The ophthalmoscope is a handheld diagnostic device used to view the interior structures of the eye, a procedure known as ophthalmoscopy or fundoscopy. It projects a beam of light through the pupil to illuminate the fundus, which includes the retina, optic disc, and blood vessels. A precise examination is necessary for detecting early signs of conditions like diabetes, hypertension, and various eye diseases. Proper technique ensures the examiner obtains a clear, magnified view of the posterior segment of the eye.
Preparing the Device and Environment
Before beginning the examination, the environment must be adapted to promote a clear view of the fundus. Dimming the room lights encourages the patient’s pupils to dilate naturally, providing a larger viewing window into the eye. The patient should focus their gaze on a distant, fixed point, such as a spot on the wall. This fixation prevents eye movement and facilitates the viewing of the optic disc.
The ophthalmoscope requires several adjustments. The light beam should be set to the medium-sized aperture, which is typical for a non-dilated pupil in a darkened room. This setting balances light intensity and minimizes glare. The diopter wheel, which adjusts the focus, should be set to zero or a position that corrects for the examiner’s own refractive error. The instrument should be turned on and the light intensity set to a bright level.
Mastering the Hand Position and Stance
The physical position of the examiner and the way the ophthalmoscope is held are fundamental to a successful examination. The examiner must always use the hand and eye that are on the same side as the patient’s eye being examined. For example, to examine the patient’s right eye, the examiner holds the ophthalmoscope in their right hand and looks through the viewing aperture with their right eye.
The device should be held firmly, with the handle resting in the palm, similar to a hammer grip. The viewing aperture should be pressed close to the examiner’s brow bone. This technique ensures the ophthalmoscope moves in unison with the examiner’s head, keeping the light beam stable and centered on the pupil. The examiner should position themselves slightly to the side of the patient, approaching at an angle of about 15 to 45 degrees temporal to the patient’s line of vision.
The free hand serves a stabilizing function. This hand is placed gently on the patient’s forehead or shoulder to brace the instrument and prevent accidental contact between the examiner’s face and the patient’s. The thumb of this stabilizing hand can also be used to gently lift the patient’s eyelid if needed. The examiner’s eye level must be aligned with the patient’s eye level, which may require the examiner to stand, bend, or sit.
Navigating the Examination Sequence
The examination begins approximately 15 inches (about one arm’s length) away from the patient’s eye. From this distance, the ophthalmoscope light is directed toward the pupil to locate the red reflex. This reddish-orange reflection confirms the light path is clear; any opacities appear as dark spots.
Once the red reflex is found, the examiner slowly moves closer to the patient, maintaining the 15-degree angle of approach. The goal is to get close enough that the ophthalmoscope is nearly touching the patient’s face. As the examiner moves in, the internal structures of the eye will become visible, though they may initially be out of focus.
The diopter wheel is then adjusted with the index finger to bring the retina into sharp focus, often starting with high plus lenses and rotating toward zero. The optic disc is typically the first structure sought, as it is the brightest and most distinct landmark. After focusing on the optic disc, the examiner systematically surveys the retina by pivoting the ophthalmoscope, following the retinal blood vessels. The macula, the area responsible for central vision, is examined last by asking the patient to briefly look directly into the light.