Slit lamp

Question 1

What is an alternative name for the slit lamp?

Answer 1

biomicroscope

Question 2

What are 2 benefits of the slit lamp?

Answer 2

1. view is magnified
2. is stereoscopic

Question 3

What does the slit lamp consist of?

Answer 3

binocular compound microscope (2 convex lenses) and adjustable illumination system

Question 4

How are objects brought into focus with the slit lamp and why?

Answer 4

by moving the slit lamp forward or back, because it has a fixed focal plane

Question 5

How is movement of the slit lamp achieved a) laterally b) vertically?

Answer 5

• a) laterally = joystick
• b) vertically = dial attached to the joystick

Question 6

What does the total magnification usually range between in split lamps and what can give a greater range?

Answer 6

• usually 10x to 25x, as some have 2 objective settings (1x and 1.6x) and 2 eyepiece options (10x and 16x)
• others have series of Galilean telescopes that can given 6.3x to 40x

Question 7

What is an alternative, less common way that varying magnification can be achieved with a slit lamp?

Answer 7

zoom system

Question 8

What are the 4 typical illumination filter options on the slit lamp?

Answer 8

1. unfiltered, heat-absorbing filter
2. 10% grey filter
3. red-free filter
4. blue filter

Question 9

What traditionally is used for the blue filter on a slit lamp?

Answer 9

cobalt blue, optionally with a 495nm peak

Question 10

Which slit lamp filter is used for high illumination?

Answer 10

heat-absorbing filter

Question 11

Which slit lamp filter is used for lower illumination?

Answer 11

the grey filter

Question 12

What is the use of the red-free slit lamp filter?

Answer 12

increases visualisation of the vitreous and retinal nerve fibre layer/vasculature

Question 13

What is the blue slit lamp filter used for? 2 things

Answer 13

1. combined with yellow enhancement observational filter to maximise visualisaion of fluorescein
2. blue filter may also assist detection of iron lines

Question 14

What is used to adjust the beam height and width of the slit lamp?

Answer 14

apertures - beam light incremented in milimetres

Question 15

What may the incremental adjustment of the beam light height be useful for?

Answer 15

estimating measurements (e.g. disc size, corneal ulcer etc.)

Question 16

How can the orientation of the slit lamp beam be adjusted from vertical to horizontal, or any other angle?

Answer 16

by swining the superior aspect of the illumination arm to the left or right

Question 17

When is it useful to adjust the orientation of the slit lamp beam?

Answer 17

gonioscopy or measuring lesions

Question 18

How can angulation of the slit lamp beam be achieved?

Answer 18

swinging the whole illumination arm to the side (horizontal) or tilting the illumination arm upward (vertical)

Question 19

Why is it important to be able to adjust angulation of the slit lamp beam?

Answer 19

illumination techniques (direct illumination, retroillumination, sclerotic scatter and specular reflection) require different angulations of the illumination arm

Question 20

What is ‘uncoupling’ with the slit lamp?

Answer 20

illumination arm uncoupled to displace the beam from teh centre of the field of view

Question 21

When might it be useful to tilt the illumination beam of the slit lamp vertically?

Answer 21

may reduce troublesome reflections when using handheld lenses

Question 22

When could it be useful to replace the standard long mirror of the slit lamp with a short mirror?

Answer 22

when using small angulations (3-10 degrees)

Question 23

What are 2 things that may be used as a fixation target in a slit lamp (for patient to fixate on)?

Answer 23

1. standard fixation lamp
2. annular target with focusing range -15 to +10D

Question 24

What is the range of annular fixation target on a slit lamp and why would it be adjusted?

Answer 24

-15 to +10D - adjusted to patient’s refractive error, enabling them to see the target clearly

Question 25

What is a stereoaviator, found on some slit lamps?

Answer 25

changes angle of convergence from 13 degrees to 4.5 degrees

Question 26

What are the benefits of the 13 degree vs 4.5 degreee stereoaviator on slit lamps?

Answer 26

• 13 degrees provides better stereopsis
• 4.5 degrees provides larger binocular field of view and thus improved acuity (binocular acuity > monocular acuity)

Question 27

When might the 4.5 degree stereoaviator setting be useful when using the slit lamp?

Answer 27

for detailed examintion of certain ocular surfaces e.g. corneal endothelium

Question 28

Label 1-15 on the image

Answer 28