Indirect ophthalmoscopy

Question 1

Compare the magnification and FOV of indirect and direct opthalmoscopy?

Answer 1

Indirect ophthalmoscopy:
magnification= x2 - x5
FOV= 25º - 45º

Direct opthalmoscopy:
mag= x15
FOV= 10º (2 disc diameters)

Question 2

state all 6 factor affecting indirect ophthalmoscopy?

Answer 2

1- distance between the patient and lens
2- distance between the observer and lens
3- pupil size
4- Ammetropia
5-lens power
6- diameter of condensing lens

Question 3

state two monocular indirect ophthalmoscopy techniques used?

Answer 3

pan optic

keeler

Question 4

Monocular indirect ophthalmoscopy produces what kind of an image?

Answer 4

real and erect and no stereopsis

Question 5

what is the FOV , WD and mag in monocular indirect ophthalmoscopy?

Answer 5

FOV = 15º

lower mag= x5

Question 6

True or false:

a special condensing lens is not required for Monocular indirect Op.

Answer 6

true

Question 7

describe the procedure of Pan Optic technique (include FOV and WD )

Answer 7

• monocular
• Greater FOV than Direct Op.
• Greater WD
• Same as direct Op, bring eyecup into contact with patient, compress eyecup halfway to achieve maximum view.

Question 8

what is the field of view using the Keeler Wide angle device ?

Answer 8

FOV is x10 larger

Question 9

What is an aerial image and how is it produced and by what technique?

Answer 9

• Binocular indirect Op. produces an aerial image between the patient and examiner.
• Light from illumination system is reflected off the retina and converged by a condensing lens to produce an aerial image

Question 10

Describe the image produced by Binocular indirect Op.

Answer 10

Real, magnified, inverted and laterally reversed aerial image.

Question 11

what is the range of the condensing power lens used during binocular indirect Op.

Answer 11

+14D to +90D

Question 12

What is the general rule involving power, mag, lens diameter and FOV?

Answer 12

the higher the power, the lower the mag, the lower the lens diameter and greater the FOV.

Question 13

where is the optic disc positioned relative to the macula?

Answer 13

optic disc is nasal.

Macula is always temporal (towards ears)

Question 14

State the mag, FOV, power of condensing lens, image and procedure of the binocular indirect headset technique in indirect Op.

Answer 14

• x2.5 Magnification (depends on lens)
• 30º FOV
• Power of condensing lens varies from +30D to +14D, +20D is most common
• Image is real, inverted, laterally reversed and stereoscopic view.
• Procedure: Set up headband, accounting pupil size and refractive error. Hold condensing infant of patients’ eye and pull lens back until fundus image fills in. There are 8 positions and remember inversion.

Question 15

when should we use the binocular indirect headset?

Answer 15

• poor direct view with direct ophthalmoscope.
• for a stereoscopic view
• To see whole fundus- diabetics, young children

Question 16

Which equipment underpins indirect biomicroscopy?

Answer 16

Volk lenses

Question 17

State the WD, FOV, mag and power and lens type used in indirect biomicroscopy?

Answer 17

WD= short
power= +90D and +78D 
Lens type= bi-convex lens of above powers
FOV= smaller than 30º (depends on power)
mag= less mag with stronger lenses

Question 18

when should a Volk lens be used?

Answer 18

• when you have a poor direct view (opacity/ Rx / pupil size)
• you require a stereoscopic view
• a wider FOV than direct.

Question 19

What is direct biomicroscopy?

Answer 19

a slit lamp

Question 20

State the FOV, Power, Lens type, image and procedure used when a slit lamp is used?

Answer 20

• FOV= smaller than Volk- less than 30º
• Power= -55D
• Lens type= Hruby plano concave (concave side towards patient)
• Image is not inverted- binocular erect image
• Procedure= you must neutralise corneal power using a high power negative lens or contact lens , and have a direct view os fundus with slit lamp.

Question 21

Contact lenses are ________-________. A viscous ____ is used between eye and ____, this is anaesthesia.

Answer 21

corneo- scleral
gel
lens

Question 22

Fundus camera is a specialised ____ power microscope with an attached ______. It has ____ ______ sources.
One to view______ and /or adjust _____ and one to take a flash _______.

Answer 22

low
camera
two 
light
fundus
focus
photo

Question 23

A scanning laser ophthalmoscope uses a _____ light to take images of _______ of the retina. The images are ______ along x, y and z axes. A ______ light is used with a high _______ to produce a monochromatic image. It is used for imaging nerve head in ________.

Answer 23

laser
slices
confocal
lower
magnification
glaucoma