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How does an ophthalmoscope allow doctors to examine the inside of the eye?

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Two surgeons in scrubs and masks perform laparoscopic surgery on a patient in a brightly lit operating room, with medical equipment and a monitor displaying the procedure. — medicine Surgeons performing a laparoscopy.

An ophthalmoscope is a medical instrument designed to inspect the interior of the eye, specifically the fundus. It functions through a specialized system that combines illumination and observation.1

The device directs a strong beam of light into the patient's eye using a small mirror or prism. This light reflects off the retina and travels back through a small aperture in the instrument. By looking through this opening, the examiner can observe a nonstereoscopic, magnified image of the structures at the back of the eye.2

This process allows doctors to visualize critical components, including the optic disk, retinal blood vessels, the macula, and the choroid. Because it provides a clear view of these internal structures, the ophthalmoscope serves as an essential screening tool for diagnosing various ocular conditions, such as diabetic retinopathy.2