Digital Slit Lamp Camera Systems: How to Decide

Adding slit lamp photography to a practice can offer several advantages in addition to increased practice revenue. The fine detail can allow detection of slight changes of corneal findings, such as resolving corneal infections or edema. These recordings can also enhance patient care when a patient is being followed by multiple physicians for the same condition. By projecting the images to a larger screen, these photos can also serve as excellent teaching tools for patients to explain everything from meibomian gland disease to cataracts.

For today’s practicing ophthalmologist desiring to add digital photography to their slit lamp examinations, two options are available: custom built in cameras or beam-splitter adapters capable of attaching generic digital cameras. Many of the slit lamps, including some of the most popular models from Haag-Streit and Topcon, are capable of incorporating either one. Having an integrated camera offers several advantages to counter its greater cost: Typically these setups will take up less space, have less hanging wires, and be overall more visually aesthetic. Additionally, several incorporated camera slit lamps are designed to allow the operator to control image taking with buttons on the joystick, making photography much easier.

In selecting a camera system, you should become familiar with the types of cameras available. Digital cameras are available in CMOS (complimentary metal-oxide semiconductor) and CCD (charge-coupled device) image sensors. CMOS is generally less expensive to manufacture. CMOS sensors, however, are more susceptible to noise and have less light sensitivity. CCD cameras tend to have higher quality and more pixels. Digital color cameras generally use a Bayer mask over the CCD. Each square of four pixels has one filtered red, one blue, and two green (the human eye is more sensitive to green than either red or blue). The result of this is that luminance information is collected at every pixel, but the color resolution is lower than the luminance resolution. Better color separation can be reached by three-CCD devices (3CCD) and a dichroic beam splitter prism that splits the image into red, green and blue components. Each of the three CCDs is arranged to respond to a particular color. Therefore, to obtain the best digital video, a 3CCD device should be used.

For the more frugal ophthalmologist, a digital camera with a slit lamp adapter may represent a preferred option for upgrading already purchased slit lamps. While megapixels are important to keep in mind when selecting a camera (the higher number of megapixels can mean more detail), it is much less important than selecting a well fitting adaptor that is well suited to your camera. While most slit lamp companies offer their own form-fitted adaptors, similar often lower priced alternatives can be from third party companies such as Medical Workshop b.v. and TTI Medical.

Imaging software, whether for archiving or editing photos, is available from almost all developers of digital slit lamps. While very helpful in developing your images, it should be your lowest priority in selecting a system, as they are very similar and interchangeable should you prefer one system over another.

Whichever path you choose to incorporate digital slit lamp photography into your practice, you and your patients will certainly benefit. Several models are listed below to identify some unique characteristics available.

Carl Zeiss Meditec offers a DigiCam adapter for their SL 120 and SL 130 slit lamps. In addition, however, a continuously adjustable illumination system is available to brighten the field surrounding the slit.

Haag-Streit, in many of their models, incorporates a “history trigger” which not only captures one image but records the last few seconds in real time and lets you return to select the optimum image.

Oculus’ ImageCam 2 offers an excellent digital camera in one of the smallest systems available.