe iris
• Illumination system is swung out to almost a right angle
• Observation system remains infant of patient
• Raised lesions viisble as shadows

Question 11

Specular Reflection SL Technique

Answer 11

• Illumination and observation systems at an equal angle to the normal of the area of cornea which you wish to assess
• Move the corneal section onto a purkinje image, causing hyper illumination of epithelium and endothelium
• Zone into less luminous endothelial layer

Question 12

Retro-Illumination SL Technique

Answer 12

• Decouple systems when looking through pupil to allow for assessment of lenticular opacity using red reflex

Question 13

Sclerotic Scatter SL Technique

Answer 13

• Create a corneal section then decouple the illumination so it illuminated the limbus
• TIR occurs within cornea
• Any faint corneal lesions will scatter light allowing for detection

Question 14

Cobalt Blue SL Filter

Answer 14

• Enhances view of NaFl dye

Question 15

Red-Free SL Filter

Answer 15

• Appears green
• Enhances appearance of vessels and haemorrhages

Question 16

Neutral Density SL Filter

Answer 16

• Colourless/grey filter
• Reduces illumination for photosensitive patients

Question 17

Wratten 12 SL Filter

Answer 17

• Yellow filter
• Improves ability to visualise NaFl lesions
• Useful to aid contrast in RGP fit

Question 18

Van Hericks SL Technique

Answer 18

• 60 Degree angle between illumination and observation
• Patient needs to be looking towards the illumination system
• Conducted nasally and temporally

Question 19

Van Hericks Technique Grading

Answer 19

VHG4 (wide open) - gap is size of corneal thickness
VHG3 (Open) - half the size of corneal thickness
VHG2 (Narrow) - quarter size of corneal thickness
VHG 1 (extremely narrow) - Less than quarter of corneal thickness