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Gonioscope

Different types of Gonioscopes:

Direct gonioscopes (Goniolenses)

Indirect gonioscopes (Goniomirror)

  1. Koeppe
  2. Richardon-Shaffer
  3. Layden
  4. Barkan
  5. Thorpe
  6. Swan-Jacob
  1. Goldman Single Mirror
  2. Zeiss four Mirror
  3. Posner four Mirror
  4. Sussman four Mirror
  5. Thorpe four Mirror
  6. Ritch trabeculoplasty lens

Indirect Gonioscopes

Scleral Type: Goldmann= Stabilises the gloves, so used for argon laser trabeculoplasty

Corneal Type: Zeiss= Doesn’t stabilises the glove, so donot used for argon laser trabeculoplasty.

Comparision between Direct & Indirect Gonioscopy

 

Direct Gonioscopy

Indirect Gonioscopy

 

 

Advantages

  1. Provides natural view
  2. Resultant image is erect, so useful for goniotomies
  3. No distortion of angle structures
  4. Good Binocularity is maintained
  5. Variation of angle of visualisation
  6. Possiblity of examining both eyes simultaneously
  1. Can be performed on the slit lamp in outpatient department.
  2. Gives excellent view and easy to use.
  3. Slitlamp beam creats an optical corneal edge, which is useful in identifying the angle structures.
  4. Allows indentation / compression gonioscopy.
  5. Less time consuming.
  6. Especially useful for laser application.

 

 

Disadvantages

  1. Cubersome & inconvenient
  2. Requires patients to be in supine position in aspecial room with special equipment, seldom available in routine OPD
  3. Angle can also be falsely closed if undue pressure is applied on the lens.
  4. Provide less magnificaton & poor details
  5. Now a days only applied in congenital glaucoma surgery.
  1. False closure of angle by pressure can occur.
  2. Artificial widening of angle during use of the corneal type of lense.
  3. Inverted image, opp angle is viewed.
  4. Inability to see both angle simultaneously
  5. Use of viscous fluid with the goldman type of lens makes the cornea hazy.
  6. Can only be used with a slit lamp
  7. Poor stereoscopic lateral view.

Structures Seen in Gonioscopy from posterior to anterior:

Mnemonic: I can see till Schwalbe's Line

I Iris Root(IR)

Can Cilliary Body(CB)

See Scleral Spur(SS)

Till Trabecular Meshwork(TM)

Schwalbe’s Line (SL)

Grading of Anterior chamber angle

Shaffer System

Grade

Angle Width

Configuration

Chance of Closure

Structures Visible

0

0

Closed

Closed

None

I

10

Very Narrow

High

SL only

II

20

Moderately Narrow

Possible

SL to TM

III

20-35

Open Angle

NIL

SL to SP

IV

35-45

Wide open

NIL

SL to CB