ophthalmoscopy

Ophthalmoscopy is the examination of the interior of the eye, including the retina, optic nerve, and retinal vessels, performed with an ophthalmoscope. It is used to detect diseases affecting the posterior segment such as diabetic retinopathy, hypertensive retinopathy, glaucoma, retinal detachment, age-related macular degeneration, optic neuropathies, and inflammatory or infectious conditions.

There are two main techniques. Direct ophthalmoscopy uses a handheld device with a bright light and lenses to view the fundus directly, producing an inverted or upright magnified image with a narrow field of view. Indirect ophthalmoscopy combines a headlamp or binocular viewing system with a condensing lens to project a larger, upright image of the retina, providing a wider field of view and better visualization of the periphery. The indirect method often requires dilated pupils and may involve scleral indentation to examine peripheral retina.

Procedure and preparation vary by method. For direct ophthalmoscopy, the clinician and patient are in a dim room; the examiner holds the ophthalmoscope close to their eye, aligns with the patient’s pupil, and looks through the instrument as the patient focuses on a distant point. For indirect ophthalmoscopy, the patient looks at a fixed target while the examiner holds the condensing lens at a set distance from the eye and views the retinal image through the viewing system. Pupil dilation with mydriatic drops is commonly used to improve visualization.

Findings focus on the optic disc (color, margins, cupping), retinal vessels (arteriolar narrowing, venous changes), and retina (haemorrhages, exudates, edema, detachments). Limitations include media opacities (cataract, vitreous hemorrhage), small pupils, and the learning curve required to interpret subtle signs.

Ophthalmoscopy has historical roots in the 19th century, with Hermann von Helmholtz credited for developing the modern instrument. It remains a core skill in ophthalmology and general medicine.