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Slit Lamp Illumination Techniques

 Author: Irina Jagiloviča 

e-mail: irina.jagilovica@gmail.com

www: www.optometristiem.lv

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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

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Diffuse Illumination

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Diffuse Illumination

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Direct Illumination Techniques

Beam

The microscope is usually directed straight ahead but may also be moved to anangle 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 toevaluate corneal shape, elevation, and thickness.

Observe: cornea, iris, lens, vitreous

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Beam

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Beam

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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)

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Tangential Illumination

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Specular Reflection

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

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

To visualize the endothelium, start with lower magnification (10X to 16X). Direct arelatively 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 oneeye.

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

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Specular Reflection

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Specular Reflection

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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)

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Proximal

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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 willappear around the cornea.

The light is absorbed and scattered through the corneahighlighting pathology.

Use 10X magnification, with the microscope directed straight ahead

Observe: general pattern of corneal opacities 

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Sclerotic Scatter 

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Sclerotic Scatter 

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Sclerotic Scatter 

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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 thenreflected back to the observer 

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Retroillumination

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Indirect Retroillumination from the Iris

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

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

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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 16Xmagnification. Opacities will appear in silhouette.

This view is best accomplished if the pupil is dilated.

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Retroillumination From the Fundus (Red Reflex)

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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 ratio0. grade – closed anterior chamber , cornea “sits” on iris 

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Van Herrick Technique

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Van Herrick Technique

1. grade  – risky narrow 

anterior chamber angleless than 1:4 ratio

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Thank you !