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Optometry
Gonioscopy- lens
24
Other
Graduate
01/31/2013

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Cards

Term
Gonioscopy
Definition
means to view the angle. uses CLs that neutralize corneal refractive power and negates internal reflections of chamber angle.
Term
Direct view on Gonioscopy uses
Definition

simple light refraction

 

Term
what does the indirect view in gonioscopy use
Definition
mirrors to reflect light
Term
what is most frequently used for direct view and what type of image is produced
Definition
Koeppe lens: 50D concave base lens with convex bubble-shape outer surface
Term
which view is used more often and what kind of image is produced?
Definition

indirect view.

Image is inirect, virtual and unmagnified

Term
what are the advantages of the indirect view in Gonioscopy?
Definition

uses an optic section to identify structures (eg: schwalbe's line)

  • can vary magnification with slit lamp
  • bright illumination from slit lamp allows to see samll details,
  • easy implementation during examination,
  • laser treatment
Term
Disadvantages of indirect
Definition

patient discomfort, small field of view and poor lateral view,

need fluid,

artifacts and corneal folds can sitort view, can have error in diagnosis secondary to pressure from the lens,

may produce anle opening or narrowing.

Term
how to get improved view of angle recess with indirect view gonioscopy?
Definition

tilt the lens toward angle of observation and/or

have pt look toward the gonio mirror examiner is observing

Term
How many times do you have to rotate a 1 mirror goldmann-style lens?
Definition
rotate it 3 times to view entire angle
Term
How many times do you have to rotate a 2 mirror goldmann-style lens?
Definition
rotate it once to evaluate the whole angle
Term
what are the advantages of 1 and 2 mirror lens?
Definition
  • smaller lens (good for small aperture pt or squeezers)
  • lighter lens
  • mirrors located closer to center of lens: this makes for a higher vantage point for angle observation and easier to see angle recess over bowed iris or natural angle.
Term
what are the advantages of the 4-mirror lens?
Definition

4 viewing mirrors means no lens rotation necessary.

  • tear is the interface medium,
  • smaller radius of curvature on CL-- more useful for indentaation
  • quick assesment
Term
what are the disadvantages of the 4-mirror lens?
Definition
  • pt cooperation necessary
  • requires steady hand and a lot of practice,
  • distortion of normal angle configuration is possible,
  • corneal folds are easily induced.
  • no peripheral retinal examination capabilities.
Term

what is the best choice for new to gonio people?

 

Definition

goldmann 3 mirror lens:

Gonio soln helps to keep stability of lens position

angle structures less crowded, easier to differentiate.

Term
What does the central mirror view in a 3-mirror lens?
Definition

view of central 30deg of  posterior pol.

not inverted or reverse,

actual direct view

Term
What does the trapezoid mirror view in a 3-mirror lens?
Definition
equatorial region of retina with dilated patient
Term
What does the rectangular  mirror view in a 3-mirror lens?
Definition
peripheral fundus anterior to equator (rectangle has 2 equal sides) with dilated pt
Term
what does the thumbnail mirror show?
Definition
view of angle (undilated)and ora seratta (dilated)
Term
indications for gonioscopy
Definition

retinal evaluation (stereo view of pesterior pole through ora,

prob based test to view lesion seen with BIO.

dfe for uncorporative pt.

Term
for the 3 way lens peripheral rectangular mirror what is difference between image and actual?
Definition

looking at mirror image so the views are inverted only!

(not inverted and reversed laterally like BIO)

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