slit lamp illumination techniques

Slit Lamp Illumination Techniques

Author: Irina Jagiloviča

e-mail: [email protected]

www: www.optometristiem.lv

Diffuse Illumination

Light is spread evenly over the entire observed surface

The beam is opened all the way.

Direct the light onto the eye at a 45 degree angle

The microscope is directed straight ahead.

Observe: eyelids, lashes, conjunctiva, sclera, pattern of redness, iris, pupil, gross pathology, and media opacities

Diffuse Illumination

Direct Illumination Techniques

Beam The microscope is usually directed straight ahead but may also be moved to an

angle opposite the illuminator. The greater the angle between the illuminator and the microscope, the greater the

width of the illuminated section. A very narrow beam (optical section) directed onto the cornea can be used to

evaluate corneal shape, elevation, and thickness. Observe: cornea, iris, lens, vitreous

Tangential Illumination

This technique is used to observe surface texture. Medium-wide beam of moderate height Swing the slit lamp arm to the side at an oblique angle Magnifications of 10X, 16X, or 25X are used Observe: anterior and posterior cornea, iris, anterior lens (especially useful for

viewing pseudoexfoliation)

Tangential Illumination

Specular Reflection

Specular reflection is used to visualize the integrity of the corneal and lens surfaces. If the surface is smooth, the reflection will be smooth and regular; if the surface is broken or rough

Position the illuminator about 30 degrees to one side and the microscope 30 degrees to the other side

To visualize the endothelium, start with lower magnification (10X to 16X). Direct a relatively narrow beam onto the cornea

Switch to the highest magnification available.

Endothelium is best viewed using only one ocular, so you may want to close one eye.

Observe: corneal epithelium and endothelium, endothelial mosaic, lens surfaces

Specular Reflection

Indirect Illumination

Proximal

Use a short, fairly narrow slit beam.

Place the beam at the border of the structure or pathology

Observe: corneal opacities (infiltrates, vessels, foreign bodies)

Proximal

Sclerotic Scatter

A tall, wide beam is directed onto the limbal area.

When the light is properly aligned with regard to the eye, a ring of light will appear around the cornea.

The light is absorbed and scattered through the cornea

highlighting pathology.

Use 10X magnification, with the microscope directed straight ahead

Observe: general pattern of corneal opacities

Sclerotic Scatter

Retroillumination

Retroillumination is used to evaluate the optical qualities of a structure.

The light strikes the object of interest from a point behind the object and is then reflected back to the observer

Retroillumination

Indirect Retroillumination from the Iris

the beam is directed to an area of the iris bordering the portion of the iris behind the pathology

This provides a dark background, allowing corneal opacities to be viewed with more contrast

Retroillumination from the Fundus (Red Reflex)

The slit beam at 2 to 4 degrees

Shorten the beam to the height of the pupil to avoid reflecting the bright light off of the iris.

Focus the microscope directly on the pathology using 10X to 16X magnification. Opacities will appear in silhouette.

This view is best accomplished if the pupil is dilated.

Retroillumination From the Fundus (Red Reflex)

Van Herrick Technique

Use to evaluate anterior chamber angle without gonioscopy Medium magnification Angle 60 degrees Narrow beam close to limbus

Depth of anterior chamber is evaluated it to the thickness of cornea:

4. grade – open anterior chamber angle 1:1 ratio

3. grade – open anterior chamber angle 1:2 ratio

2. grade – narrow anterior chamber angle1:4 ratio

1. grade – risky narrow anterior chamber angle less than 1:4 ratio

0. grade – closed anterior chamber , cornea “sits” on iris


1. grade – risky narrow anterior chamber angle less than 1:4 ratio

Thank you !

slit lamp illumination techniques

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