Slit Lamp Buying Guide: What to Compare

Optics and magnification

Most modern slit lamps use a Galilean magnification changer with three or five steps. Five steps give finer control between a wide overview and high magnification for detailed examination. Look through the instrument at every step: the image should be sharp, bright and free of haze, and both eyepieces should merge easily into one image.

Illumination and filters

LED illumination runs cooler, lasts longer and keeps a stable colour. Halogen illumination is found on older and some current models and needs spare bulbs. Check the slit width and height controls move smoothly, and that the standard filters are present: cobalt blue for fluorescein, red-free, and a yellow barrier filter if you use one.

Imaging

If you document findings or teach, consider a slit lamp with an integrated camera, or one with a beam splitter that accepts a camera. Confirm the imaging software runs on your computers and can export to your records system.

Tonometer and accessories

Check whether the slit lamp accepts the applanation tonometer you use, how it mounts, and whether breath shields, a fixation target and chin rest paper are included.

Ergonomics and table

A clinician uses the slit lamp for hours each day. Check the joystick moves smoothly and precisely, the eyepieces adjust for your posture, and the table height suits both seated and wheelchair patients. A motorised instrument table often matters as much as the slit lamp itself.

What to check on a pre-owned unit

Slit lamps are durable and a good refurbished buy. Confirm the following:

• Clean, undamaged optics with no haze or fungus.
• Smooth joystick, slit and magnification controls.
• Working illumination, with spare bulbs if it is halogen.
• Filters, chin rest, forehead rest and breath shield present.
• Table, tonometer and camera included, if listed.