slitlamp

A slit lamp, also known as a slit-lamp biomicroscope, is a microscope designed for the examination of the eye. It combines a binocular microscope with a high-intensity illumination system that projects a thin, adjustable beam of light (a slit) onto the ocular structures, enabling cross-sectional and magnified views of the anterior segment.

The patient sits with the chin on a rest and the forehead against a stable frame. The operator can vary the slit width and height, adjust the illumination angle, and select magnification. Filters such as cobalt blue with fluorescein highlight corneal and lens defects, while a red-free filter enhances vasculature. Digital cameras or video may be attached for documentation.

Common applications include evaluation of the cornea, conjunctiva, iris, anterior chamber, and lens; assessment of corneal ulcers, scars, edema, and foreign bodies; measurement of anterior chamber depth and angle for glaucoma risk; and guidance of procedures or contact lens fitting. The apparatus can also be used with additional lenses to inspect the posterior segment.

Variants and accessories include standard tabletop slit lamps, portable handheld units for field use, and models integrated with imaging systems such as slit-lamp cameras or optical coherence tomography. Slit lamps are a core instrument in ophthalmology and optometry, supporting diagnosis, treatment planning, and documentation of eye conditions.