Faculty of optometry &visual sciences
Photography & eye imaging 4th year
Lecture no (6)
Slit lamp photography +Specular microscopy
Uz: Sulma Yagoob Abdalla
(MSc primary eye care optometrist)
• Slit lamp biomicroscope, as a photographic instrument, uses
focal illumination to high light examination of the anterior
segment of the eye.
• The ophthalmic photographer must learn :
➢ How to use the equipment.
➢ Recognize normal anterior segment anatomy and pathology .
➢ Have the photographic knowledge to record these conditions
on film .
• The slit lamp illuminator
• Optical head : the ability to view changes in the light beam’s
position is controlled by the optical head of slit lamp.
• Its provides the photographer with a binocular, magnified,
three dimensional view.
❖ Accessories unique to photo slit lamps:
➢ Electronic flash
➢ Background diffuse illuminator
➢ beam splitter: the ability to view through the optical head
and photograph at the same time is made possible through
the use of beam splitter which produces two images with the
aid of a combination prisms.
➢ The camera body: the image quality is a function of the optics of
the photo slit lamp rather than the camera used.
➢ Reticule in eyepiece: is necessary as a reference point to achieve
sharply focused photographs. Is located in the ocular on the same
side of the beam splitter.
➢ Exposure affected by:
1. The type of the film (fast film low magnification & vice versa).
2. Texture of the lesion.
3. Magnification if increase we can increase exposure.
4. Dark or light area be photographed.
Slit lamp biomicroscopy
• It composed of :
• Illumination system : the slit can be varied in both height and width
and can be supplemented with filters;
➢ Diffuser filter
➢ Cobalt filter
➢ Red-free filter
➢ Neutral density filter
➢ Yellow filter
• Observational system
• Mechanical system
Types of illuminations
• Diffuse illumination: a wide beam is used, low magnification
(6x) to obtain general overview of the eye.
• The structured to be viewed with this technique include: the
lids, lid margins, puncta, eyelashes, bulbar & palpebral
conjunctiva, cornea, pupil, iris and precorneal tear film.
• Direct focal illumination DFI : both slit beam and microscope
are focused at the same point.
• DFI (paralle piped); 1-2mm beam width, allows structures to
be viewed in three dimensional
• We can observed : tear deris, corneal nerves, abrasions ,
scars, straie , ghost and blood vessels, crystalline lens,
• DFI optic section: formed with a narrow beam 0.2- 0.3mm in
width and 60 angle between illumination and observation
• When viewing a corneal optic section the anterior bright band
is the tear film layer and epithelium and the posterior bright
band is the endothelium while the thicker dim band between
these two bright layers is corneal stroma.
• This illumination also can be used to estimate the depth of
the anterior chamber.
❑ Sclerotic scatter : this produce by the total internal reflection
occurs within the cornea as light directed onto the limbus.
❑ Sclerotic scatter used to highlight pathology that involves a
majority of the cornea rather than a small isolated area.
• Refers to the technique of illuminating pathology and conditions not by
light that falls directly on it but rather by light that stikes an uninvolved
area of the eye first. Bouncing the light off this area redirects it to the
desired site from an angle not possible with direct illumination.
❑ Retroillumination :
➢ Retroillumination from the iris .
➢ Retroillumination from the retina.
➢ Retroillumination is best achieved by using a slit beam equal in height to
the surface the slit beam is to be passed the reflected off.
retro-illumination from the iris
• Don’t dilate pupil.
• Place light carefully to observe corneal pathology
when reflected from iris.
• Adjust slit illuminator to tall wide beam.
• It best achieved by using slit equal in height to
Using the photo slit lamp
• 1. establishing a system
• 2. patient management
• 3. alignment of the photo slit lamp
• 4 . Magnification : most photo slit lamps have a magnification range of 6x-
25x although some go as high as 40 x.
• Lighting techniques such as diffuse, optical section with diffuse or sclerotic
scatter are used to show the entire cornea with 6x- 16x magnification.
• Optical section broad beam , tangential and retroillumination are used to
show more specific areas and tend to work best with magnifications 16x-
• 5. orientaion of 35mm camera.
• 6. color slide film produces a color positive image and it is the standard for
use in the photo slit lamp.
• Corneal endothelial cells act as a metabolic pump to balance the amount of
water in the stroma of the cornea to maintain its clarity.
• When corneal endothelial cells die they do not regenerate. The remaining cells
swell in size and fill the space vacated by dead cell.
• The central corneal endothelium changes as a person ages. From age 20 to 50
the endothelial cell density remains stable for most people .
• Beyond age 50 a slow decline begins. By age 60 most people experience a
significant reduction in endothelium cell density.
• Specular microscope is a special instrument that allows the photographer or
specialist to see and record the corneal endothelium cells.
• Specular microscopy is a noninvasive photographic technique that allows to
visualize and analyze the corneal endothelium.
• Its analyze the size, shape and population of the endothelial cells.
• There are three instruments used to imaging and recording the
appearance of the corneal endothelium.
1. The clinical slit lamp/ photo slit lamp
2. The non-contact specular micoscope: have much less
magnification which may prevent seeing good cell detail. They
may be much easier to use in difficult patients.
3. Contact specular microscope: requires that the patient’s cornea
be anesthetized with eye drops. The patient’s head is then placed
into a frame with a chinrest which controls movement. The
endothelium cells are brought into focus and easier to photograph
Its quick procedure and have more magnification but difficult to use in
difficult cases as children .
• Technique of slit lamp when used to image endothelium :
• The angle of the slit beam and the position of the observer
coincident with the optic head of the slit lamp that is with the
patient gazing straight a head the slit beam is 30 degree to the
right side and the optical head 30 to the left axis of fixation.
• Magnification: using the highest available magnification or
adding a specular magnifying eyepiece.
• To see endothelium:
✓ The first step is to place the slit beam lower at 30
from the central axis of fixation
✓ Then sweep the cornea until the bright reflex is seen,
this will happen because at some point the angle of
incidence is equal to the angle of reflection.
✓ The first step should be performed at low
magnification, when bright reflex is seen the cells can
be seen adjacent to the reflex by increasing
magnification and focusing more posterior than the
• Ophthalmologist want a cell count to evaluate a patient prior
to cataract surgery.
• Suspious change in the appearance or thickness of the cornea.
• Eye and tissue banks routinely use the specular micoscope to
evaluating a doner cornea prior to corneal transplant
• Contact lens patients.