Indirect Ophthalmoscopy and Optos

Question 1

image from direct ophthalmoscopy is:

Answer 1

virtual, erect, non reversed

Question 2

limiting factors to direct ophthalmoscopy are:

Answer 2

• pupil size of patient
• distance to observer
• refractive error
• limited FOV

Question 3

which is better for getting through very small pupils: DO or BIO?

Answer 3

DO

Question 4

in DO, high myopia results in _____ field of view

Answer 4

decreased FOV

b/c greater mag

Question 5

in DO, high hyperopia results in ____ field of view

Answer 5

increased FOV

Question 6

FOV in DO is about ____-____ degrees in an emmetrope

Answer 6

10 to 15 degrees

Question 7

FOV is BIO is about ___ degrees

Answer 7

30

Question 8

in BIO, the image is:

Answer 8

real, inverted, reversed, aerial, and 3D

Question 9

where is the image located in BIO?

Answer 9

between the patient and the examiner

Question 10

main advantages of BIO:

Answer 10

• binocular view (resolution and depth perception)
• high illumination (better resolution)
• low mag
• large FOV

Question 11

failure to do what will result in the view in the lens not “filled” from edge to edge?

Answer 11

failure to hold the lens at its focal point from the patient’s eye

Question 12

for a 20D condensing lens: the image is about ___cm from the lens

Answer 12

5cm

Question 13

closer viewing distances in BIO require:

Answer 13

• greater accommodation
• greater convergence
• much more precise alignment of all components

Question 14

since it is very difficult to maintain a binocular, well-focused, well-illuminated image at closer distances, it is best to stay about ___-__cm from the lens

Answer 14

25 to 30cm

Question 15

how does the viewing triangle get imaged into the patient’s pupil?

Answer 15

• mirrors in the BIO headset optically shrink the examiner’s PD to ~15-20mm
• condensing lens magnifies the patient’s pupil

Question 16

clinical keys for small pupil

Answer 16

• switch to small pupil setting to shrink viewing triangle

- higher power condensing lens (magnifies pt’s pupil more)

Question 17

BIO total mag=

Answer 17

[instrument mag] x [relative distance mag]

Question 18

instrument mag=

Answer 18

[power of eye] / [power of lens]

Question 19

relative distance mag=

Answer 19

[std viewing dist (25cm)] / [actual viewing distance]

Question 20

BIO: factors affecting magnification are:

Answer 20

• patient refractive error
• power of the condensing lens
• examiner to lens distance

Question 21

in BIO: decreased field of view can be caused by:

Answer 21

• lower power lens
• smaller diameter lens
• high myopia
• closer to patient
• pupil size (if small enough)

Question 22

procedures to perform before dilation

Answer 22

case history, best corrected VAs, pupils, anterior set (SLE), angles, tonometry

Question 23

major zones of the retina are

Answer 23

• central fundus (posterior pole and mid-periphery)

- peripheral fundus (equitorial region and oral region)

Question 24

what is the arbitrary definition for central fundus

Answer 24

that portion of the funds posterior to posterior edges of vortex veins

Question 25

what is used as the demarcation between the central and peripheral funds?

Answer 25

imaginary circle connecting the posterior edges of the vortex vein ampullae

Question 26

posterior pole region is defined as

Answer 26

ill defined region in most central fundus that includes ONH, macula, vascular arcades

Question 27

mid-periphery region is defined as

Answer 27

region just posterior to an imaginary circle connecting the posterior edges of the VV ampullae and anterior to the posterior pole

Question 28

what are the major funds landmarks in recognizing the retinal periphery?

Answer 28

VV ampullae

Question 29

equitorial region is defined as

Answer 29

4dd width extending anteriorly from an imaginary circle connecting posterior edges of VV ampullae