The Uses of the Slit Lamp Biomicroscope

The Slit Lamp Microscope

The Uses

Bottom of Form 1

Notes to accompany lecture to 2nd year City University undergraduates

Dr Simon Barnard PhD BSc FCOptom FAAO DCLP

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Table of Contents

Table of Contents***

Introduction***

Key objective***

Uses of slit lamp***

Routine observation of ocular adnexia***

Methods of illumination***

Investigation of posterior segment***

Advantages of BIO***

Monitoring signs and symptoms***

Further "special investigations" ***

Recommended reading***

Introduction

The ability to carry out expert slit lamp microscopy can only be attained by extensive practise of the techniques in conjunction with:

A familiarity with the instrument and its controls
An understanding of the normal anatomy of the anterior (and posterior) eye
A knowledge of the range of "normal" appearances seen in patients.

Key objective

To introduce the practitioner to the various clinical uses for which the slit lamp biomicroscope is employed.

Uses of slit lamp

The slit lamp biomicroscope is used extensively during optometric/ophthalmological procedures:

Routine observation of ocular adnexia
Routine investigation of posterior segment
Monitoring signs and symptoms of anterior segment conditions
Further "special" investigations

The instrument has a specific role to play in the field of contact lens practise:

To help establish if a patient is suitable for contact lens wear
During the routine examination of contact lens patients

Routine observation of ocular adnexia

The slit lamp is used to examine the "external eye:

Structure / Just a few examples of abnormalities diagnosed with slit lamp microscope
Lids / Meibonitis, blepharitis,
Lashes / Pediculosis, distichiasis
Tears / Fast "invasive tear break up time"
Conjunctiva / Conjunctivitis
Cornea / Infiltrates, pannus
Pupil / Anomalous pupillary responses
Anterior segment structures / Iris thinning
Anterior chamber angle / Narrow anterior chamber angle

Methods of illumination

Whilst methods of illumination have been discussed in a previous lecture (see lecture by Mrs J Birch) a brief review is listed here:

Direct, indirect, direct retro-, indirect retro-,

sclerotic scatter, specular reflection,

trans-illuminance.

You are reminded that it is important not just to consider the method of illumination but how each helps you see ocular structures and tissue changes.

For example:

a narrow cone of light is passed through the aqueous in a completely darkened room, to detect aqueous flare/cells
sclerotic scatter is used to detect subtle intracorneal lesions
specular reflection is used to examine fine cellular architecture of the corneal endothelium

Investigation of posterior segment

The following lenses have been/or are used in conjunction with the slit lamp biomicroscope:

Hruby lens (-55D)

El Bayadi lens (+ve sph)

Other high plus aspheric lenses e.g., Volk lenses ( various +)

Goldman and other design contact lenses

Advantages of BIO

e.g., Volk aspheric biconvex lens (+60, +78, +90 and +138D)

Independent of refractive error (c.f. –20 myope examined by direct ophthalmoscopy
Media opacities incidental so helpful when viewing fundi through cataract
Excellent field of view e.g., +90 Superfield = 120 c.f. direct ophthalmoscopy
Stereoscopic view ideal for differentiating positions of lesions e.g., differentiate IRMA and retinal neovascularisation in diabetic retinopathy.

Monitoring signs and symptoms

Examples of symptom/signs for which the slit lamp is invaluable include:

red eye
painful eye
gritty/dry eye
itchy eye
epiphora

Always instil fluorescein when investigating the above signs/symptoms.

Further "special investigations" investigations

There are number of other investigative techniques that utilise the slit lamp. Some of these utilise attachments or additional equipment used in conjunction with the slit lamp. Examples of these include

Goldman tonometry
Van Herick’s technique
Gonioscopic examination of the anterior chamber
Pachometry
Tearscope
Photography using 35 mm, video or digital systems