An ophthalmoscope is a medical instrument used by eye care professionals to examine the interior structures of the eye, particularly the retina, optic nerve, and blood vessels. It consists of a light source and a series of lenses that allow the examiner to see through the pupil and into the eye. This examination helps in diagnosing various eye conditions and diseases. The device can be handheld or mounted, and it often features adjustable lenses to accommodate different vision needs. By using an ophthalmoscope, doctors can detect issues such as glaucoma, diabetic retinopathy, and other ocular diseases early, which is crucial for effective treatment.