Binocular indirect ophthalmoscopy
Like its direct counterpart described above, binocular indirect ophthalmoscopy is used to inspect the retina. However, with this technique a large area of the retina can be viewed instead of a only a small portion as seen with direct ophthalmoscopy.
The device consists of a headband, an optical viewing system, and a controllable illumination source. The lens system has eyepieces that are adjusted depending on the practitioner’s distance from the patient. In addition, a condensing lens held in the doctor's hand near the patient’s eye is used to generate an image of the retina.
With binocular indirect ophthalmoscopy the eyecare practitioner has the advantages of a large field of view, bright illumination, a comfortable working distance from the patient, and little periphery view distortion. The pupils are dilated prior to performing this test.