Slit Lamp

Aka: Slit Lamp

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II. Technique: Slit Lamp set-up

  1. Turn on Slit Lamp light source
    1. Typically 2 switches (one on the unit under the table and one on the overall power supply)
  2. Eye pieces
    1. Position eye pieces for examiner pupilary distance (distance between eyes)
    2. Zero the individual eye piece optics (diopter power)
  3. Set magnification
    1. Start with 10x power (also typically offers a 25x power)
  4. Unlock table microscope and joystick
    1. Unscrew the lock menanism so that the joystick freely moves the microscope
  5. Adjust the light source with 2 knobs on the light source base
    1. Use one knob to adjust the horizontal width to be narrow
    2. Use one knob to adjust the vertical height to be tall
  6. Reset the light filter
    1. Reset the filter adjustment to white (from blue or green)

III. Technique: Positioning

  1. Examiner sets their position first
    1. Set the chair height
    2. Set the swivel arm height of the Slit Lamp table for examiner comfort
  2. Adjust patient position next
    1. Adjust patient seat height
    2. Patient rests chin and forehead against their respective braces on the Slit Lamp
    3. Each lateral canthus should be level with the black marks on the vertical bars to either side of the forehead brace
    4. Some obese patients may be better positioned by leaning forward and down further into the microscope

IV. Exam: General

  1. External
    1. Examine the Cheek, nose and brow for Periorbital Cellulitis, stye
  2. Lids and lashes
    1. Evert the lower lid (and upper lid if foreign body suspected)
    2. Observe for Blepharitis, lesions under lids
  3. Conjunctiva and Sclera
    1. Examine vessels
    2. Observe for Chemosis, Hemorrhage
  4. Cornea
    1. Slit Lamp allows for visualization of Cornea in cross-section and assessing lesion depth
      1. Two light reflections (one front of Cornea and the other, the back of Cornea)
    2. Observe for Corneal thinning, ulceration, abrasion, Laceration, infiltrate, keratitic precipitates
  5. Anterior chamber
    1. Defects are best seen by using the black pupil background behind the Cornea and iris
    2. Observe for anterior chamber cells and flare (cloudiness) in anterior chamber using bright light against dark pupil
    3. Observe for Hyphema, hypopion
  6. Iris
    1. Observe for Melanoma, blood, neovascularization (Diabetes Mellitus)
  7. Lens
    1. Visualization of lens is similar to Cornea with the Slit Lamp allowing a cross-sectional view
      1. Two light reflections (one front of lens and the other, the back of lens, with the lens nucleus between)
    2. Evaluate for Cataract
  8. Vitreous humor
    1. Typically dark unless findings present
    2. Evaluate for vitreous leaking around lens (e.g. lens detachment) or Vitreous Detachment

V. Exam: Blue Filter

  1. Fluorescein Exam
    1. Corneal Abrasion: Highlighted with Fluorescein
    2. Globe Rupture: Fluorescein dilution will occur at the rupture site (Seidel Test)
  2. Applanation Tonometry
    1. Tonometer is pushed onto the anesthetized surface of the Cornea, over the pupil
    2. Tonometer pressure against the eye using a fine adjustment knob labeled with increments 0-1-2-3...
      1. Adjusted until the circle of globe flattening is at 3.06mm mark
      2. Slit Lamp facilitates Tonometry with built in prism whereby examiner simply lines up an inner meniscus
    3. Once aligned, the eye pressure is read from the fine adjustment knob

VI. Exam: Green Filter (Red-Free Filter)

  1. Darkens red lesions
  2. Allows for best visualization of red lesions or vascular lesions on the eye

VII. Exam: Anterior Chamber by Ophthalmology

  1. Gonioscopy
    1. Anterior chamber angle of eye evaluation on Slit Lamp by Opthalmology
    2. Specialized Contact Lens typically used to help evaluate the anterior chamber angle
  2. Other measures
    1. Ultrasound Biomicroscopy
    2. Anterior Segment Optical Coherence Tomography
    3. Scleral Transilluminator

VIII. Resources

  1. Slit Lamp Exam Procedure
    1. http://www.ophthobook.com/videos/slit-lamp-exam-video

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