iBEX LED Slit Lamps

With modern optical design typical of high end surgical microscopes,
iBEX LED Slit Lamps deliver high definition observation with reduced reflections and the widest field of view.
Ultimately, the user achieves improved diagnosis and less observation strain.

LED Illumination

The proprietary LED for iBEX Slit Lamps deliver the industry’s brightest and most uniform
illumination. Wavelengths are full spectrum and synced to maximize anterior and posterior observation.
Most importantly, heat to the patient’s eye has been reduced by nearly 80% less compared to traditional illumination, resulting in greater patient comfort during intense and prolonged observation.

EZ Shipping and Setup

We’ve made the process simple. Ibex slit lamps are 95% pre-assembled and shipped direct to your office by FedEx.Unpacking and installation takes 20 minutes or less.




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Slit Lamp Examination

The slit lamp is essentially a simple and generally under-used piece of equipment. It consists of an illumination system and a binocular observation system, which when correctly aligned will result in a coincidental focus of the slit and microscope.
Illumination system
Basically a short focus projector projecting an image of the illuminated slit aperture on to the eye. This part of the system should be flexible to allow various sizes and shape of slit beam. Usually a rheostat is incorporated and the lamp house can be rotated. Neutral density, cobalt blue and red free filters are usually available, and occasionally a diffuser and polariser.
Observation system
Consists of a binocular microscope with parallel or convergent eyepieces (some practitioners may get diplopia with parallel eyepieces). Generally magnification from 6x to 40x is allowed by varying the eyepiece and objective lens of the microscope.
Note
The illuminating system and observation system are normally focused at the same point - coupled. Although there are some occasions when it is better to focus the slit at a different point to where the observation system is set-de-coupled.
Before commencing any work with the slit lamp it is important to ensure that your instrument is correctly set up:

1. The eyepieces should be focused for the observer (this can be facilitated if the observer knows their refractive error and uses the dioptric scale found on most slit lamps). Often a little more minus is required than the observer's refractive error due to proximal accommodation and convergence (it is always wise to 'think far' when viewing through this type of instrument). Before examining a patient it is essential that the eyepieces are correctly set for your own refractive state. Because the eyepieces are mounted convergently, this setting will be at a more myopic point than expected. Since no cross lines are provided within the microscope, the focussing rod, which is in the drawer of the slit lamp table must be used. This rod, which has a flat end, should be mounted in front of the microscope by removing the flat grooved alloy plate which is engraved 'Clement Clarke' and by inserting the rod in its place. The slit beam should be directed to the centre of the flat face of the rod and set at about 1-2 mm in width. The eyepieces should be set individually by focussing on the slit image moving the eyepiece from the positive side of the scale and stopping at the point at which the image first appears sharply focussed, thus avoiding stimulating accommodation. You should then note the setting on the eyepiece scale and always use this setting when using the slit lamp. There is no need to use the focussing rod after this occasion. If the focussing rod is missing the slit beam should be positioned on the closed upper lid of the subject and then illumination system swung from side to side checking for parallax movement. Adjust the position of the illumination system until there is no parallax movement and then focus the eyepieces in turn. (ask for a demonstration).
2. The pupillary distance (pd) is adjusted for the observer (again perhaps the pd should be slightly less than that usually measured to account for proximal convergence).
3. Check that the slit lamp is parallel on the runners of the table.
4. Check that the observation and illumination systems are coupled, and that the slit beam is of even illumination and has sharply demarcated edges (otherwise irregularity of the beam may be falsely interpreted as irregularity of tissues).
5. The locations of the controls are known.
6. The observer and patient are comfortable in the mid-travel of the slit lamp. Mid-travel is the location of the slit lamp when it is half-way up or down its possible vertical range.

Using the slit lamp
When using the slit lamp it is important that you are aware of the various techniques you are employing and when to use them. As with any technique, a general routine should be established, in most cases when examining the eye and adnexa a general rule of thumb might be-use a large field of view initially and then focus in on detail when required with larger amounts of magnification.

Commence the examination using the 10x eyepieces and the lower powered objective i.e. 1x. Use the lowest voltage setting on the transformer. Select the longest slit length by means of the appropriate lever (17). Adjust the chin rest by means of control 27 so that the patient's eyes are approximately level with the black marker on the side of the head rest. Adjust the height of the slit lamp until the slit beam is centred vertically on the patient's eye. Focus the slit beam on the eye by moving the joystick (1) either towards or away from the patient. Coarse positioning can be effected without using the microscope but critical focussing should be carried out whilst viewing through the microscope.

The slit width is varied by rotating either the left hand or right hand knurled control 10. To vary the angle between illumination and microscope use one or other of these same controls as handles.

The slit should be set primarily in the vertical position, but any desired inclination can be achieved by means of the ball handle 15 (notches at 45°, 90°, 135°; stops at 0° and 180°). By tripping the latch 11 and tilting the slit lamp column, the beam can be introduced from as much as 20° below the horizontal. This is mainly used for carrying out gonioscopy.

For observation by sclerotic scatter or other dissociated forms of examination the centring screw 13 is loosened, so that the slit image can be moved away from the centre of the field of observation. The image is centred again by tightening the screw.

Carry out the techniques described below.

Description 

1) Control lever for horizontal coarse and fine adjustment.

2) Fixing screw for the horizontal movements.

3) Gliding plate

4) Accessory drawer

5) Pilot light

6) Fuse

7) Rotary switch

8) Rail covers

9) Headrest

10) Fixing screw for the microscope arm.

11) 2 knobs for coupling the microscope arm to the lamp arm (invisible).

12) Roller for setting the angle between microscope and illumination.

13) Index for reading angles.

14) Scale for reading the angle between microscope and illumination unit.

15) Guide plate for pre-set lenses and applanation tonometer.

16) Level adjustment control for the chin rest.

17) Chin rest.

18) Fixing screw for the microscope.

19) Lever for changing the objectives.

20) Interchangeable eyepieces.

21) Knurled rings for setting the eyepieces.

22) Interchangeable illumination mirror.

23) Knurled knob for lateral adjustment of the fixation light.

24) Clamping nuts for the lamp housing.

25) Cover for lamp housing.

26) Scale for slit diaphragms.

27) Lever for three filters.

28) Control for rotation of slit, for varying the slit length and interposing the blue filter.

29) Lever marker.

30) Fixation lamp.

31) Handle for focusing the fixation target.

32) Slide for pre set lens.

33) Centring screw.

35) 5° stop.

34) Latch for the angle of inclination.

35)Controls (2) for setting the slit width.
Methods of observation
The slit lamp offers a variety of illuminating and observing methods which do not all have to be used in routine examination, but the ability to perform them should be practised. Not all slit lamps will allow all methods to be performed.
The following is a suggestion as to the way a routine technique should be performed-it is by no means the only way to perform a slit lamp routine and indeed not all practitioners will do so. A good routine is one that you feel comfortable with and that allows you to detect and investigate any irregularities and note the normal condition (base-line data) of the eye.

The examiner uses one hand to operate the joystick and the other to control the magnification, fixation light position and the type and angle of illumination, merging from one method to another until the examination is complete. The setting-up and use of each kind of illumination must be practised until the proceedings become automatic. NOTE: regardless of the type of illumination used, to examine the entire cornea/sclera/lens you must ask the patient to look up, down, right, left (holding the upper or lower lid when necessary). 

Types of illumination are:

1) Diffuse illumination

2) Direct (focal) illumination

(a) narrow beam (optic section)

(b) broad beam (parallelepiped)

(c) conical beam

3) Indirect illumination

4) Retro illumination

(a) direct

(b) indirect

5) Specular reflection

6) Sclerotic scatter

7) Oscillatory illumination

8) Tangential illumination

Diffuse illumination
This is a good method of observing the eye and adnexa in general. Diffusers are sometimes supplied with slit lamp and can be 'flipped-over' the illuminating system. Diffusers are generally ground glass plates that cover the light source, if these are not available a piece of tissue might suffice to diffuse the light although this can sometimes be precarious as the tissue often falls off! The slit should be opened wide and the magnification should be set as low as possible to enable a large field of view. 

Direct/focal illumination
This is the most common method of viewing all tissues of the anterior eye, the focused slit is viewed directly by the observer through the microscope. The magnification can be increased quite markedly (10x to 40x or more) to view any areas of interest in greater detail.
Any size or shape of beam can be used, and it is important to be aware of the main options.

(a) Broad beam (parallelepiped)
Generally a very wide beam is used for surface study, whilst a very narrow one is used for sections. A useful combination of the two is the parallelepiped section of the cornea, which uses a 2mm slit width enabling corneal surface as well as stroma to be studied. This allows us to ascertain the depth of any interesting feature e.g. foreign body, corneal abrasion. Direct illumination on the front surface of the crystalline lens reveals the 'orange peel' effect (produced by the cell bodies of the lens fibres just below the front surface of the lens), and on the iris allows observation of iris pattern.

(b) Narrow beam (optic section)
This technique is only used if you wish to investigate something. It should not be used to search for abnormalities. However, once an abnormality has been found it is easier to determine the precise depth using an optical section. The resolution of the section can be improved by reducing the slit width to a minimum, and be viewed more clearly by increasing the magnification. Generally the angle between the illuminating and observation systems should be set around 45 to 60 degrees, however to increase the amount of cross section, this angle can be further increased to 90 degrees. A good corneal section will allow at least 4 layers to be seen - tears (outer), epithelium (and Bowman’s membrane), stroma seen as the central grey granular area and the fainter back line which is the endothelium (and Descemet’s membrane).
When looking at the lens, variations in refractive index and transparency can be seen allowing observation of the Y sutures and any lens opacities. Opacities scatter and reflect more light and therefore appear white against the grey background. Sometimes due to pigmentation, opacities may appear blue (congenital) or brown.


van Herick’s Technique
A further use of an optical section is to assess the degree of openness of the anterior chamber angle. The method is as follows:

Use a low magnification (6x or 10x) to give an adequate field of view. Set the beam 60 degrees to the side of the microscope and place a narrow slit as close to the limbus as possible and normal to the cornea. To assess anterior chamber depth you compare the width of the cornea seen by the optical section with the dark section seen between the front surface of the iris and the back of the cornea. The findings are classified into four grades:
 
GRADE 4: The ratio of aqueous to cornea is 1:1 - open angle
GRADE 3: The ratio of aqueous to cornea is 1:2 - open angle
GRADE 2: The ratio of aqueous to cornea is 1:4 - indicates narrow angle, which should be viewed by gonioscopy.
GRADE 1: The ratio is smaller than 1:4 - indicates dangerously narrow angle, which is likely to close.
(c) conical beam
An important modification of direct illumination is used when inflammatory cells within the anterior chamber are suspected (as in acute anterior uveitis). This will show up as aqueous flare, and can only be accurately seen using a conical beam of light, set at an angle of between 45 and 60 degrees and focused onto the front surface of the cornea. Using the pupil as a dark background, aqueous flare may be seen in the space between the focused beam of light on the cornea and the out of focus beam on the lens. In the normal eye this space will be perfectly clear. To use this technique the room illumination must be completely dark.

Indirect illumination
This simply means looking at tissue outside the area which is directly illuminated and can be used in conjunction with most of the above techniques. Structures are often easier to see under indirect illumination as glare is reduced e.g. opacities, corneal nerves and limbal vessels. When using the slit lamp direct and indirect illumination are viewed simultaneously, structures viewed in the illuminated field are seen under direct illumination, but as this does not fill the whole of the field of view, anything which reflects or scatters light from outside the illuminated area is being viewed by indirect. It is therefore important to look at the entire field of view and not just the illuminated patch.
If you wish to view a certain feature by indirect illumination first locate it by direct illumination and keeping your viewing system unchanged swing the lamp to one side. Occasionally it is necessary to de-couple the beam to enable you to move the beam to one side.

Retro-illumination

This is another form of indirect viewing. The light is reflected off the deeper structures, such as the iris or retina, while the microscope is focused to study the more anterior structures in the reflected light. The most typical use is to study the cornea in light reflected from the iris, or the lens in light reflected from the retina. Features that are opaque to light appear dark against a light background (e.g. scars, pigment, and vessels containing blood). Features that scatter light appear lighter than the background (e.g. oedema of the epithelium, corneal precipitates). Note that this method is useful for examining the size and density of opacities, but not their location.

1) Use a parallelepiped focused (for example) on the iris.

2) For direct retro-illumination: the observed feature on the cornea is viewed in the direct pathway of reflected light. The angle between the microscope and the illuminating arm is about 60°.

3) For indirect retro-illumination: the angle between the microscope and slit-lamp arms is greatly reduced or increased so that the feature on the cornea is viewed against a dark background. It may be necessary to uncouple the beam. 

Specular Reflection

This type of viewing is achieved by positioning the beam of light and microscope such that the angle of incidence is equal to the angle of refection. The light can be reflected from either the anterior (i.e. tears & epithelium) or posterior (i.e. endothelium) corneal surface. Note that the reflected light should pass through only one eyepiece, and therefore this method is monocular.

Method for viewing the anterior surface

1) The angle between the light and microscope arms should be about 45°

2) Use a magnification of about 25 times, and a moderate parallelepiped.

3) Gradually change the angle of the light source until a bright area of pre-corneal fluid is seen. Elevations and depressions of the anterior surface appear as dark spots in the brightly reflected area. Details of the pre-corneal film, mucous secretion, and corpuscular elements of tears may be seen.

Method for viewing the posterior surface

1) The angle between the light and microscope arms should be about 60°

2) A 2mm wide parallelepiped and magnification of 20-25x is used.

3) Find the image of the illuminating bulb, then move the light beam until the image of the bulb is just behind the posterior surface of the parallelepiped. Incidence = reflection when the dazzle from the pre-corneal fluid is seen.

4) Focus on the back of the parallelepiped. A mosaic of hexagonal endothelial cells will appear. The posterior endothelium and keratic precipitates may thus be studied.

Uses

1) To examine the epithelium and endothelium. Note that the quality of the reflection formed gives an indication of the quality of the surface from which the light is reflected.

2) Examination of the tear film.

3) Examination the crystalline lens.

Note
This technique is basically a method of evaluating the reflective qualities of the surfaces of the eye, and gives an indication of the surface quality. The four Purkinje image's are used as backgrounds - the first to view the tears / epithelium, the second to view the endothelium of the cornea, the third the anterior surface of the lens capsule and the fourth, the posterior surface of the lens capsule.
This method of illumination is particularly useful to examine the endothelium layer of the cornea (e.g. blebs, polymegathism), although very high magnification is necessary, at least 40x is required and to see individual cells 80x. As deeper layers are viewed with this method the angle between the two systems needs to be reduced (only 5 degrees between them is required when viewing the posterior lens capsule).

Sclerotic scatter
This method uses the principle of total internal reflection. A narrow vertical slit (1-1.5mm in width) is directed in line with the temporal (or nasal) limbus. A halo of light will be observed around the limbus as light is internally reflected within the cornea, but scattered by the sclera. Any corneal opacities, oedema or foreign bodies will be made visible by the scattering light, appearing as bright patches against the dark background of the iris and pupil. It is important that the room illumination is as dark as possible.
For this technique, the cornea is usually viewed by the observer's naked eye, from around the side of the microscope, however it is possible to observe the cornea using the microscope as well. To do this the slit must first be focused with direct/focal illumination (see below) on to the debris of the tear film. This ensures that the corneal surface is focused correctly. Then without moving the observation system or the entire slit lamp, the system is de-coupled and the illuminating system directed at the limbus. This will give sclerotic scatter and still allow the anterior surface to be viewed through the microscope, and allow the observer to use the most appropriate amount of magnification.

Oscillatory Illumination

A beam of light is rocked back and forth by moving the illuminating arm or rotating the prism or mirror. Occasional aqueous floaters are easier to observe. Can also be used to determine the extent of opacities in the crystalline lens.

Tangential Illumination

The iris is examined under very oblique illumination while the microscope is aligned directly in front of the eye. Useful for examining tumours and naevi of the iris.

Indications for slit lamp routine examination in private practice
It certainly can be argued that slit lamp examination is the very best method of examining the external eye and should therefore be used with every patient. Here is a list of ocular conditions and complaints that could warrant slit lamp examination:
1) Conjunctival injection
2) Lacrimation
3) Itchiness
4) Grittyness
5) Pain
6) Dry eyes
7) Photophobia
8) Haloes around lights
9) Narrow anterior angle
10) Recent foreign body sensation
11) All contact lens wearers
12) History of anterior uveitis
13) Ingrowing eyelashes
14) Pterygia
15) Blepharitis
16) Meibomium cysts
17) Styes (hordeolum)
18) Unexplained reduced visual acuity
19) Lens opacities (best seen through dilated pupil)
20) Iris pigmentation
21) Irregular pupil margins
22) Increased IOP over 40mm Hg (possible corneal oedema)
Attachments for the slit lamp
Goldmann tonometer - IOP measurement (applanation tonometry)
Pachometer - measures corneal thickness. Readings of 0.60mm and above suggest oedema may be present.
Gonioscope - used to assess anterior angle.
Binocular Indirect Ophthalmoscopy - (Volk lens or Hruby)
Used to view fundus.
Camera attachments - can be used to photograph and record the external eye of a patient
Aesthiometry - to measure corneal sensitivity.

10 Steps to a Better Slit Lamp Examination

10 Steps to a Better Slit Lamp Examination
Brush up on this essential part of every eye examination.
By Etty Bitton, OD, MSc, FAAO

Are you getting the most out of your slit lamp exam (SLE)? Like most, your slit lamp skills have no doubt improved with time. To maximize the use of your slit lamp, try adding the following 10 reminders to your routine.

1. Clean Up Your View

Whether or not you cover your slit lamp at the end of the day, dust and oils from your eyelashes will soil the oculars. Make sure you dust the mirror of the illumination column as well as the patient side of the oculars. You can use a small brush, which usually comes as part of the slit lamp accessories, to dust off the mirror. Adding a routine cleaning will keep your image sharp. 



 2. Adjust Your Oculars

This step may be more pertinent if you practice in a group or hospital
 setting whereby several individuals share the equipment. Verifying the
 interpupillary distance of the oculars prior to evaluation will maximize
 three dimensional (3D) viewing of the ocular tissues. In addition, you should
also adjust the objectives to your prescription by turning the knurled ring
 of the eyepiece. Daily handling can displace the interpupillary distance of the
 oculars, hence a small adjustment could make a big difference with respect to
 viewing comfort and rendering subtle
3D details more evident.

3. Follow the Anatomy A comprehensive SLE should follow a logical
sequence. It's best to begin with low magnification and observe the
 external structures first, such as lids, lashes, inner and outer canthi
 and tear meniscus. You can also evaluate the overall appearance of
the bulbar conjunctiva, cornea, iris and pupilBegin by sweeping the lid margin from the outer canthus towards the inner canthus. Of particular interest for contact lens (CL) wearers is a detailed examination of the lid margin, paying particular attention to the lids, lashes and tear film. Examine the lashes for signs of blepharitis, madarosis (loss of lashes) and trichiasis (misdirected lashes). Observing the tear meniscus should reveal a uniform structure with little debris and an inferior meniscus that's slightly larger than its superior counterpart. Note lid margin scars or deformities, especially if they obstruct the flow of the tears towards the punctum. Meibomian gland expression should require little force and reveal clear liquid secretions. Meibomian gland dysfunction is often underdiagnosed, leading to an unstable tear film and unexplained CL dropout. Make lid eversion a routine part of every anterior segment examination, even more so in CL wearers. Check the lids for signs of papillary response or hyperemia. Some silicone hydrogel lenses that have higher modulus have resulted in a papillary response in some patients. Switching to a lens with lower modulus may have beneficial effects. 

TABLE 1
llumination Techniques
ILLUMINATION	ILLUMINATION ANGLE (DEGREES)	MAGNIFICATION*	TISSUES
Diffuse	30-45	Low	External overall view, lid, lashes, CL fit
Direct:
• Broad beam	30-45	Low-med	Conjunctiva, cornea
• Parallelepiped	30-45	Med	Cornea, meniscus, iris, lens
• Optical Section	30-60	Med	Angle estimation, corneal layers, lenticular layers
• Conical Beam	30-45	Med	Anterior chamber (cells)
Indirect	45-60	Med	Cornea
Retroillumination	0	Low-med	Transillumination of the iris, lenticular opacities direct
Specular Reflection	90 from microscope	Med-high	Tear Layer, endothelium
Sclerotic scatter	60	Low	Corneal scars, central edema
Tangential	70-80	Med	Iris (freckles, suspicious nevi)
* Low: 6X to 10X, Med: 10X to 16X, High: 25X to 40X

A detailed examination of the corneal structures (epithelium, stroma and endothelium) is next, varying magnification and illumination as needed. Examine the iris, pupil and crystalline lens last because the direct illumination is more bothersome for the patient. A systematic SLE will improve efficiency, uncover reasons for CL intolerance, reduce chair time and limit omissions of tissue anomalies.

4. Know Your Illuminations

Can you differentiate between specular reflection and sclerotic scatter? Most practitioners vaguely remember learning about illuminations, but the specifics have developed cobwebs over time. Most of us perform SLE under a somewhat automated mode. We constantly switch from one type of illumination to another without realizing it.

A review of illuminations may be helpful in reminding us of those used less frequently but with inherent advantages. Table 1 offers a quick overview of different illuminations and which structures are best viewed under these illumination techniques. Some slit lamp models have the ability to tilt the illumination column (towards the patient) up to 20 degrees (in 5 degree increments). This oblique illumination is useful in reducing reflections during gonioscopy. In modern slit lamps, manufacturers have replaced most tungsten type bulbs, which have a redder light, with more efficient halogen illumination, which provides a bluer light. Fluorescein is also useful in performing the Seidel test, which identifies aqueous leaking.

5. Enhance Your View

Adding ophthalmic dyes to your SLE will improve your diagnostic evaluation. Sodium fluorescein highlights areas of corneal stress while lissamine green is best at highlighting conjunctival problems. Better tolerated than rose bengal, lissamine green is observed in white light and provides additional insight for patients presenting with dry eye symptomology or CL intolerance.

Document staining, noting the form, depth and extent. The shape of staining can be micropunctate (resembling small dots), macropunctate (larger dots) or coalescent staining (a patch). Its depth can be limited to the epithelium or it may enter the stromal layers. You can approximate the extent in percentage of the surface area affected by the staining. Improving your documentation of staining will facilitate your observation for any progression or regression at follow-up visits.

Table 2
Effect of Magnification on Field of View*
MAGNIFICATION	FIELD OF VIEW
6X	35.1mm
10X	22.5mm
16X	14.1mm
25X	8.8mm
40X	5.6mm
* Using a 12.5X eyepiece

6. Filters

We perform most of a SLE using white light. When using fluorescein, use a yellow (Wratten #12) barrier filter in conjunction with a cobalt (blue) filter to maximize viewing of the fluorescence. Positioning the yellow barrier filter in the path of the returning light and not in the path of the incident light will enhance the contrast significantly. Newer slit lamps have integrated the yellow barrier filter in the ocular housing, as its use is becoming more commonplace.

You can use the red-free (green) filter to differentiate vascular from pigmented lesions. Blood vessels and small hemorrhages will take on a dark appearance with the use of the red-free filter, whereas pigmented lesions will remain dark. Some slit lamps can also be equipped with a neutral density filter and/or a heat-absorbing filter to increase patient comfort.

7. Magnification

Most slit lamp models offer 10X, 16X and 25X magnification, although some models extend to 40X. Most use eyepieces of 10X or 12.5X. As magnification increases, it limits the depth of focus, hence small adjustments with the joystick of the slit lamp will keep the image in sharp focus. Furthermore, increased magnification reduces the field of view (Table 2), allowing for greater detail of structures. Depending on the model, magnification drums can have specified click stops or be continuous. The continuous option, also called zoom system, has the advantage of a smoother transition with no image loss.

If upgrading your biomicroscope is not in your immediate plans, then try extending the magnification by simply purchasing an additional set of oculars (for example, 20X). Returning the magnification to the lowest setting at the end of the examination will reduce prep time for the next patient.

8. Illumination Intensity

Novice users have a tendency to use the highest illumination intensity during the entire examination. The problem is that these habits are hard to break. The examination should begin under the lowest intensity to examine external tissues and to allow the patient to adapt to the illumination, which is even more important if the patient has undergone pupillary dilation. The slit width is often decreased to examine details of ocular tissues under higher magnification. Reserve higher intensity illumination for examining details and use it for a shorter amount of time to conserve energy. You can equally reduce the slit beam height to increase patient comfort during the use of higher illumination intensity.

9. Viewing Angle

During most of the SLE, the observation arm of the slit lamp is directly in front of the patient. You can move the illumination arm to obtain different illumination angles to assess different tissues. Large illumination angles allow you to determine the depth of corneal and lenticular lesions with greater accuracy because the distance between layers of these tissues is increased under these conditions.

To increase the distance between layers even further, make the illumination angle even larger. One way of achieving this is to displace the observation arm from its habitual central position to a more nasal one while extending the illumination column more temporal (Figure 2b). This will enhance your view of the individual layers of the cornea or lens and allow you to determine the depth of lesions with enhanced accuracy.

10. Measuring Eyepiece

Practitioners have traditionally made a subjective evaluation of the height and width of lesions, nevi, staining, meniscus and neovascularization. A measuring eyepiece or graticule can replace a traditional eyepiece to considerably improve this measurement. The eyepiece has a linear and an angular scale, the latter being useful for evaluating toric lens rotation with improved accuracy. With the advent of ocular photography, many offices photograph lesions to properly document problems and to allow for future comparisons. If this capability isn't available in your office, then a measuring eyepiece may considerably enhance your documentation. You can subsequently store the eyepiece for safekeeping and future use.

Final Pearls

SLEs are dynamic. You should have one hand on the joystick and the other available to adjust the illumination arm, magnification, lighting intensity, slit width or even to hold an accessory instrument.

Locking your biomicroscope following examination will prevent unnecessary swinging and possible damage to the mechanics of the slit lamp during positioning towards or away from the patient. Using a dust cover over the slit lamp at the end of the day will help protect your investment.

Knowing the different options (filters; illumination width, height and intensity; magnification) your slit lamp has to offer, coupled with proper maintenance, will ensure a high image quality and help you perform a more efficient SLE.