Slit Lamp Examination-Illumination Basics

Editorial

J Ophthalmol & Vis Sci. 2019; 4(1): 1032.

Slit Lamp Examination-Illumination Basics

Chauhan A*

Department of Ophthalmology, Dr Yashwant Singh Parmar Governament Medical College, India

*Corresponding author: Anubhav Chauhan, Department of Ophthalmology, Dr Yashwant Singh Parmar Governament Medical College, India

Received: October 28, 2019; Accepted: December 16, 2019; Published: December 23, 2019

Editorial

1. Direct Illumination (Diffuse, Focal, Specular).

2. Indirect Illumination (Proximal, Retroillumination, Sclerotic Scatter).

1. Direct Illumination (Slit beam is focussed on the area of interest).

Table 1a: Diffuse Illumination





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (Opened to) 

    
Full 

  

  

    
Illumination (Intensity of light) 

    
Minimum to moderate (use neutral density filter) 

  

  

    
Angle of slit beam and microscope 

    
45 Degree 

  

  

    
Magnification 

    
6x-10x 

  

  

    
Uses 

    
Broad examination of eye 

  










Table 1a: Diffuse Illumination

Table 1b: Focal Illumination Broad beam:





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (Opened To) 

    
2mm Wide 

  

  

    
Illumination (Intensity Of Light) 

    
Maximum 

  

  

    
Angle of slit beam and microscope 

    
45 Degree 

  

  

    
Magnification 

    
10x-30x 

  

  

    
Uses 

    
Surface texture (E.G. corneal epithelium to endothelium changes,    corneal abrasions, corneal nerves, iris and lens anomalies) 

  










Table 1b: Focal Illumination
Broad beam:

Narrow beam:





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (Opened To) 

    
Narrow to minimum width 

  

  

    
Illumination (Intensity Of Light) 

    
Maximum 

  

  

    
Angle of slit beam and microscope 

    
45 Degree 

  

  

    
Magnification 

    
16x-30x 

  

  

    
Uses 

    
Density of lesions/opacities (e.g. corneal lesions-depth/thickness,    anterior chamber depth, anomalies of iris, lens, vitreous) 

  










Narrow beam:

Conical beam:





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (opened to) 

    
Height and beam narrowed to smallest uniform section. 

  

  

    
Illumination (Intensity of light) 

    
Maximum 

  

  

    
Angle of slit beam and microscope 

    
45 Degree 

  

  

    
Magnification 

    
40x 

  

  

    
Uses 

    
Detect suspended particles in liquid (E.G. cells and flare in uveitis) 

  










Conical beam:

Specular reflection:





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (opened to) 

    
2mm wide 

  

  

    
Illumination (Intensity of light) 

    
Maximum 

  

  

    
Angle of slit beam and microscope 

    
Illuminator 30 Degree to one side and microscope 30 degree to the    other. 

  

  

    
Magnification 

    
10x-16x 

  

  

    
Uses 

    
Integrity of cornea and lens surfaces (e.g. corneal endothelium    visualization) 

  










Specular reflection:

Table 3: Indirect illumination (Slit beam is focused just beside the area of interest). 3a. Proximal.





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (opened to) 

    
Narrow beam 

  

  

    
Illumination (Intensity of light) 

    
Maximum 

  

  

    
Angle of slit beam and microscope 

    
Illuminator 30 Degree to one side and microscope 30 degree to the    other. 

  

  

    
Magnification 

    
16x 

  

  

    
Uses 

    
Depth and density of lesion (e.g. lesions of cornea, iris, lens) 

  










Table 3: Indirect illumination (Slit beam is focused just beside the area of interest).
3a. Proximal.

Table 3b: Retroillumination. • Direct retroillumination from iris.





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (opened to) 

    
Moderate wide beam 

  

  

    
Illumination (intensity of light) 

    
Maximum 

  

  

    
Angle of slit beam and microscope 

    
Moderate to maximum (slit aimed towards iris just behind corneal    abnormality) 

  

  

    
Magnification 

    
16x 

  

  

    
Uses 

    
Lesions of cornea (e.g. keratic precipitates) 

  










Table 3b: Retroillumination.
• Direct retroillumination from iris.

• Indirect retroillumination from iris (same as above i.e. b(aa) but slit beam is focussed at the limbus (e.g. grade the anterior chamber angle) • Retroillumination from fundus.





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (opened to) 

    
2mm Wide and height just equal to pupil 

  

  

    
Illumination (Intensity of light) 

    
Moderate to maximum 

  

  

    
Angle of slit beam and microscope 

    
Slit beam and microscope being coaxial 

  

  

    
Magnification 

    
16x 

  

  

    
Uses 

    
Lesions of cornea, lens and vitreous (e.g. opacities) 

  










 • Indirect retroillumination from iris (same as above i.e. b(aa) but
slit beam is focussed at the limbus (e.g. grade the anterior chamber angle)
• Retroillumination from fundus.

Table 3c: Sclerotic scatter.





  

    
Parameters 

    
Adjustments 

  

  

    
Slit beam (opened to) 

    
1 mm and focussed adjacent to the limbus. 

  

  

    
Illumination (Intensity of light) 

    
Maximum 

  

  

    
Angle of slit beam and microscope 

    
60 Degree 

  

  

    
Magnification 

    
16x 

  

  

    
Uses 

    
Lesions of cornea 

  










Table 3c: Sclerotic scatter.

Citation: Chauhan A. Slit Lamp Examination-Illumination Basics. J Ophthalmol & Vis Sci. 2019; 4(1): 1032.