Indirect Ophthalmoscopy

• ​The image viewed through the oculars of the indirect is magnified and inverted (upside down and backwards), but it affords clear, stereoscopic views of large areas and the ability to directly examine the most peripheral structures.

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• Accordingly, it can be used to assess the posterior segment: structures in the eye posterior to the lens, including the vitreous, retina, choroid, and optic nerve. 

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Remember:​

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• The key is holding the condensing lens at the correct distance from the patient’s eye to get a magnified view of the pupil, while maintaining coaxial alignment between the light source and the image. Holding the lens inappropriately far or close to the eye will dramatically reduce the observable size of the retinal image and the ability to establish coaxial alignment. Lack of coaxial alignment will make it impossible to view the image.

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• The handheld condensing lens is most commonly a 20 or 28 diopter lens. 

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• Effective use of the indirect is markedly enhanced by pupillary dilation. 

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• Try to have the patient seated or somewhat reclined. 

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• Because the light source tends to be quite bright it is often helpful to apply gentle pressure to hold the patient’s eyelids open while examining. 

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• Asking the patient to look in different gaze directions will allow you to examine the entirety of the retina.