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Slit lamp skills

Practitioners will recognise that using a slit lamp soon becomes second nature as the textbook approach to the various techniques fade into a distant undergraduate memory.  This VRICS feature revisits the principles behind the basic techniques of slit lamp examination.

Image A


01 What is the correct term for the slit lamp technique being used?

a) Diffuse illumination
b) Retro illumination
c) Optic section
d) Specular reflection

02 Which statement regarding this technique is correct?

a) It is a form of direct (focal) illumination
b) The angle of illumination must not exceed 60 degrees
c) Magnification should be kept low
d) Reducing the angle of illumination makes it easier to distinguish between the individual layers of the cornea

03 Apart from the cornea, which other ocular structure is this slit lamp technique most often used to examine?

a) Iris
b) Crystalline lens
c) Anterior vitreous
d) None of the above

Image B


04 What is the name of the technique being used to assess the anterior chamber?

a) Schaeffer’s method
b) Smith’s method
c) Conical beam
d) van Herick’s technique

05 Which statement regarding this slit lamp technique is correct?

a) The angle of illumination should be set to 45 degrees
b) The slit width should be at least 2mm
c) It is used to quantify the depth of the anterior chamber
d) Taking measurements away from the limbus will overestimate the width of the anterior chamber angle

06 In which of the following is assessment of the anterior chamber angle indicated?

a) Normal tension glaucoma
b) Pigmentary glaucoma
c) Neovascular glaucoma
d) All of the above

Image C


07 What is the name of the technique being used?

a) Parallelepiped
b) Specular reflection
c) Retro illumination
d) Sclerotic scatter

08 Which statement regarding the technique shown is false?

a) It is preferable to perform this technique with the illumination and observation systems of the slit lamp decoupled
b) The angle of illumination should be less than 45 degrees
c) A healthy cornea will appear dim with a halo of light around the limbus
d) This technique uses the principle of total internal reflection

09 Which condition is least likely to be detected using this technique?

a) Central corneal clouding
b) Map-dot fingerprint dystrophy
c) Pseudoexfoliation syndrome
d) Post-herpetic corneal scarring

Image D


10 What is the name of the slit lamp technique being used to investigate the cornea?

a) Specular reflection
b) Sclerotic Scatter
c) Diffuse illumination
d) Retro illumination

11 Which statement in relation to this slit lamp technique is false?

a) Magnification should be set to high (~40X)
b) It is a monocular technique
c) The angle of incidence is equal to the angle of reflection
d) The third Purkinje image is visible in Image D

12 Which structure is this technique least likely to be used to examine?

a) Tear film
b) Anterior lens surface
c) Corneal endothelium
d) Anterior chamber

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