BIO Flashcards
What does placing the lens in front of the eye cause the image to do in BIO
Makes the eye highly myopic
A real, inverted, and laterally inverted image is formed in front of the lens
Where is the image formed in BIO
Close to the principle focus of the lens, between the lens and the observer
What is the first thing you do in BIO
Explain procedures and wash your hands
What is the advantage of using a higher powered condensing lens in BIO
Higher power lenses offer greater FOV and can aid with examination through small pupils
What does the power of the condensing lens determine
Working distance
Magnification
FOV
What happens to working distance, mag, and FOV when the power of the condensing lens decreases
FOV decreases
working distance and mag increase
+30 magnification
2x
+30 FOV
60 deg
Stereopsis of a +30 lens
1/2
Working distance from cornea with a +30
26mm
Mag of 20+
3.25X
FOV of +20
40 deg
Stereopsis with a +20
3/4
Working distance of +20
47mm
Mag of a +14/15 lens
4.17x
FOV of a +14/15 lens
30 deg
Stereopsis of a +14/15 lens
1
Working distance from cornea with a +14/15 lens
72mm
Used to obtain a panoramic view when detail and stereopsis are not as important, and used with small pupil
30D
Which condensing lens has the shortest working distance
+30
Most widely used condensing lens since it provides an adequate FOV, stereopsis and magnification
20D
Most useful for detailed view of the macula or optic disc or for determining elevation of the retina in shallow retinal detachment
15D
What is the room lighting that is best for BIO
Dark enough to achieve sufficient contrast, avoid too much ambient light
What light should you begin with in BIO
Not the brightest one. Once the patient is accustomed to the light, you can gradually turn it up to double check a selected area
