Indications:

• This should be performed on all patients with ophthalmology presentation
• Specifically – red eye, loss of visual acuity, ocular pain, suspected conjunctival foreign body, suspected corneal foreign body

Contraindications:

• Unable to open eye
• Unable to sit for assessment – children
• Globe rupture – place no pressure on the eye
• Caustic exposure

Alternatives:

• Assessment under vision without a slit lamp
• US assessment of the globe
• CT of orbits

Consent: Verbal consent is enough, low risk of complications

Potential complications:

• Pain, photophobia
• Failure of assessment
• Corneal abrasion

Infection control:

• Standard precautions
• PPE – non-sterile gloves

Area – darkened room with the slit lamp

Staff – proceduralist

Equipment  – slit lamp

Anatomy of a Slit lamp (Image courtesy eyewiki.com)

The following instructions are meant to provide a quick reference for conducting a slit lamp examination (see Figure above.)

• Ensure that the slit lamp is plugged in
• Clean forehead and chin rest
• Bring the table into position in front of the patient
• Adjust the chin height to position the eyes at the level of the black indicator line with the head in contact with the forehead band
• The patient can be instructed to hold the handlebars
• Set oculars at ‘0’ and adjust interpupillary distance like binoculars
• Unlock the carriage
• Adjust coarse focus by moving the entire carriage forward and backward at the base.
• Move the joystick into position: turn clockwise to raise, counterclockwise to lower, fine focus in X and Y planes.
• Turn the power switch on (below the table)
• Adjust beam width and intensity
• Set the light on the correct filter (white light or neutral density for general exam, cobalt-blue for fluorescein)
• Adjust the height of the beam.
• Move the beam angle by swivelling the illumination area while grasping the beam width knob
• For general exams, do not adjust the decentering screw as it can result in loss of parfocality
• At the conclusion of the exam, lock the carriage in place
• Turn off the slit lamp power switch

Positioning:

• Patient sitting comfortably at slip lamp
• Chin on chin rest
• Forehead firmly against the headrest

Medications:

• Local anaesthetic drops – improve control
• Fluorescein 1-2% drops or Fluorescein paper

Slit lamp preparation ;

• Adjust the chair and table heights for comfort
• Turn the slit lamp on – the switch is underneath the table
• Adjust binoculars for your comfort
• Adjust the chin rest to align the patient’s eye level with the black line
• Set the light filter to produce bright white light angles at 45 degrees
• Increase light beam height by rotating the top dial on the illuminator tower
• Note that turning this dial fully until it clicks produces a blue light used for the fluorescein exam
• Set the width to 1 mm to 10 on the scale on the bottom dial on the moving arm

Examination of the eye:

• Examine the unaffected eye without Fluorescein – lashes, lids, conjunctiva, sclera, cornea, anterior chamber, iris, lens
• Begin with coarse focusing without using the microscope
• Move the whole slit lamp base, then in focus, move to the microscope
• Adjust the focus with the joystick

How to use a slit lamp (video courtesy Emin5.com)

Discussion:

The slit lamp is very useful in ED to diagnose corneal epithelial defect, corneal and conjunctival foreign bodies, keratoconjunctivitis, hyphemia, hypopyon, lens dislocation, herpetic infection, iritis or evaluation of red eye.