Buyers’ Guide to Slit Lamps

Wendy W. Lee, M.D., M.S.

About Author

All ophthalmologists know the importance of a good slit lamp. The choices are endless but making the right one is essential. Below are some highlights of several slit lamps to aid in the decision if you are setting up a practice. The slit lamps are categorized by manufacturer.

Carl Zeiss Meditec, Inc.
Zeiss is a leader in ophthalmic technology. Their slit lamps are familiar to many of us who have used them in training.

• SL 115 Biomicroscopic Slit Lamp 
  This is their classic, affordable slit lamp that is good for all routine slit lamp exams and is superb for contact lens fittings because of the standard swivel-type yellow filter. The SL 115 has a fine, precise slit and a large illuminated visual field. The high eyepoint eyepieces ensure greater comfort, even for those who wear spectacles. All controls are located for one-hand adjustments of both slit and operating functions. The SL 115 provides reliable protection against UV and IR light in compliance with ISO 10939. This slit lamp may be configured with a compact video adapter for documentation using a video recorder or miniature camera. This system is completely assembled and ready to go. After removing it from the packaging, it can be placed directly on an instrument table or examination unit and secured with 2 screws or adhesive pads. An integrated self-sensing power supply is included.
• SL 120 Biomicroscopic Slit Lamp 
  The SL 120 is versatile. The optical system generates a crisp image with sharp definition for slit rotation, slit decentration for retro-illumination and an illuminated field of 14mm. An optional tiltable prism head is available. The SL 120 has a high transmission capability to minimize light loss allowing more light for observation and greater protection of the patient’s eye from excessive irradiation. This slit lamp is designed with a short working distance and a single-handed controls for sensitive adjustments of the slit length, width and rotation. There is a quick-action lock to ensure firm fixation in any position at any time. Accessories include devices for digital documentation, applanation tonometers, laser attachments and more. Camera accessories include 1CCD and 3CCD cameras. The 3CCD cameras may also be attached utilizing a beam splitter and appropriate optics. The system is compact and lightweight. The DigiCam adapter allows attachment of various digital cameras for both survey and slit photos. An additional continuously adjustable illumination system is available to brighten the field surrounding the slit. VISUPAC, a specially developed ophthalmology software containing a professional database and image processing functions can also be used as a supplement.
• SL 130 Biomicroscopic Slit Lamp 
  This slit lamp has a dual application design and can be used as a traditional slit lamp and/or for laser therapy. The controls of this slit lamp are symmetrically arranged and can be operated with either hand when the projector is in its central position. The configuration also allows the use of different prism heads and a micromanipulator. Like the SL 120, the optical system generates a crisp image with sharp definition for slit rotation, slit decentration for retro-illumination and an illuminated field of 14mm. The prism head can be tilted by up to 20%. The SL 130 also has high transmission capability like the SL 120. Accessory options are the same as those for the SL 120.

Haag-Streit USA, Inc
Haag-Streit is another leader in ophthalmic technology, especially when it comes to slit lamps. They have designed slit lamps for the emergency room setting, clinic, and professional photographers, as well as a hand held slit lamp.

• BQ 900 LED Slit Lamp 
  This slit lamp has 2 ports and offers simultaneous video and still photography through either professional or consumer level cameras integrating the IM 900 Imaging Module. Optional accessories include a teaching scope, inclined eyepiece (up to 20 degrees) to reduce neck strain and a unique stereo variator for the retina specialist. The stereo variator reduces the 13-degree angle to 4.5 degrees, enlarging the binocular field of view even with myopia or through small pupils. The knob on the power supply controls the continuous illumination of the field. A Goldmann tonometer may be added to the system. A beam splitter can be used. Magnification can be changed from 6 up to 40x.

Keeler Instruments Inc.
The slit lamps from Keeler are available through the USA site.

• Keeler Classic Portable Slit Lamp 
  Roughly $4000, this portable slit lamp is lightweight, durable and robust. This slit lamp features fixation targets and 1mm square light patch for assessing anterior chamber flare. There are 10x and 16x magnifications, controllable illumination from maximum to zero and an aluminum chassis. An iPhone 4 imaging adapter can also be used with this device.
• SL-40 H Haag Type Slit Lamp 
  This slit lamp has the same features as the SL 33 Zoom slit lamp. The differences are the drum change magnifications of 6x, 10x, 16x, 25x, and 40x. The converging optics are also 8.5 degrees. The price is approximately $6700.
• SL-40 Zeiss Type Slit Lamp
  This system is similar to the SL-40 H slit lamp, but it is more compact. The price is a bit lower at approximately $5500.
• SL-40 Di Digital Still/Video Slit Lamp
  Building on the optical system of the SL 40 H slit lamp, the illumination system is upgraded, an external fiber optic illumination system with diffuser is added and the optics are optimized for a digital camera and video imaging. Software can be added for patient database and image processing. The price is approximately $15,000.

Kowa Optimed, Inc.

• Portable Slit Lamp SL-15
  This hand held slit lamp is cordless, rechargeable and weighs less than 800g. It operates with a halogen light source. There are 3 adjustable slit sizes, a cobalt blue filter, and a built in spot illumination. It offers 10x and 16x magnification. The stand doubles as a charger that simultaneously charges both the slit lamp and an optional spare lithium ion battery. Options include a C-mount adaptor allowing digital and video cameras to be attached and a headrest.

Lumenis Vision
Lumenis is well known for their laser systems and they also make the following slit lamps.

• Insight Retina Slit Lamp
  InSight is a fully integrated, advanced laser delivery technology and slit lamp bio-microscope. This system uses Lumenis’ patented collinear (CoLin) design, which projects both illumination and laser beam on the same pathway. The CoLin mechanism is controlled directly through the InSight’s integrated joystick, which features their patented AcuGuide technology for fine movement and beam manipulation. The unit’s stereoscopic angle was designed to provide better depth perception and superior peripheral viewing. This system features a homogeneous laser spot at the target tissue with evenly distributed power across the full diameter of the spot. ClearView filters’ photopic balanced coating eliminates color distortion of the treatment site while optimizing white light transmission.
• Lumenis 1000 Slit Lamp
  This slit lamp is a fully integrated bio-microscope slit lamp laser delivery system. It comes with built-in LaserLink, parallel optics, magnification changer, micromanipulator and automatic eye safety filters (532 nm, 561 nm, and 659 nm) and wheelchair accessible power table. This lamp is compatible with the Selecta Trio, Novus Spectra, and Novus Varia. It has 50 – 1000 um Z-Link containing SureSpot optics. It also has ClearView filters for enhanced visibility, a switchable physician elbow rest and an auto-sensing 100 – 240 V input power.
• Lumenis 990 Slit Lamp
  This is a diagnostic slit lamp bio-microscope that is compatible with Selecta II and Novus Spectra Laser Systems. It has convergent optics, a tonometer mount, locking caster wheels and a power table that is wheelchair accessible. It easily adapts to Convergent Optics LaserLink and has an auto-sensing 100 – 240 V input power.

Marco

• Ultra G5 Zoom Slit Lamp
  Marco has redesigned the Ultra series utilizing a multi-layered, multi-coated system, which transmits light more efficiently, producing a 20% increase in optical resolution and clarity. The redesign also results in a 20% increase in light transmission, a 15% expanded field of view and a 14% increase in depth of field. The Galilean optics feature a 6-degree convergence angle for the binoculars. The high-eyepoint eyepieces create a field of view 1.3x wider than conventional slit lamps. The eyepieces are threaded and locking to eliminate slipping. They also feature individual adjustable dioptric rings for neutralizing refractive error. Magnification ranges from 5.9x to 35x. The G5 model has a ‘flip-up’ magnification display mirror. This slit lamp also has a high-resolution motorized zoom optical system, adjustable by the fingertips to switch zoom/focus and illumination intensity. There is a specially coated reflection mirror that reflects harmful UV rays. There is an LED fixation light and an optional large patient headrest. Accessories include applanation tonometers, Hruby lenses, assistant scopes, beam splitters for full video equipment, and inclined oculars to reduce neck strain.

Nidek, Inc.

• Slit Lamp SL-1800
  This slit lamp has a Galilean converging binocular microscope and a wide field high eye point type eyepiece. It also has a yellow filter for easy observation and evaluation of contact lens fit in fluorescent light. The single joystick allows for smooth 3D movements.

OCULUS, Inc.

• OCULUS ImageCam 2 Digital Slit Lamp Camera
  This is one of the smallest digital slit lamp camera systems. An image or video is taken by the high resolution, digital video camera in the beam path of the slit lamp. Exposure time, light magnification and white balance can be easily adjusted with its software. This allows pictures to be taken in different segments of the eye. There is a beam splitter, the prism can be moved in and out of the beam path and the aperture can be adjusted for greater depth of field.

Reichert Technologies

• PSL Portable Slit Lamp
  This portable slit lamp uses a high luminance white LED light source, providing about 10,000 lux of white light and has a lifespan of 50,000 hours or more. This slit lamp comes with 2 long-lasting batteries that can power the unit at a maximum illumination for up to 2 hours. It also comes with its own charger. It weighs only about 1.5 lbs. with its battery. It comes with 10x and 16x eyepieces, a diopter adjustment of 7D and working distance of 3.15 inches. It has cobalt blue, red free, and color temperature conversion filters.
• XCEL 255 Slit Lamp 
  This unit’s wide-field optics provide clarity and detail through a Galilean microscope. It comes with 10x, 16x and 25x magnifications with a slit rotation of 0 – 180 degrees. There are red free, cobalt blue and heat absorbing filters. Illumination uses a 6V 20W halogen light. Table base dimensions are 465 x 316 mm and it weighs about 52 lbs.
• XCEL 400 Slit Lamp
  Like the 255 slit lamp, the 400 operates with a Galilean microscope with 10x, 16x, and 25x magnification. Slit rotation is the same. It includes a neutral density filter in addition to the others on the 255 model. Illumination is the same, as well as the dimensions.
• XCEL 700 Slit Lamp
  The 700 slit lamp differs from the 400 by the magnification: 6x, 10x, 16x, 25x, and 40x. Other than that, they are very similar.

Topcon Medical Systems

• SL-1E Slit Lamp
  This slit lamp has a 14mm width and height slit illumination with cobalt blue and red free filters. It has 10x and 16x magnifications with the 10x eyepieces and 16x and 25x magnifications available with the 16x eyepieces. It uses halogen illumination.
• SL 2G Slit Lamp
  This slit lamp uses LED light instead of traditional bulbs. It has 10x, 16x, and 25x magnification. The oculars are Galileo convergence type and accept the attachment of a beam splitter. R-900 and 870 type applanation tonometers can be mounted. This unit also has red free and cobalt blue filters.
• SL 3G Slit Lamp 
  This slit lamp is a stereoscopic converging microscope using a halogen bulb. It has 4 built-in filters: cobalt blue, red free, 13% neutral density and heat absorbing. It has an angular measurement scale for the fitting of astigmatic contact lenses. Magnification can be changed from 1x to 1.6x.
• SL-D2 Digital-Ready Slit Lamp
  The SL-D2 is part of Topcon’s D-Series Digital Slit Lamps. It can be used as a conventional examination instrument or with the optional DC-3 integrated digital camera for 8 megapixel imaging. There are magnification ratios of 10x, 16x, and 25.6x selectable with a Galilean-type drum.
• SL-D4 Digital-Ready Slit Lamp
  The SL-D4 differs from the SL-D2 in that it has 5 magnification ratios of 6x, 10x, 16x, 25x and 40x. The 40x magnification is useful in corneal endothelium observation. It also has the option for an 8 megapixel imaging camera.
• SL-D7 Digital-Ready Slit Lamp
  The SL-D7 with its optional Digital Photo Attachment is the only digital photo slit lamp with a flash-through-the-slit illumination system, allowing for precision in slit lamp photography. This slit lamp can be interfaced with the optional DC-3 digital camera or the Nikon photo attachment for 12 megapixels of resolution. It has the same 5 magnification ratios as the SL-D4. It has convergent binocular tubes and an incorporated amber filter.
• SL-D8Z Digital-Ready Zoom Slit Lamp 
  The SL-D8Z is Topcon’s ultimate diagnostic slit lamp, with a 5:1 zoom ratio and a 6.4x to 32.1x magnification range. It can be outfitted with the Topcon DC-3 or the Nikon 12 MP digital photo attachment.

The various slit lamps listed above are not the only ones, but are some of the main players in the game. When it comes time to choosing your slit lamp, test drive them at one of the meetings and see what you are most comfortable with and explore which unit best fits your needs, whether it be basic diagnostics or slit lamp photography, for instance.