What are the slit lamp illumination technqiues (10)
Diffuse, parrallelepiped, tangential, optic section, conical beam
Indirect proximal, specular reflection, sclerotic scatter, retroillumination
Van Henrik angle
How to carry out diffuse illumination and what part of the eye does it check
- wide slit with diffuser
- overall view of ocular structures and contact lens centration
How to carry out tangential illumination and what part of the eye does it check
- Meidum to wide slit with low to mid magnification
- to observe surface of iris
How to carry out parallelpiped illumination and what part of the eye does it check
- narrow beam (bigger than optic section) should see two lines
- Evalute depth and extent of corneal abrasions, scarring or foreign bodies (for cornea)
How to carry out optic section illumination and what part of the eye does it check
- reduce width of parallelpiped to extremlyyy thin- see three lines
- estimate depth of abnormality/ determine position of cataract (more detailed view of cornea)
How to carry out conical beam and what part of the eye does it check
- shorten and narrow parallelpiped to produce a circular/ sqaure spot of light with high magnification
- transparency of anterior chamber for evidence of floatnig cells and flare (for anterior chamber)
How to check eyelids and lashes
- moderatly wide illumination beam
how to examine palpebral conjunctiva
- use low magnification
how to examine bulbar conjunctiva
- medium beam width ~ 5mm to scan
how to examine sclera
- moderately wide beam with low to medium maginification w bulbar conjunctiva
Cornea
- optic section, parallelpiped, specular reflection
How to examine anterior chamber
- van henrick
- conical beam
how to examine iris
- tangential
How to examine crystalline lens
- use optic section, could reduce the verticle height
- retroillumination from the retina
How to examine anterior vitreous
- narrow beam (optic section)
How to carry out indirect proximal illumination and what part of the eye does it check
- narrow slit of 1 to 2mm where the beam is focused next to ocular tissue observed (optic section)
- observe structure next to the focused light beam
How to carry out specular reflection and what part of the eye does it check
- seperate microscope around 60 degrees, shine at the cornea
- to check the endothelial cells (if darker than surrounding then
How to carry out sclerotic scatter and what part of the eye does it check
- bright, narrow slit beam on limbus
- halo around the iris
How to carry out retro illumination and what part of the eye does it check
- reflect light of a slit beam that is posterior to object
- vertical slit beam to 1 to 4mm wide (parallelpiped)
- to see sclera blood vessels
How to carry out van henrick angle and what part of the eye does it check
- judge the depth of the anterior chamber near the angle
- ascertain the risk of angle closure glaucoma
What is the grading of the van henrick angles
1:1 grade 4
1: 1/2 grade 3
1: 1/4 grade 2
1: <1/4 grade 1
