Fixation Ophthalmoscopy

Question 1

What are the large/medium/small light source on fixation ophthalmoscopy for?

Answer 1

Ophthalmoscopes usually have 2 or 3 sizes of light to use depending on the level of pupil dilation.

• The small light is used when the pupil is very constricted (i.e. well lit room, no pupil dilators used).
• The medium aperture is the standard for a non-dilated pupil in a dark room
• The large light is best if using mydriatic eye drops to dilate. Most commonly in a dark, non-dilated pupil, the medium sized light is used.

Question 2

What is the half light source on fixation ophthalmoscopy for?

Answer 2

If, for example, the pupil is partially obstructed by a lens with cataracts, the half circle can be used to pass light through only the clear portion of the pupil to avoid light reflecting back

Question 3

What is the red free light source on fixation ophthalmoscopy for?

Answer 3

Used to look at the vasculature.Used to visualize the vessels and haemorrhages in better detail by improving contrast. This setting will make the retina look black and white.

Question 4

What is the slit beam source on fixation ophthalmoscopy for?

Answer 4

Used to examine contour abnormalities of the cornea, lens and retina.

Question 5

What is the blue light on fixation ophthalmoscopy for?

Answer 5

Some ophthalmoscopes have this feature that can be used to observe corneal abrasions and ulcers after fluorescein staining.

Question 6

What is the grid light on a fixation ophthalmoscopy used for?

Answer 6

Used to make rough approximations of relative distance between retinal lesions.

Question 7

How do you use a fixation ophthalmoscopy?

Answer 7

1. Wash your hands.
2. Introduce yourself to the patient and explain what you are going to do.
3. Position the patient so that the ophthalmoscope is held directly at the level of the patient’s eye.
4. Turn on the ophthalmoscope and set the light to the correct aperture.
5. Dim the lights.
6. Instruct the patient to focus on an object straight ahead on the wall.
7. To exam the patient’s RIGHT eye, hold the ophthalmoscope in your RIGHT hand and use your RIGHT eye to look through the instrument.
8. Place your left hand on the patient’s head and place your thumb on their eyebrow.

9.Hold the ophthalmoscope about 6 inches from the eye and 15 degrees to the right of the patient.

10. Find the red reflex.
11. Move in closer, staying nasally until you see the optic nerve.
12. Rotate the dioptre lens until the optic nerve comes into focus.The farsighted eye requires more plus/green number lenses.
    The nearsighted eye requires more minus/red number lenses.
13. Measure the cup to disc ratio.
14. Scan slightly up, down, right and left to look at the vessels.
15. Move out temporally to find the macula and fovea.
16. Repeat the same technique on the other eye

Question 8

What do we need to describe in a Fixation ophthalmoscopy / visuscopy?

Answer 8

• Describe the location
  Central vs eccentric
• Describe the reflex
  Steady or unsteady
• Green filter may help visualisation