The slit lamp is a diagnostic instrument consisting of a high-intensity light source (illumination system) that can be focused to shine a thin sheet, or slit, of light into the eye. It is used in conjunction with a biomicroscope (observation system) to examine both the front and back segments of the eye.

The slit lamp is used as part of an eye examination. The slit lamp can be used to view both the front and back segments of the eye including the eyelid, sclera, iris, lens, cornea and vitreous. The retina and corneal angle can also be examined using a handheld lens. This makes the slit lamp the corner stone of the ophthalmic assessment.

The eye care professional performing the examination will ask the patient to lean into the headrest, with the chin on the support and forehead against the bar. The operator will then move the slit lamp forward and focus a light onto the eye. This allows them to see the structures of the eye in high magnification.

A typical exam will take around 5-10 minutes as the examiner will use the slit lamp to view different parts of the eye using a variety of illumination techniques and may also perform tonometry pressure checks. The examiner may administer drops in the eye as part of the assessment; this can range from dilating drops (for back of the eye examinations) to fluorescein (staining drop) and anaesthetic. If drops are needed, the eye care professional will advise the patient on which drop they are using and any precautions they need to take.

When assessing the eye using fluorescein, a blue filter is required to excite the fluorescein. This is often used for corneal, tear film, and tonometry assessment. The blue filter has a wavelength of between 465 and 490 nanometres which will show the fluorescein clearly. The blue filter should not be confused with the green (red free) filter, which will not excite fluorescence. 

The yellow filter is used in combination with the blue filter. The yellow filter is a barrier filter, which sits in front of the optics. The blue filter will activate the fluorescein, showing any staining. When the yellow filter is engaged, it will block the blue wavelengths of light. This means only the activated fluorescein is visible, which can make subtle changes easier to visualize.

Want to learn more about filters? Why not check out our 'A practical guide to slit lamp filters' blog post https://uk.haag-streit.com/news-events/new/news/a-practical-guide-to-slit-lamp-filters.

The red-free filter (green filter) is used to increase contrast. It will block longer wavelengths of light at the red end of the spectrum. This makes red structures appear darker and increases contrast. This is useful when looking at vascular structure or when viewing small haemorrhages, especially on the fundus.

Want to learn more about filters? Why not check out our 'A practical guide to slit lamp filters' blog post https://uk.haag-streit.com/news-events/new/news/a-practical-guide-to-slit-lamp-filters.

There are four types of illumination: diffuse, direct, indirect, and retro illumination. Each of these has its own advantage when examining the eye.

Diffuse illumination is created by engaging a diffuser in front of the illumination mirror. This scatters the beam of light, creating a larger softer illumination. This is ideal for examining large areas of the eye when combined with a low magnification.

Direct illumination involves shinning the slit beam directly over the area of interest. The brightness, height, and width of the beam can be changed to show pathology. Techniques like optical section and parallelepiped illumination are performed using direct illumination.

Indirect illumination requires the slit lamp to be de-centred. This gives the illumination tower move movement, which allows the illumination to be placed adjacent to the area of interest. The light can be either scattered throughout the tissue, as is the case with a sclerotic scatter or reflected off different structures in the eye to backlight an area, as seen with a corneal retro illumination.

Retro illumination (red reflex) requires the slit lamp and optics to be aligned coaxially. Light is directed into the pupil and bounces off the retina. This can be used to visualize defects in the cornea or lens, or to transilluminate the iris. This is the same set up required to perform fundoscopy. 

For more information about types of illumination and illumination techniques, watch the Slit Lamp Examination video series or consider attending one of the Haag-Streit Academy slit lamp courses.

Changing magnification allows the clinician to focus on pathology in different structures of the eye. The amount of magnification required will differ depending on the clinic. For example, a corneal examination may require up to x40 magnification if the clinician needs to visualize the endothelial cells using a specular reflection technique. Whereas Goldmann Applanation Tonometry only requires x16 magnification. Imaging magnification is used when documenting a small section, to make the most of the full camera sensor. This requirement will affect the decision on which slit lamp to use. 

BQ 900, BP 900 and BX 900 all use a barrel magnification changer. The number at the top represents which magnification setting is currently engaged. BI 900 and BM 900 have a switch under the optics to change between two magnification options. 

Elara 900 uses a barrel magnification, which the clinician can change using the joystick. The magnification, slit height, width, brightness, and axis can all be pre-set and the operator can toggle through up to six pre-sets using the pre-set wheel, speeding up the examination by reducing the number of manual steps. 

Step 1: make sure the slit lamp optics are set correctly, as this ensures that operator and camera will focus on the same point (the human eye can accommodate, the camera cannot). To do this, rotate the optics until the focusing rod is sharp when seen through the optics. If the view is sharp though the optics but the captured image is blurry, the optics are not set correctly. If both the optics and captured image are blurry, then the slit lamp positioning is not correct.

Step 2: consider the type of image you wish to capture, whether that is an overview image or something more specific, like an optical section. The illumination will need to be balanced within the image. For assistance, why not download our full imaging guide. Different illumination techniques may be required to document a condition, if so, consider taking multiple images to create a photo essay. For example, a narrow slit can be used to document cataracts along with a retro illumination. 

If you would like to learn more about slit lamp imaging, consider attending one of the Haag-Streit Academy slit lamp courses. Alternatively, a bespoke training package can be created in which a Haag-Streit product manager will attend your place of work and run a training session. For information on the current event calendar, please visit Haag-Streit Academy or email the Haag-Streit Academy Team at hsacademy.uk@haag-streit.com.

Using a volk lens with the slit lamp enables the visualization of the fundus. This can take some practice as the slit lamp, lens, and eye need to be lined-up correctly.

To perform this examination, first, line the illumination coaxially with the optics. Next, position the slit lamp so that you are focused on the cornea with a red reflex visible. Then, introduce the volk lens between the eye and the slit lamp. Be aware that different lenses will have different working distances, for example a super widefield lens often needs to be held closer to the eye than a 90D or 78D.

Once the lens is in position, pull the slit lamp back towards yourself until the fundus view (as seen in the lens) is in focus. This can be difficult for beginners as there is a tendency to lower the arm holding the lens throughout the procedure; to help with this try resting the arm on an elbow rest, this has the added benefit of reducing muscle strain.

Want to learn more about examination techniques? Check out the slit lamp examination video series. 

Haag-Streit has a range of traditional slit lamps as well as the unique digital p-type slit lamp. The type of slit lamp you choose will depend on the clinical need:

Elara 900 -  uses a revolutionary projector type (p-type) illumination. This new form of illumination allows the user to create illumination pre-sets, which can increase workflow by reducing the number of manual steps required during a full examination. This slit lamp also has five magnifications (x6.3, x10, x16, x25 x40) as well as built-in video and imaging capture. It also boasts an ergonomic design with built-in inclined eye pieces.

BQ 900 - top of the traditional slit lamp range, with five magnification settings (x6.3, x10, x16, x25 x40) and a wide range of accessories available including IM 910 imaging module and inclined eye piece adaptor. These robust systems are perfect for those who require high magnification. 

BP 900 - designed for routine practice with three magnification settings (x10, x16, x25) and a wide range of accessories available, including the IM 600 imaging module. 

BI 900 - the successor to the much-loved BM 900. This slit lamp has two magnification settings (x10, x16) with the option of adding a BI 900 imaging set. 

BX 900 - the photographers slit lamp. Designed specifically for imaging, this slit lamp boasts five magnification settings (x6.3, x10, x16, x25 x40), an integrated DSLR or mirrorless camera, and bult-in xenon flash for unparalleled image quality.

All Haag-Streit slit lamps come with the highly-renowned Haag-Streit optics and the option to attach a Goldman applanation tonometer.

For further information about all of the Haag-Streit slit lamp models, please visit our slit lamps website pages. For more details, please contact our customer services team on 01279 883720 or email info.unitedkingdom@haag-streit.com.

We are happy to visit your site and perform a free slit lamp audit, which will provide you with a report detailing the condition of your slit lamps, along with any recommendations - whether that be to leave them be, service, upgrade, or replace. This can help you with long term procurement planning, especially if a large number of slit lamps are in need of attention. For further information, please contact our customer services team on 01279 883720 or email info.unitedkingdom@haag-streit.com.

Information on the range of Haag-Streit slit lamp tables can be found on the HS-UK website here. Models include the HSM 600 tables as well as the DOMS examination units. We also sell a range of Base Design tables. For further information, please contact our customer services team on 01279 883720 or email info.unitedkingdom@haag-streit.com.

All Haag-Streit slit lamps are available with wheelchair accessible tables. The Base Design twin lift table can be used for bariatric wheelchairs, without removing the foot rests.

Information on how to operate your Haag-Streit slit lamp can be found on the HS-UK website. Follow the links to your model from the Slit Lamp overview page. The ‘Instructions For Use’ can be found and downloaded from the bottom of the relevant slit lamp product page.

For hands-on guidance on how to operate your slit lamp, we recommend you attend one of our educational courses. Information on these can be found at Haag-Streit Academy.

Haag-Streit slit lamps can be on for as long as you need them. If you have a Tungsten bulb then this will eventually expire and will need replacing (for a replacement bulb, visit the HS-UK eshop).

The new BI 900 model has the same magnification steps as the BM 900 and additionally offers the opportunity to upgrade or include anterior segment imaging.

The cost of a Haag-Streit slit lamp will vary depending on which model you choose and which accessories you may need to accompany it.  For advice on which model may be most suitable for you and a full quotation, please contact our customer services team on 01279 883720 or email info.unitedkingdom@haag-streit.com.

If you are interested in purchasing a Haag-Streit slit lamp please contact us directly, either by speaking to your Area Sales Manager, or by contacting our customer services team on 01279 883720 or info.unitedkingdom@haag-streit.com. Please note, Haag-Streit is not on NHS supply chain. If you would like more information about purchasing options, please get in touch. We are happy to talk directly with procurement to assist with the process. 

Haag-Streit offers a range of imaging solutions for the traditional slit lamp. The BQ 900 has the option of adding an IM 910 or IM 600 camera. Both capture images and video, and the IM 910 has the advantage of a larger imaging sensor, aperture control, and optional 3D imaging. 

For the BP 900 there is the option to add an IM 600 camera and for the BI 900 there is the option of a BI imaging set. 

The Elara 900 has imaging built into the design and can capture images and video in either 2D or 3D (to activate 3D imaging in either an IM 910 or Elara 900 system, an additional licence is required). 

Haag-Streit's professional imaging slit lamp BX 900 is designed for capturing images of exceptional quality. The device utilizes a mirrorless DSLR camera (MILC) in combination with a powerful xenon flash. This gives the photographer full control over the illumination of the image, including aperture, shutter speed, and ISO control. To see the full potential of this device, check-out the fantastic entries from the Haag-Streit Slit Lamp Imaging Competition.

For traditional slit lamps, imaging models IM 910 and IM 600, and imaging set BI 900 are all capable of recording video. The new Elara 900 slit lamp has video and imaging capture built into the device and is 3D ready. 

The thinnest beam on a slit lamp is zero. It is a continuous width, but using a fixed aperture setting, it is 0.2mm.

You can add imaging to the BQ 900, BP 900 and BI 900 slit lamps. Haag-Streit offers the IM 910 and IM 600 imaging units for anterior examinations of the eye.

Haag-Streit Academy runs slit lamp courses to suit everyone, from beginners to more experienced users. Our slit lamp courses are presented by Mr Sunil Mamtora, Consultant Ophthalmologist at Bristol Eye Hospital. The slit lamp basic course covers the fundamentals including basic handling, tonometry, and fundoscopy. The advanced course covers techniques including gonioscopy and imaging. Both courses are a full day and run consecutively. You can attend either one or both days. The courses are suitable for anyone who wishes to improve their slit lamp skills. Six CPD points can be claimed for each day attended. 

We also offer bespoke training, delivered at your place of work and tailored to fit your specific needs. Click here for more information. 

The Haag-Streit Academy e-learning portal offers a free slit lamp e-learning course. To access the course, visit https://hs-uk.co/LearningPortal.

For information on the current event calendar and to view the agendas, please visit the Haag-Streit Academy web page or email the team at hsacademy.uk@haag-streit.com. We are happy to answer any questions.

The HS-UK Service Division is the only Haag-Streit authorised slit lamp service agent in the UK. We carry out an annual preventative maintenance visit for all our contract customers, as well as ad-hoc services for a one-off fee. A fully-qualified HS-UK Field Service Engineer will visit your premises and carry out an internal and external inspection, lubricate your slit lamps using Haag-Streit approved lubricants, perform a full optical alignment check and adjustment, and provide a detailed service report. Visit our HS-UK Service Division pages to find out more about taking out a service contract.

A variety of slit lamp accessories are available on the HS-UK eshop, including bulbs, dust covers and chin rest papers. If you cannot find what you are looking for on the website, please contact our customer services team on 01279 883720 or email info.unitedkingdom@haag-streit.com.

The bulb needed for your slit lamp will depend on the model. If you have a BQ 900, BP 900 or BM 900 you will need either an LED, Tungsten or Halogen bulb. The Tungsten bulb is available to purchase on the HS-UK eshop and is also suitable for older models of the BX 900. If you require an LED or Halogen bulb, please contact our Service Division on 01279 883720 or email service.uk@haag-streit.com. If you have a BI 900 then you will need an LED bulb. BD 900 and BC 900 slit lamps require Halogen bulbs which can be found on the HS-UK eshop.

It is possible to purchase a complete replacement for your head and chin rest. If you purely need to replace the plastic headband strap, this is also possible (part number 5702037). For either product, please contact the Service Division on 01279 883720 or email service.uk@haag-streit.com.

A cover is recommended for the slit lamp as it can help protect the slit lamp and prevent dust from getting into the system. We do sell slit lamp covers. Please contact your Area Sales Manager, or contact our customer service team on 01279 883720 or email info.unitedkingdom@haag-streit.com.