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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?
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?
How do you achieve a better superior view?
put chair up
How do you achieve a better inferior view
hold eyelid up
How do you achieve better temporal or nasal views?
get px to look left or right