● Darken the room. Switch on the ophthalmoscope light and turn the lens disc until you see the large round beam of white light.* Shine the light on the back of your hand to check the type of light, its desired brightness, and the electrical charge of the ophthalmoscope.
● Turn the lens disc to the 0 diopter. (A diopter is a unit that measures the power of a lens to converge or diverge light.) At this diopter, the lens neither converges nor diverges light. Keep your finger on the edge of the lens disc so that you can turn the disc to focus the lens when you examine the fundus.
● Hold the ophthalmoscope in your right hand and use your right eye to examine the patient's right eye; hold it in your left hand and use your left eye to examine the patient's left eye. This keeps you from bumping the patient’s nose and gives you more mobility and closer range for visualizing the fundus. With practice, you will become accustomed to using your nondominant eye.
● Hold the ophthalmoscope firmly braced against the medial aspect of your bony orbit, with the handle tilted laterally at about 20° slant from the vertical. Check to make sure you can see clearly through the aperture. Instruct the patient to look slightly up and over your shoulder at a point directly ahead on the wall.
● Place yourself about 15 inches away from the patient and at an angle 15° lateral to the patient's line of vision. Shine the light beam on the pupil and look for the orange glow in the pupil—the red reflex. Note any opacities interrupting the red reflex.
Fig.1
Examiner at 15-degree angle from patient's line of vision, eliciting red reflex.
● Now place the thumb of your other hand across the patient's eyebrow, which steadies your examining hand. Keeping the light beam focused on the red reflex, move in with the ophthalmoscope on the 15° angle toward the pupil until you are very close to it, almost touching the patient's eyelashes and the thumb of your other hand.
● Try to keep both eyes open and relaxed, as if gazing into the distance, to help minimize any fluctuating blurriness as your eyes attempt to accommodate.
● You may need to lower the brightness of the light beam to make the examination more comfortable for the patient, avoid hippus (spasm of the pupil), and improve your observations.
*Some clinicians like to use the large round beam for large pupils, and the small round beam for small pupils. The other beams are rarely helpful. The slitlike beam is sometimes used to assess elevations or concavities in the retina, the green (or red-free) beam to detect small red lesions, and the grid to make measurements. Ignore the last three lights and practice with the large or small round white beam.
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