The Slit Lamp Microscope
The Uses

Notes to accompany lecture to 2nd year City University undergraduates

Dr Simon Barnard PhD BSc FCOptom FAAO DCLP


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 §



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:


Just a few examples of abnormalities diagnosed with slit lamp microscope


Meibonitis, blepharitis,


Pediculosis, distichiasis


Fast "invasive tear break up time"




Infiltrates, pannus


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,


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
  • Tearscopeâ
  • Photography using 35 mm, video or digital systems

Recommended reading

Fingeret M, Casser L, Woodcombe, HT (1990) Atlas of Primary Eyecare Procedures, Appleton & Lange, Norwalk