|How to use a direct ophthalmoscope|
The direct ophthalmoscope is a useful
tool but often under utilized by
non-ophthalmologists. The following steps will help the doctors to obtain
a good fundal view provided the patient has clear media ie. without
corneal, lens or vitreous opacities.
1. To examine the right eye, sit or stand at the patient's right side.
2. Select "0" on the lens disc of
the ophthalmoscope and start with
the small aperture.
3. Hold the ophthalmoscope vertically
in the right hand and placed it in
front of your right eye with the light beam directed toward the patient .
Place your right index finger on the edge of the lens dial so that you may
change lenses easily if necessary.
4. Dim room lights. Instruct the
patient to look straight ahead at a distant
object. (If the patient looks at the light or focus on near object, the pupil
will constrict due to accommodation making examination difficult.)
5. Position the ophthalmoscope about
6 inches (15 cm) in front and slight to
the right (250) of the patient and direct the light beam into the pupil.
A red reflex should appear as you look through the pupil. (Absence of red
reflex occurs in dense cataract or scarred cornea)
6. While the patient is fixating
on the specified object, keep the reflex in view
and slowly toward the patient. The optic disc should come into view
when you are about 11/2 to 2 inches (3-5cm) from the patient. If it is not
focused clearly, rotate lenses with your index finger until the optic disc is
as clearly visible as possible. The hypermetropic eye requires more plus
lenses for clear focus of the fundus; the myopic eye require minus lenses
for clear focus.
7. Now examine the disc for clarity
of outline, colour, elevation and condition
of the vessels. Follow each vessel as far to the periphery as you can.
To locate the macula, focus on the disc, then move the light approximately
2 disc diameters temporally. You may also have the patient look at the light
of the ophthalmoscope, which will automatically place the macula in full view.
Look for abnormalities in the macula area. The red-free filter facilitates
viewing of the centre of the macula.
(If the patient presents with visual loss:8. to examine the extreme periphery, instruct the patient to:
a. examine the disc for swelling: seen in anterior ischaemic optic neuropathy;
central retinal vein occlusion
b. examine the vessels for:
c. examine the retina for:
- tortuosity and dilatation seen in central retinal vein occlusion;
- narrowing of the vessels in central retinal artery occlusion
- paleness in retinal artery occlusion
- haemorrhages in retinal vein occlusion; diabetic retinopathy.)
a. look up for examination of the superior retina
b. look down for examination of the inferior retina
c. look temporally for examination fo the temporal retina
d. look nasally for examination fo the nasal retina.
Steps 7 and 8 will reveal almost any abnormality that occur in the fundus.
(Note: in patients who complain of sudden onset floaters, direct ophthalmoscope may notBack to eye examination
give enough periphery view to locate peripheral tear or hole and referral is recommended
especially if you notice any retinal haemorrhages.)
Tips for better fundal view
1. Corneal reflection can interferes with fundal view.
If this is troublesome, this can be overcome with:
2. Small pupil especially in the elderly. Use of short acting dilating drops can
- use the polarized filter found in some ophthalmoscope
- small aperture but this reduces the area of the fundus illuminated
- direct the light toward the edge of the pupil rather than directly through
increase the area of the fundus examined. The most effective combination
is tropicamide 1% and phenylepherine 2.5% as they acts on different iris
muscle. If you can only use one dilating drop instil tropamide which dilate
the pupil more efficiently than phenylepherine.