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What are the uses of BIO?
- Stereoscopic binocular view
- View of extreme periphery of fundus
- Larger FOV= 12mm or 8 disc diameters
- Clear fundus view irrespective of high ametropia, hazy ocular media or lenticular opacities
What are the risks of BIO?
very bright light- 40 continuos seconds in the same area
What are the characterisitics of the image that is formed?
inverted and reversed
How is a stereoscopic view formed in BIO?
prisms that decrease PD of practioner
What does the silver ring on the CL indicate?
- pointed towards the px
- least convex side
What are the advantages of a yellow CL?
better tolerated by px- blocks blue light- mininally affects fundus colour
What are the advantages of a lower magnification CL?
- greater FOV
- c/d ratio
- macular lesions
What are the advantages of a higher magnification CL?
- scanning the macula
- px with smaller pupils
What are the reasons why a image may appear dimmer with BIO?
- image of light source defocused- less light going into pupil- defocosed fundus image= too close to px
- width of emergent beam at sighthole is too large- unable to view full image
- transverse movement of CL- misaligned=light not getting into pupil
Why is a panret 2.2 used?
- good mag w/o reducing FOV
- lower working dx
Why is scleral indentation used with BIO?
- dynamic view of retina
- far peripheral view of retina
- Close examination of lesions detected by other methods
- New symptoms of photopsia and/or floaters
- History of retinal detatchment
- Highly myopic patients where the risk of peripheral retinal tears is greater
What feature of the fundus marks the seperation of superior and inferior regions?
long ciliary nerve
What are vortex vein ampullae and why are they important?
- red octupus liek structures in the mid periphery
- lies on the equator of the globe
What is the ora serrata?
- periphery termination of the sensory retina
- appears more scalloped
Easiest method order of BIO?
- superior nasal
- superior temporal
How do you achieve a better superior view?
- put chair up
- kneel down
- look up
How do you achieve a better inferior view
- chair lower
- hold eyelid up
- lower head
How do you achieve better temporal or nasal views?
get px to look left or right
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