How to use an Opthalmoscope

Switch the room lights off or dim them, but don't make the room too dark. Prepare your patient IntroductionPrepare your equipmentRoom lightingPrepare your patientGet your own position...Dazzling examinationExplain what you are going to do to the patient. Warn the patient that the bright light can temporarily dazzle them. PositionPosition the patient so that he or she is comfortable but sitting up (if possible). To dilate or not to dilate?Pupil dilatation (with one drop tropicamide 1% in each eye and wait for 15 minutes) is useful to acquaint yourself with the normal fundus but may not always be possible, especially in neurology patients or those with a head injury.
Eye to eye
It is best to examine the patient's left eye with your own left eye and right eye with your own right eye—this takes practice. Try to keep your other eye open. Place your hand on the patient's forehead so that your fingers are splayed but your thumb is on the upper lid. This is important as you will use your thumb to hold the patient's lid open and also the joint of your flexed thumb is exactly where your forehead needs to end up. What am I looking for?Red reflexMedia opacities obscure the red reflex (corneal scars, cataract and vitreous haemorrhage, and asteroid hyalosis).Optic discLook for optic disc size, color (pallor, congestion), cup disc ratio, margins, haemorrhages, new vessels, collaterals. Pale and clearly demarcated disc: optic atrophy. Pathological cupping: glaucoma. New vessels on the disc: proliferative diabetic retinopathy is the most common cause. Yellow-grey disc with blurred margins ± haemorrhages: papilloedema—bilateral.VesselsStart at the disc and follow the vessels out to look for hypertensive and arteriosclerotic changes. Look as far as the mid-periphery for scars (inflammatory, laser), haemorrhages, exudates, pigment (white, black), and pigmented lesions. Examine arteries, veins (slightly thicker), and perivascular fundus. A-V nipping is seen in hypertension.Look also for: microaneurysms, blot haemorrhages, hard exudates—background diabetic retinopathy; cotton wool spots (fluffy white patches), vessel changes such as venous beading, and venous loops are preproliferative changes; leashes of new vessels.MaculaYou will find the macula temporal to the disc. The foveal reflex is seen better with a green (red-free) filter and is at two disc diameters away from the disc and 1.5 degrees below the horizontal (your whole field of view is 8 degrees). A circinate ring of hard exudates, haemorrhage (dot, blot, or flame), or pigment deposition are the most common things you will see.

Begin at arm's lengthBegin at arm's length by shining the ophthalmoscope light into the patient's pupil (you will then see the red reflex). Follow this reflex until your forehead rests on your thumb—you should immediately see the optic disc. It will probably be out of focus so, without moving your head, turn the lens dial either way—if the disc becomes clearer keep turning. If it becomes more blurred, turn the dial the other way. To look at the macula, ask the patient to look directly into the ophthalmoscope light. The ophthalmoscope can also be used for examining the anterior part of the eye by turning the lens dial to +10. What am I looking for?Follow a routine: red reflex, anterior segment, disc, vessels, and lastly macula . When examining the vascular arcades, ask the patient to look in the appropriate direction to extend your field of view.

COMMON MISTAKES
The biggest mistake doctors make when using the ophthalmoscope is not getting near enough to the patient. Don't be shy. Make sure you are very close to the patient, almost cheek to cheek, and that you maintain this throughout the examination. The closer you get, the wider your field of view. If you dilate the patient's pupils remember that he or she should not drive for at least one or two hours after dilatation, and longer if they feel their vision has not returned to normal. Even with dilatation, only about a third of the fundus is visible with a direct ophthalmoscope. Fortunately, the area most visible is the posterior pole (including the disc and the macula), where you should be able to see the ocular findings of many systemic diseases such as hypertension and diabetes Where the patient should lookIt is important to get your patient to fixate on a precise area (for example, the corner of the room or curtain rail). If you are too vague about this they will move their eyes. Instruct the patient to look at this spot no matter what—even if you get in the way. This spot should be located so that they are looking slightly away from you when they are examined—that is, to the left when you examine the right eye and vice versa.

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