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Direct & Indirect
Ophthalmoscope
Mahendrda Singh
PhD (Scholar)
Assistant Professor and Consultant Optometrist
CL Gupta Eye institute, Moradabad UP India
• Objective method of examining the posterior
segment of the eye.
• Presence or absence of abnormalities in the
posterior segment - structural or pathological.
• View of vascular & neurological structures of a living
organ in-situ.
Introduction
Types
• Can be divided into two types :
– Direct ophthalmoscope
– Indirect ophthalmoscope
Direct
Ophthalmoscope
History
1846- Charles Babbage, constructed
first ophthalmoscope.
1850’s- Von Helmholtz - Father of
ophthalmoscope.
PRINCIPLE
• Work on the principle of ANGULAR
Magnification.
Optics
• A convergent beam of
light is reflected into
the patient’s pupil.
• The emergent rays
from any point on the
patient’s fundus reach
the observer’s retina
through the viewing
hole in the
ophthalmoscope.
Optics (In Hyperopic patient’s)
• In a hypermetropic
patient’s, the emergent
ray from the illuminated
area of retina will be
divergent & thus can be
brought to focus on the
observer’s retina if the
latter accommodates,
or by the help of a
convex lens
Optics (In Myopic patient’s)
• In a myopic patient’s
the emergent rays will
be convergent & thus
can be brought to
focus on the observer
retina by the help of a
minus lens
Instrumentation
• Illuminating system
• viewing system
Illuminating system
• Illuminating system consists of:
- Tungsten bulb
- Condenser system
- Lens
- Reflector (half silvered mirror)
- Aperture stops and filters (between condensing
lens and projection lens)
Illuminating system
• Filters
- Red-free filter (green)
- Blue filter
Green filter
• Increases the contrast between retinal vessels and the
background
• To differentiate between retinal and choroidal lesions.
Illuminating system
• Nerve fibre layer of the retina.
• Early dropout of the nerve fibre layer.
• Enhance the estimation of CD ratio.
Blue filter
• Enhances the visibility of fluorescein for use in FFA.
viewing system
–Sight hole
–Focusing system
• Rack of lenses of different powers in the form
of a wheel or chain & accessory filters.
Lens track
chain
Eyebrow rest
Sight hole
viewing system
• It consists of 3 aperture stops :
1) Small - for macula
2) Intermediate - for viewing the fundus through
normal pupils
3) A large - to view through dilated fundus.
viewing system
• Slit diaphragm - observing elevated retinal
lesions.
• Half circle - reduces reflection by limiting the
illumination & observing certain fine retinal
details.
• Fixation star - to determine patients fixation in
strabismic amblyopia.
Half circle
Small aperture
Intermediate aperture
Fixation star
Slit aperture
Filter changing lever
Green filter
Large aperture
Sight hole
Blue filter
Aperture stop
Characteristics of image formed
• In direct
ophthalmoscope the
image is ERECT,
VIRTUAL, & about 15
times MAGNIFIED
• Field of view is 5*
from the fixn. point
Magnification
Depend on angular magnification,
Therefore A M is achieved by
AM=POWER OF THE EYE/4
M=60/4
=15X.
Field of vision
• Directly proportional to the size of the pupil of
observed eye
• Directly proportional to the axial length of the
observer’s eye
• Inversely proportional to the distance between the
observer’s & observed eye
• The smaller the sight hole of ophthalmoscope the
better the field of vision
Technique
• Patient seated in semi-dark room & looking straight
ahead
• Pt. right eye should be examined by the observer
with his right eye & left with the left
• Once the red reflex is seen, the observer should
move as close to the patient’s eye as possible
(theoretically at the antr. focal plane of the pt. eye
i.e. 15.4mm)
Clinical uses
• The homogeneity of cornea & lens may also
checked,
• Irregularities in the optical structures as black
shadow.
• Small hemorrhages or aneurysms, which can
easily locate.
• Used as distant direct ophthalmoscope.
• Used as BRUCKNER reflex test.
Advantages
• Magnification is about 15 x.
• Easier to use with small and undilated pupil.
• Easier mechanically.
• Portable.
Disadvantages
• Field of view is smaller
• Peripheral view of retina is not possible.
• It is not easy in viewing the fundus in cloudy
media.
• Stereopsis is not present.
• Limited Illumination.
Indirect
Ophthalmoscope
Introduction
• Introduced by Nagel in 1864
• Very popular method for examination of the
posterior segment
TYPES
• BINOCULAR INDIRECT OPHTHALMOSCOPE
• MONOCULAR INDIRECT OPHTHALMOSCOPE
Indirect Ophthalmoscope
1. Aperture lever
2. Teaching mirror
3. Convergence
control
4. Filter lever
11. Control for
vertical illumination
A. Press knob
B. Adjuster for over
band
Parts
Parts
5. Unscrew
knob
6. Control for
over band
7.Circumferen
ce adjuster
8.Height
adjuster
9.Over band
10.optics.
Parts
12.Brightness selection
13.Bulb connector
14.Bulb
15.Locating pin
16.Slit
17.Fibre optics cable
18.Cord socket
Accessories used
• 1.Condensing Lens
• 2.Indenter
Principle of I.O
The principle of I.O is to
make the eye highly myopic
by placing a strong convex
lens in front of Pt. eye so that
the emergent rays from an
area of the fundus are
brought to focus as a real
inverted image between the
lens & the observer eye,
which is then studied
Optical system of I.O
• Binocularity is
achieved by reducing
the observer I.P.D to
approx. 15mm by
prisms/mirror.
FIRST ATTEMPT AT BINOCULAR VIEW
Obs. L eye
Obs. R eye
S’s eye
Combine L and R eye views
Observer’s eyes have to be too close
IMAGE ORIENTATION
MAGNIFICATION
FIELD OF VIEW
Characteristics of image
IMAGE ORIENTATION
The emergent rays from
the illuminated area of
retina are parallel in
emmetropic Pt. & are
therefore brought to focus
by the condensing lens at
its principal focus, thus an
inverted image of the
retina is formed in the air
between the condensing
lens & the observer.
Image formed
• Arial image
• Real, inverted, magnified
MAGNIFICATION
20 D
lens
RI
60 D
eye
OPHTHALMOSCOPE MAGNIFICATION
Peye
Plens
=
60 D
20 D
= 3.0
M =
FIELD OF VIEW
20 D
40
Area of binocular view
BINOCULAR FIELD OF VIEW
GTT 04
Advantages
• Large field of view.
• Easy to view the extreme periphery.
• Easy to view in cloudy media
• Use of indenter becomes easy.
• Good illumination.
• Hand free for operative purpose.
Disadvantages
• Low magnification.
• It cannot be well perform in undilated pupil.
• Mechanically not easy.
• Not portable.
Monocular I O
Its virtue is to permits visualisation of the
fundus through an undilated pupil and the
image seen is errect rather than inverted and
sterioscopic visualisation is not possible.
Few difficulties to deal with
• Unwanted reflections of light which comes
from the anterior and posterior surface of the
convex lens and the patients cornea.
• In case of small pupil.
• In case of large pupils.
Comparison
Feature Direct Indirect (20 D)
Magnification 15x 3 x
Field diameter 2 DD 9 DD
Illumination Limited High
Depth of focus Small Large
Stereopsis Absent Present
Image
Orientation Upright reversed
Periphery view Limited Full
Working distance Close Arm’s length
Scleral indentation Difficult Easy
Colour Code for Fundus Chart
Color Code for Fundus Chart
Red
Attached retina
Arteries
Retinal breaks
Thin retina
Retinal hemorrhages (superficial
& deep)
Microaneurysms
Retinal new vessels (flat &
elevated)
Color Code for Fundus Chart
Blue
Detached retina
Retinoschisis
Veins
Outline of retinal breaks
Lattice degeneration
BROWN
CHOROIDAL DETACHMENT
Color Code for Fundus Chart
Yellow
Exudates, Drusen
Green
Media Opacities
(label specific lesion)
Black
Retino-choroidal pigmentation
Ora serrata
• Thank you

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Direct & Indirect Ophthalmoloscope.pdf

  • 1. Direct & Indirect Ophthalmoscope Mahendrda Singh PhD (Scholar) Assistant Professor and Consultant Optometrist CL Gupta Eye institute, Moradabad UP India
  • 2. • Objective method of examining the posterior segment of the eye. • Presence or absence of abnormalities in the posterior segment - structural or pathological. • View of vascular & neurological structures of a living organ in-situ. Introduction
  • 3. Types • Can be divided into two types : – Direct ophthalmoscope – Indirect ophthalmoscope
  • 5. History 1846- Charles Babbage, constructed first ophthalmoscope. 1850’s- Von Helmholtz - Father of ophthalmoscope.
  • 6. PRINCIPLE • Work on the principle of ANGULAR Magnification.
  • 7. Optics • A convergent beam of light is reflected into the patient’s pupil. • The emergent rays from any point on the patient’s fundus reach the observer’s retina through the viewing hole in the ophthalmoscope.
  • 8. Optics (In Hyperopic patient’s) • In a hypermetropic patient’s, the emergent ray from the illuminated area of retina will be divergent & thus can be brought to focus on the observer’s retina if the latter accommodates, or by the help of a convex lens
  • 9. Optics (In Myopic patient’s) • In a myopic patient’s the emergent rays will be convergent & thus can be brought to focus on the observer retina by the help of a minus lens
  • 11. Illuminating system • Illuminating system consists of: - Tungsten bulb - Condenser system - Lens - Reflector (half silvered mirror) - Aperture stops and filters (between condensing lens and projection lens)
  • 12. Illuminating system • Filters - Red-free filter (green) - Blue filter Green filter • Increases the contrast between retinal vessels and the background • To differentiate between retinal and choroidal lesions.
  • 13. Illuminating system • Nerve fibre layer of the retina. • Early dropout of the nerve fibre layer. • Enhance the estimation of CD ratio. Blue filter • Enhances the visibility of fluorescein for use in FFA.
  • 14. viewing system –Sight hole –Focusing system • Rack of lenses of different powers in the form of a wheel or chain & accessory filters.
  • 16. viewing system • It consists of 3 aperture stops : 1) Small - for macula 2) Intermediate - for viewing the fundus through normal pupils 3) A large - to view through dilated fundus.
  • 17. viewing system • Slit diaphragm - observing elevated retinal lesions. • Half circle - reduces reflection by limiting the illumination & observing certain fine retinal details. • Fixation star - to determine patients fixation in strabismic amblyopia.
  • 18. Half circle Small aperture Intermediate aperture Fixation star Slit aperture Filter changing lever Green filter Large aperture Sight hole Blue filter Aperture stop
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  • 20. Characteristics of image formed • In direct ophthalmoscope the image is ERECT, VIRTUAL, & about 15 times MAGNIFIED • Field of view is 5* from the fixn. point
  • 21. Magnification Depend on angular magnification, Therefore A M is achieved by AM=POWER OF THE EYE/4 M=60/4 =15X.
  • 22. Field of vision • Directly proportional to the size of the pupil of observed eye • Directly proportional to the axial length of the observer’s eye • Inversely proportional to the distance between the observer’s & observed eye • The smaller the sight hole of ophthalmoscope the better the field of vision
  • 23. Technique • Patient seated in semi-dark room & looking straight ahead • Pt. right eye should be examined by the observer with his right eye & left with the left • Once the red reflex is seen, the observer should move as close to the patient’s eye as possible (theoretically at the antr. focal plane of the pt. eye i.e. 15.4mm)
  • 24. Clinical uses • The homogeneity of cornea & lens may also checked, • Irregularities in the optical structures as black shadow. • Small hemorrhages or aneurysms, which can easily locate. • Used as distant direct ophthalmoscope. • Used as BRUCKNER reflex test.
  • 25. Advantages • Magnification is about 15 x. • Easier to use with small and undilated pupil. • Easier mechanically. • Portable.
  • 26. Disadvantages • Field of view is smaller • Peripheral view of retina is not possible. • It is not easy in viewing the fundus in cloudy media. • Stereopsis is not present. • Limited Illumination.
  • 28. Introduction • Introduced by Nagel in 1864 • Very popular method for examination of the posterior segment
  • 29. TYPES • BINOCULAR INDIRECT OPHTHALMOSCOPE • MONOCULAR INDIRECT OPHTHALMOSCOPE
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  • 35. 1. Aperture lever 2. Teaching mirror 3. Convergence control 4. Filter lever 11. Control for vertical illumination A. Press knob B. Adjuster for over band Parts
  • 36. Parts 5. Unscrew knob 6. Control for over band 7.Circumferen ce adjuster 8.Height adjuster 9.Over band 10.optics.
  • 37. Parts 12.Brightness selection 13.Bulb connector 14.Bulb 15.Locating pin 16.Slit 17.Fibre optics cable 18.Cord socket
  • 38. Accessories used • 1.Condensing Lens • 2.Indenter
  • 39. Principle of I.O The principle of I.O is to make the eye highly myopic by placing a strong convex lens in front of Pt. eye so that the emergent rays from an area of the fundus are brought to focus as a real inverted image between the lens & the observer eye, which is then studied
  • 40. Optical system of I.O • Binocularity is achieved by reducing the observer I.P.D to approx. 15mm by prisms/mirror.
  • 41. FIRST ATTEMPT AT BINOCULAR VIEW Obs. L eye Obs. R eye S’s eye Combine L and R eye views Observer’s eyes have to be too close
  • 42. IMAGE ORIENTATION MAGNIFICATION FIELD OF VIEW Characteristics of image
  • 43. IMAGE ORIENTATION The emergent rays from the illuminated area of retina are parallel in emmetropic Pt. & are therefore brought to focus by the condensing lens at its principal focus, thus an inverted image of the retina is formed in the air between the condensing lens & the observer.
  • 44. Image formed • Arial image • Real, inverted, magnified
  • 45. MAGNIFICATION 20 D lens RI 60 D eye OPHTHALMOSCOPE MAGNIFICATION Peye Plens = 60 D 20 D = 3.0 M =
  • 46. FIELD OF VIEW 20 D 40 Area of binocular view BINOCULAR FIELD OF VIEW GTT 04
  • 47. Advantages • Large field of view. • Easy to view the extreme periphery. • Easy to view in cloudy media • Use of indenter becomes easy. • Good illumination. • Hand free for operative purpose.
  • 48. Disadvantages • Low magnification. • It cannot be well perform in undilated pupil. • Mechanically not easy. • Not portable.
  • 49. Monocular I O Its virtue is to permits visualisation of the fundus through an undilated pupil and the image seen is errect rather than inverted and sterioscopic visualisation is not possible.
  • 50. Few difficulties to deal with • Unwanted reflections of light which comes from the anterior and posterior surface of the convex lens and the patients cornea. • In case of small pupil. • In case of large pupils.
  • 51. Comparison Feature Direct Indirect (20 D) Magnification 15x 3 x Field diameter 2 DD 9 DD Illumination Limited High Depth of focus Small Large Stereopsis Absent Present Image Orientation Upright reversed Periphery view Limited Full Working distance Close Arm’s length Scleral indentation Difficult Easy
  • 52. Colour Code for Fundus Chart
  • 53. Color Code for Fundus Chart Red Attached retina Arteries Retinal breaks Thin retina Retinal hemorrhages (superficial & deep) Microaneurysms Retinal new vessels (flat & elevated)
  • 54. Color Code for Fundus Chart Blue Detached retina Retinoschisis Veins Outline of retinal breaks Lattice degeneration BROWN CHOROIDAL DETACHMENT
  • 55. Color Code for Fundus Chart Yellow Exudates, Drusen Green Media Opacities (label specific lesion) Black Retino-choroidal pigmentation Ora serrata