Ophthalmoscopy A clinical examination of the posterior segment by the means of an ophthalmoscope. It is primarily done to assess the state of fundus and detect the opacities of ocular media. Ophthalmoscope An instrument that allows the ophthalmologist to look inside a person’s eye and see the details of the living retina

1. INDIRECT OPHTHALMOSCOPY
Presenter- Shayri Pillai
Liberia Eye Centre
JFK Memorial Medical Centre
LV Prasad Eye Institute
LIBERIA
SEPTEMBER 10 2019

2. CONTENTS:
OPHTHALMOSCOPY
INTRODUCTION
HISTORY
TYPES
PREREQUISITES
PROCEDURE

3. SLIT LAMP BIOMICROSCOPY LENS
TYPES
VOLK DOUBLE ASPHERIC LENS
90 D LEN
PROCEDURE

4. INTRODUCTION

5. Ophthalmoscopy
 A clinical examination of the posterior segment by the
means of an ophthalmoscope.
 It is primarily done to assess the state of fundus and
detect the opacities of ocular media.
Ophthalmoscope
An instrument that allows the ophthalmologist to look
inside a person’s eye and see the details of the living
retina.

6. TECHNIQUES OF USED FOR FUNDUS EXAMINATION
Three methods of examination used in Ophthalmoscopy
are:
 Distant direct ophthalmoscopy
 Direct ophthalmoscopy
 Indirect ophthalmoscopy

7. Slit-lamp biomicroscopic examination of the fundus by:
 Indirect slit-lamp biomiscroscopy
 Hruby lens biomicroscopy
 Contact lens biomicroscopy

8. HISTORY
1848- Babbage invented ophthalmoscope
1850- Helmoltz direct ophthalmoscope
1852- Reute 1st mono ocular indirect ophthalmoscope
1864- Nagel indirect ophthalmoscope
1946- Charles Schepens modern binocular indirect
ophthalmoscope

9. TYPES
 Monocular Indirect Ophthalmoscope

10. OPTICS:
 An internal relay lens system re inverts the initially inverted
image to a real erect one, which is then magnified.
 This image is focusable using the focusing lever.

11. Parts of Monocular Indirect Ophthalmoscope

12. PARTS:
It consists of-
 Illumination rheostat at its base.
 Focusing lever for image refinement.
 Filter dial with red free and yellow filters.
 Forehead rest for proper observer head positioning.
 Iris diaphragm lever to adjust the illumination beam
diameter.

13. ADVANTAGE:
 Field of view similar to IO.
 Erect real image similar to DO.
DISADVANTAGE:
 Lack of stereopsis
 Limited illumination
 Fixed magnification.

14.  Binocular Indirect Ophthalmoscope

15. INTRODUCTION
The binocular indirect ophthalmoscope or indirect
ophthalmoscope, is an optical instrument worn on the
examiner’s head and sometimes attached to spectacles,
that is used to inspect the fundus or back of the eye.
It produces an stereoscopic image.

16.  Applicable to all refractive errors.
 Beam penetrates opacities in most media.
 There is a reduced image size.
 A wide view of the retina and its defects can be
obtained.

17. OPTICAL PRINCIPLE
 The principle of IO is to make the eye highly myopic by
placing a strong convex lens in front of patient’s eye so that
the emergent rays from an area of the fundus are brought
to focus as a real, inverted image between the lens and the
observer’s eye.
An aerial image is formed.

18. Fundus image formation
Skuta,G.L. et.al. AAO Clinical Optics 2016 Edition.USA chapter 7

19. An aerial image formation
Skuta,G.L. et.al. AAO Clinical Optics 2016 Edition.USA chapter-7

20.  In the indirect method of ophthalmoscopy a powerful
convex lens (called the condensing lens) is held in front
of the patient's eye. The usual powers used are +20 D
and +13 D.
 The illuminating light beam passes the condensing lens
into the eye and light reflected from the retina is
refracted by the condensing lens to form a real image
between the condensing lens and the observer.
 The observer studies this real image of the patient's
retina
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-174

21. Image formed by indirect ophthalmoscope
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-174

22. PREREQUISITES:
 Darkroom
 Source of light and concave mirror or self
illuminated indirect ophthalmoscope.
 Convex lens (now-a-days commonly employed
lens is of +20 D)
 Pupils of the patient should be dilated.

23. dIAGRAM
Parts of Indirect Ophthalmoscope

24.  Illumination is usually provided by an electric lamp
mounted on the observer's head.
 Light from this source is rendered convergent by the
condensing lens.
 A convergent beam enters the patient's eye and is
brought to a focus within the vitreous by the eye's
refractive system.
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-174

25.  The light then diverges to strike the retina.
 The illumination is therefore bright and even, as it
comes from the real image of the light source within
the patient's eye.
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-174

26. Indirect Ophthalmoscope- Field of Illumination
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-175

27.  The condensing lens is held in front of the patient's eye
at such a distance that the patient's pupil and the
observer's pupil are conjugate foci.
 Light arising from a point in the subject's pupillary plane
is brought to a focus by the condensing lens in the
observer's pupillary plane.
Conjugacy of pupil
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-175

28. Conjugacy of pupils
Skuta,G.L. et.al. AAO Clinical Optics 2016 Edition.USA chapter 7

29. A reduced image of the observer's pupil is formed in
the subject's pupillary plane (the image of a 4 mm pupil
is approximately 0.7 mm).
The observer's pupil is the 'sight-hole' of the system
and its size influences the field of view.
Construction of the reduced image
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-175

30.  The field of view is also limited by the aperture or size
of the condensing lens.
 Only those rays which leave the subject's eye via the
image of the observer's pupil and which then pass
through the condensing lens will be seen by the
observer.
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-175

31. Field view
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-176

32.  Light emerging from the patient's eye is refracted by the
condensing lens to form a real image of the retina
between the condensing lens and the observer.
 The image is both vertically and laterally inverted (upside
down and back to front).
 It is situated at or near the second principal focus of the
condensing lens, i.e. approximately 8 cm in front of a
+13 D lens .
Elkington A.R.et.al Clinical Optics 3rd EditionU.K. P-177
PROCEDURE

33.  The observer holds the condensing lens at arm's
length and thus views the image from a distance of
40–50 cm.
 To see the image clearly the observer must
accommodate or use a presbyopic correction.
 The binocular indirect opthalmoscopes have +2.0 D
lenses incorporated in the binocular prismatic
eyepieces so that the observer does not need to
accommodate.
Elkington A.R.et.al Clinical Optics 3rd Edition U.K. P-177

34.  Examiner stand opposite the clock hour position to be
examined, e.g., to examine inferior quadrant (around 6
O’clock meridian)or the examiner stands towards
patient’s head (12 O’clock meridian) and so on.
 By asking the patient to look in extreme gaze, and using
of scleral indenter, the whole peripheral retina up to ora
serrata can be examined.

35. Indirect Ophthalmoscopy

36.  A retinal indenter will both increase the peripheral view
and throw some retinal lesions into relief (for example,
retinal tears) so they are more easily seen.
 The patient is asked initially to look up or down to
facilitate placement of the indenter through the lower
or upper lid respectively.
Indentation

37.  The patient then looks towards the indenter and the
examiner gently presses on the indenter; a small
indentation should be seen in the peripheral retina.
 The indenter is gently moved round the eye, and
again the examiner needs to move around the patient
to maximise the view.

38. An indenter

39. Indirect Ophthalmoscope: Linear magnification
Elkington A.R.et.al Clinical Optics 3rd Edition U.K. P-178

40. Linear Magnification= ab/AB
Angle aCF = angle ANB because Ca and AN are parallel
Tan aCF= ab/CF =tan ANB =AB/BN
Therefore
ab/AB = CF/BN
CF is the focal length of the condensing lens. BN is the
distance between the nodal point and the retina of the
subject's eye.
Elkington A.R.et.al Clinical Optics 3rd Edition U.K. P-178

41. The exact values depend on the distance from which the
observer views the real image of the subject's retina, and
upon the distance between the condensing lens and the
subject's eye if this is ametropic .
Elkington A.R.et.al Clinical Optics 3rd Edition U.K. P-178

42. The refractive state of the patient's eye affects the size
and position of the real image formed by the condensing
lens.
Indirect ophthalmoscope. Relative positions of the image
Elkington A.R.et.al Clinical Optics 3rd Edition U.K. P-179

43.  All rays emerging from an emmetropic eye are parallel.
 Rays emerging from a hypermetropic eye are divergent,
and the real image is therefore formed outside the
second principal focus of the condensing lens.
 Emergent rays from a myopic eye are convergent, and
the real image is therefore always within the second
focal length of the lens.
Elkington A.R.et.al Clinical Optics 3rd Edition U.K. P-178

44. Elkington A.R.et.al Clinical Optics 3rd Edition U.K. P-174

45. Comparison of view within the same fundus using the indirect
ophthalmoscope and the direct ophthalmoscope in DR

46. Biomicroscopic examination of the fundus can be
performed after full mydriasis using a slit-lamp and any
one of the following lenses:
 Indirect slit-lamp biomicroscopy- +78 D, +90 D small
diameter lenses is presently the most commonly employed
technique for biomicroscopic examination of the fundus.
 Hruby lens biomicroscopy- Hruby lens is a
planoconcave lens with dioptric power 58.6D. This lens
provides a small field with low magnification and cannot
visualize the fundus beyond equator.

47.  Contant lens biomicroscopy can be performed by
following lenses:
Posterior fundus contact lens is a modified
Koeppe’lens.The image produced by it is virtual and erect.
 Goldmann’s three-mirror contact lens
consists central contact lens and three mirrors placed in
the cone, each with different angles of inclination .
With this the central as well as peripheral parts of the
fundus can be visualized.

48. A, +78D or +90D, small diameter lens. B, Hruby lens; C, Posterior
fundus contact lens (modified Koeppe’s lens); D, Goldmann’s three-
mirror contact lens.

49. VOLK DOUBLE ASPHERIC LENSES
HISTORY
 In 1956,aspheric ophthalmic lenses for subnormal vision
were developed by Dr. David Volk. He found that an
aspheric surface corrected the aberrations present in more
common spherical lenses.
 Several developments ocurred up to 1982 when all Volk
lens for indirect ophthalmoscopy were redesigned with both
surfaces aspheric, providing substantial improvement in
image quality.

50. INTRODUCTION
 Volk’s 60D,78D and 90d fundus lenses have establishes
slit lamp indirect ophthalmoscopy as comprehensive
fundus evalution.
 Examination of the retina by Slit lamp and Volk double
aspheric lenses is called a Bio microscopic Indirect
Ophthalmoscope BIO.

51. Characteristics
 Stereoscopic,3 dimensional view of the retina.
Binocular viewing through the slit lamp.
 Better image achieved when viewing through
media opacities like cataract.
 Allows for manipulation of the image.
Slit lamp magnification filters.
 Image size less affected by patient refractive error.

52. Slit-lamp-based indirect lenses
90 D lens
Used to carry out indirect ophthalmoscopy using the
slit lamp as a light source.
Gives more magnification than with a conventional
indirect ophthalmoscope, but may not give such ready
access to the retinal periphery.

53. It is a useful technique for the examination of the optic
disc posterior pole and relatively peripheral retina.
An advantage is that examination of the central fundus
can also take place with minimal or no dilation of the
pupil, although a more accurate examination is always
achieved with a dilated pupil.
Other commonly used non-contact lenses are variants
of the 90 D such as the 60 D, the superfield NC
(non-contact) and the 70 D lens.

54. Procedure
The slit beam is positioned vertically and centrally in
front of the patient’s pupil.
The short mirror should be in place.
The lens is held in parallel to the patient’s cornea and
close to it. The examiner’s fingers can be used to
support the eyelids.
The slit beam thus passes through the lens and pupil
to the retina.

55. The slit lamp is then slowly drawn backwards and
towards the examiner whilst the examiner maintains
a view through the binocular eyepieces until the
inverted retinal image comes into focus.
The slit beam is manipulated to vary the area of
retina being illuminated and the patient asked to look
in the relevant direction to view different areas of the
retina.

56. The lens is tilted to look at various parts of the
peripheral fundus .
Adjustment to the focus also allows the vitreous to be
seen.
The system of examination is similar to that outlined for
the direct ophthalmoscope.

57. Examination with 90 D lens

58. PITFALLS
The image obtained at the slit lamp through these
lenses is upside down and laterally inverted.

59. Indications
Useful method of examination for patients in a general
clinic to obtain a view of the fundus, even when the
pupil is not dilated.
Gives a reasonably magnified image and a good field
of view.
The optic disc is well seen and the stereoscopic view
is useful in analysing the neuroretinal rim.
It is also a useful method for delivering laser energy to
the fundus, for it does not disturb the corneal surface,
giving a clear image.

60. Thank you!
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L V Prasad Eye Institute