B10 Flashcards
(124 cards)
What kind of image does a BIO give you?
Real, inverted, and lateral reversed image formed in front of the lens
Why is BIO considered indirect?
Because the fundus is seen through a condensing lens
The image for BIO is formed close to the ____ between the lens and the observer
Principle focus of the lens
Higher power lenses offer ____FOV and can aid with examination through ___ pupils
Greater FOV and aid through small pupils
This lens is a good balance between magnification and FOV
20D lens
What 3 things does the power of the condensing lens determine?
- working distance
- magnification
- FOV
As the power of the condensing lens decreases, the FOV ___ but the working distance and magnification ____
FOV decreases, working distance and mag increases
For a 30 power lens What is the mag? What is the FOV? What is the stereo? What is the working distance from the cornea?
Mag: 2x
FOV: 60 degrees
Stereo: 1/2
Working distance: 26mm
For a 20 power lens What is the mag? What is the FOV? What is the stereo? What is the working distance from the cornea?
Mag: 3.25x
FOV: 40 degrees
Stereo: 3/4
Working distance: 47mm
For a 14/15 power lens What is the mag? What is the FOV? What is the stereo? What is the working distance from the cornea?
Mag: 4.17x
FOV: 30 degrees
Stereo: 1
Working distance: 72mm
Lens used to obtain a panoramic view when detail and stereopsis are not as important, and used with small pupil
30D lens
Which lens has the shortest working distance?
+30 lens
most widely lens used, since it provides an adequate field of view, stereopsis and magnification
20D lens
lens is most useful for detailed view of the macula or optic disc or for determining elevation of the retina in shallow retinal detachment
15D lens
What kind of lighting do you use for BIO?
Dim lighting; enough to achieve sufficient contrast
T/F: begin with the brightest light when doing BIO
False. Start lower and gradually turn it up to double check the selected area
T/F: have a sequential system for BIO
True, look in one quadrant and proceed to the next
What are the 7 advantages of BIO?
- Image is not affected by the patient’s refractive power
- Great for eyes with nystagmus
- Great for use in children
- Portable
- BIO allows for examination into the far periphery
- Large field of view
- Stereopsis
Disadvantages of BIO
-Difficult to learn
-Less magnification, therefore details of a small lesion not visualized
properly
-Impossible with very small pupils
-More uncomfortable for some patients
What are the advantages of having a systemic approach?
-Minimizing the risk of overlooking any area of the ocular fundus
-Aiding in the recall of the location of findings that are
recorded at the conclusion of the examination
The recommended approach is to complete the
examination of the ___ eye before beginning the ___eye
OD before OS
T/F: The peripheral fundus is usually examined before the posterior pole to allow the patient some time to light adapt
True
How many meridians are there when examining the fundus?
8
How do you need to stand when examining the periphery?
180 degrees away from the meridian that you wish to examine