Basics od fundus examination

1. Indirect Ophthalmoscopy and Slit
Lamp Biomicroscopy
By Dr.Lakshmi.K.S
Moderator: Dr.Sudhir Hegde

2. Index
 Indirect Ophthalmoscopy
• History
• Principle, procedure and recording of findings in IDO
• Small pupil IDO
• Scleral indentation technique
• Advantages and disadvantages
 Slit Lamp Biomicroscopy
• Types of lenses used, their advantages and
disadvantages
 Ophthalmologists health issues
 Fundus Drawing

3. History of Indirect Ophthalmoscope
• In 1700s- doddel, Richter, Beer noted
spontaneous luminosity of human eye
• 1823- Purkinje, under certain conditions of
illumination human eyes could be made luminous
• 1846, 1847- Cumming and Brucke finally realized
that the observer had to stand in the path of the
emerging rays to see the luminous eye
• 1850- helmoltz direct ophthalmoscope
• 1852- Reute 1st mono ocular indirect
ophthalmoscope

4. • 1958- schepens, binocular indirect
ophthalmoscope provides an excellent resolution
of fundus

5. Principle
• Indirect Ophthalmoscopy (IDO) involves making the eye
highly myopic by placing a high power convex lens (+13D to
+30D) in front of the eye so that a real, inverted and
laterally reversed image is formed in front of lens
• The technique is called Indirect because the fundus is seen
through a condensing lens.
• The image is formed close to the principle focus of the lens,
between the lens and the observer

6. Illumination System
• Presence of the corneal reflection and the
usual backscattered light of the healthy
cornea and lens make the evaluation of
fundus changes difficult.
• Gullstrand evaluated the principles
• Observation beam and the illumination
beam be separated at the corneal and lens
plane, to avoid corneal and lens reflection
and scatter for which a dilated pupil is
needed
• With patient and observer pupils conjugate,
loss of light is minimized, and field of view is
maximized.

7. The power of the condensing lens determines:
• Working distance
• Magnification
• Field of view
 As the power of condensing lens decreases, field of view
decreases but working distance and magnification increases
 Roughly, magnification is the eye power divided by the power of
condenser lens used
Lens Power
(D)
Static Field of View* Magnification Working Distance
from Cornea
+14 22 4.17 72 mm
+20 30 3.25 47 mm
+30 40 1.97 26mm

8. Stereopsis
• Normal interpupillary distance is about 60mm
• Reduced to 15mm by the use of prisms in IDO
• reduces the stereopsis appreciated by an observer by about
one fourth
• axial magnification (which equals one fourth of the square of
lateral magnification) augments the stereoscopic appearance

9. Parts of an indirect ophthalmoscope

10. Examination technique
Preparation:
• Dilatation of eyes.
•dark rooms preferred whenever possible.
• preferable to have a patient chair that fully reclines,
enabling the practitioner to move around the patient and
hence gaining a full 360° traverse of the fundus.
• If a reclining chair is not available, the practitioner will
have to make more use of the patient fixating peripheral
targets, and this will often mean that a smooth traverse
of the peripheral fundus is not possible

11. • Proprioception helps
patient to look in
cardinal gazes
• Patient should be
urged to keep the
other eye open
Helpful hints

12. Alignment of the head-band
ophthalmoscope
• Place the ophthalmoscope on the head and adjust the
straps for maximum comfort
• Face a wall approximately 40 cms away, and adjust the
illumination mirror such that the illumination field is
vertically centralized to the observation ports
• Move the viewing ports horizontally by adjusting the
interpupillary distance to align with the illumination
field
• Adjust the illumination system to give the required
field.
• Set the illumination at a medium intensity to start with.
Use the yellow lens to reduce the amount of blue light
on the retina

13. Procedure Proper
• The practitioner should first illuminate the patient’s pupil area by
pointing the head and hence the illumination towards the patient’s
eye.
• Interpose the condenser lens close to the eye about 2 cm, and centre
the lens on to the pupil. The lens should be held with the more convex
side towards the practitioner.
• Pull back the lens away from the patient’s eye, at the same time
taking care to keep the illumination centered on the pupil. Whilst
withdrawing the lens, the practitioner will find a distance that provides
an optimum field of view. This should be approximately at the focus of
the lens, i.e. 5cms from the pupil using a +20D lens
• Having obtained an image filling the BIO lens, the fundus may then
be examined by moving around the patient if reclining, or by
redirecting the patient’s fixation if seated

14. Holding the lens
Pivot

15. Imaginary Convex
Eye Technique
• One of the main difficulties
encountered by those new to
indirect ophthalmoscopy is that the
image of the fundus is both
inverted and reversed
• With direct ophthalmoscopy in
mind, the examiner would have
been tempted to move down or
ask the patient to look up
• The opposite is required with
indirect ophthalmoscopy and this
does take some getting used to.
• Whilst observing the aerial image
of the fundus, the practitioner
should imagine that the fundus
image is convex and not its true
concave form
In figure a naevus has
been observed by the
examiner(position P) on
the inferior fundus (seen
superiorly). The
optometrist should move
up (position S) or ask the
patient to look down to
view the lesion

16. Recording the findings
• By orienting the paper so that
its 12 o'clock meridian is
directed inferiorly toward the
patient's feet, the image
fields can be visually
translated directly onto the
paper without having to
mentally invert them.

17. Video

18. Small pupil indirect ophthalmoscopes
• Many IDO’s incorporate a small pupil feature
which facilitates the examination of eyes
when the pupils dilate poorly or eyes harbor
focal medial opacities
• A small lever located under the eye pieces is
moves in position to engage this feature
• This lever physically places the illumination
and visualization pathways closer together by
moving a triangular prism

19. Scleral depression
technique
• To take full advantage of head-
band binocular indirect
ophthalmoscopy, the practitioner
should learn to perform scleral
indentation
• Scleral indentation will neither
cause nor worsen retinal tears or
detachments
• The examiner should choose a
thimble or other type of depressor
tool that feels comfortable to hold
• Sitting to one side of the patient,
the examiner should gently place
the probe on the outside of the lid.
A starting position would be a little
higher than the inner canthus, just
missing the caruncle, and at 180°
to the observation angle

20. • The practitioner should very gently and tangentially move the
probe into the fold of the lid (approx 8mm from the limbus)
• Look for the indentation in the lower field of the BIO lens, as it
will be inverted. Keep the depressor moving slightly to aid
finding the indented retina
• The 3o/c and 9o/c positions can be indented by placing the
depressor slightly above on the upper lid (2o/c and 10o/c),
and sliding the probe round to move it into the inner or outer
canthal positions
• If this is difficult, indentation can be done applying the probe
to the sclera without the intervening lid, but topical
anesthesia should be used to make your patient comfortable

21. • A – Patient looks down, depressor on margin of sup tarsal
plate
• B – Depressor advanced into the orbit as patient looks up but
no depression applied as yet
• C – Scleral depression applied gently to area of interest
Scleral Depression technique

22. Critical in obtaining a binocular (stereoscopic) view

23. Comparison with direct
ophthalmoscopy

24. Advantages of IDO
• Larger field of view
• Lesser distortion of retinal image
• Easier to examine if patients eye movements are
present and with high spherical or astigmatic refractive
errors
• Stereopsis
• Useful in hazy media due to its bright light and optical
property
• Can be used intraoperatively
• Vitreous can be examined easily and various vitreous
abnormalities diagnosed through this

25. Disadvantages of IDO
• Difficult to learn
• Less magnification, therefore details of a small
lesion not visualized properly
• Impossible with very small pupils
• More uncomfortable to the patient

26. Inexpensive method of indirect
ophthalmoscopy
• K R Bishai- BJO 1989

27. Video indirect ophthalmoscopy
• Mahesh P shanmugam- IJO 2011

28. Simple model for indirect
ophthalmoscopy
Tumaini University/ KCMC, Moshi, Tanzania
- BJO 2006
Using
• Styrofoam pad
• Glass marble
• Small print paper
• Black paper

29. Slit Lamp Biomicroscopy
• Retinal SLM BIO affords high magnification and illumination
necessary to evaluate retinal lesions in detail
• Because the cornea has such a high refractive power, the slit-lamp
microscope can view only the first one third of the eye.
• Special lenses, in conjunction with the slit-lamp microscope, can be
used to view the posterior vitreous and the posterior pole retina.
• The two ways to overcome the high corneal refractive power are:
(1) nullify the corneal power
(2) utilize the power of the cornea as a component of an astronomical
telescope, in a manner similar to that exploited by the indirect
ophthalmoscope.

30. It consists of
• A binocular slit lamp biomicroscope
• Any one of the following lenses
1. Hruby lens
2. Contact lens biomicroscopy- modified koeppe’s
lens, wide field panfundoscopic indirect contact
lens, goldmann’s 3 mirror contact lens
3. Findus non contact lens- range from +60 to +132
D, most commonly 90D and 78D

31. Hruby lens biomicroscopy
• A plano concave non –contact
lens
• High minus power [-58.6 D]-
nullifies corneal power
• Virtual erect image
• To visualize
 optic cupping , peri papillary
changes
 Nerve fibre layer-thickness [red
free filter]
 Macular lesion level [slit beam
sideways movement-watzke
Allen test]
 Vitreous opacities, strands.
• Disadvantage- its used exclusively
for posterior pole as distortion
seriously degrades the image if
the fundus is viewed along any
axis other than the approximate
optical axis of the patient's eye

32. Contact lens biomicroscopy
• Goldman’s Contact lens
• Goldman’s three mirror contact lens
• Mainster contact lens
• Panfundoscopic contact lens

33. Contact lens biomicroscopy
• The Goldmann contact lens
-nullify the dioptric power
produced by the corneal
curvature and to bring the
retina into the focal range
of the slit-lamp microscope
• plano-concave contact
lenses
• forms virtual, erect, and
diminished images of the
illuminated retina near the
pupillary plane, within the
focal range of the slit-lamp
microscope.

34. Contact lens biomicroscopy-
Goldman’s 3 mirror lens
• Concavo plano contact lens -
virtual , erect image
• Combines stereopsis, high
illumination, high magnification
[10 x] , 20 degree field.
• Flat central portion – posterior
vitreous and pole
• Angled mirror-3
 73 deg - area around posterior
pole
 67 deg - equatorial fundus
 59 deg - peripheral retina and
iridocorneal angle
• Eliminates total internal
reflection by replacement with
cornea – goldmann contact lens
interface.

35. Technique for examination
• Dilate pupils
• Topical anaesthesia
• Insert coupling fluid into the cup of contact lens
• Ask the patient to look up, insert the inferior rim of contact
lens into the lower fornix and press it against the cornea
• Examine the vitreous cavity using central lens and then
examine the posterior pole and perephery using mirrors
• To visualize the entire fundus, rotate the lens for 360 deg
using the 59, 67 and 73 deg tilted mirrors
• To obtain a more peripheral view of retina, tilt the lens to
the opposite side and ask the patient to look in the same
side

36. Advantage
• Very high resolution
Disadvantage
• Limited field of view
• Cumbersome to use

37. Panfundoscopic lens
• Consists of a meniscus lens
coupled with a spherical lens
(high powered condensing)
• A real inverted image obtained in
the spherical glass element which
is within the focal range of slit
lamp microscope
Advantage
 Because the lens is close to the
eye and of such high power, field
of view is very wide, without
rotation of lens like the mirrored
lenses
 Can be used in poorly dilating
pupils
Disadvantage
 the image is small and periphery
not clear and hence Used more
often for laser photocoagulation
than diagnostic purposes

38. Mainster lens
• Has a biconvex, aspherical
anterior lens element and a
concave lens to fit to the corneal
curvature
• Provides a somewhat reduced
field of view compared to
panfundoscopic lens, but
produces higher magnification
(.92X)
• Good resolution for cases of
macular thickening
• Versatile for both diagnostic and
therapeutic purposes
• Image plane is anterior to lens
surface- therefore difficult to
view fundi of patients with
hyperopia or exophthalmos
• Mainster widefield (118 deg) and
mainster ultrafield PRP lens (165
deg) gives a greater field of view
and mainster high mag (1.25X)
gives a higher magnification

39. Comparison
Parameter Goldmann Panfundoscope Mainster
Anterior surface Flat Convex Spherical Convex Aspherical
Power -67 +85 +61
Image Type Virtual Erect Real Inverted Real, inverted
Image location Posterior Capsule Biconvex Lens Air
magnification 0.86 0.51 0.92
Field of view 18 Deg 60 Deg 45 Deg

40. • A real image of the fundus is formed at the slit lamp several centimeters in
front of the patient's eye when a high-powered plus lens is positioned in
front of the cornea.
• This aerial image of the fundus is magnified by the slit-lamp optics.
• The resultant image is real, inverted, and of high quality if a superior high-
power aspherical lens made for this purpose is used
• Lens power = + 78 or + 90 D , other lenses= + 60 to 132 D
• Field of view = 30 to 40 degrees
Indirect slit lamp biomicroscopy

42. Technique
• Set the slit lamp magnification to 10X or 16X
• Adjust the light intensity to minimum usable,
about halfway
• Slit beam-4mm wide
• Hold the lens in between the thumb and index
finger approx 5 to 10 mm from the patients
cornea
• Examine fundus using a joystick
• Increase the magnification for a greater detail as
necessary

43. • Video

44. • Drawing the slit lamp biomicroscopic view:
Done on an inverted fundus chart and paper is turned as
patients gaze direction changes in respective clock hour
meridian.
• Evaluating fundus :
Recording Findings

45. Tips on SLM BIO
• Use the patient’s optic
disc diameter as a
reference point when
determining the retinal
lesion’s dimensions.
• Always use a red free
filter soon after viewing
with normal yellow light
• Work up the optic nerve
with high magnification

46. • Examine macula clearly
Watzke-Allen test:
• you place a narrow slit-lamp beam over the fovea, then ask the patient to
look directly into the center of the beam and describe its overall
appearance.
• If the patient says that the beam looks unbroken and completely
rectangular, the macula is most likely intact.
• If, however, he or she reports that the beam appears narrow or distorted
in the center, this could indicate a partial-thickness (lamellar) hole.
• Finally, if the patient says the beam as looks broken in the center, he or
she may have a full-thickness hole.
• To perform the test accurately, it is helpful to present the beam both
horizontally and vertically
• If the macula of the opposite eye appears generally healthy, performing
the Watzke-Allen test in that eye may provide the patient with a point of
comparison.

47. Ophthalmologists health
• Compared to family
practice practitioners,
eye care professionals
report a much higher
incidence of neck, back,
hand and wrist pain
• Spinal disc prolapse or
spinal nerve
compression
• Carpal tunnel syndrome
• Cervical contractures
• Ulnar neuropathy

48. Remedies:
• Sitting in front of patient and
mobilizing the patient’s head
instead of doctor moving back
and forth
• Use 2 finger method to hold the
lens, speculum can be used to
keep eyes open
• When sitting behind the slit lamp,
take the extra time to raise or
lower the patient to a height
where examiner’s back remains
straight while looking through the
oculars.
• Years of performing fundus
biomicroscopy with elbow on the
table can lead to ulnar
neuropathy which can be avoided
using a foam pad on the SLM
table

49. Color Anatomic Feature
Red Retinal arteries, retinal
hemorrhage, attached retina,
retinal neovascularization
Blue Retinal veins, detached retina,
retinal edema
Green Media opacities, vitreous
hemorrhage
Yellow Retinal and choroidal exudates
Brown Pigmented lesions, choroidal
detachments
Red lined with blue Retinal breaks
Color Coding for Retinal Drawing

50. •Retinal arterioles
• Neovascularization
• Vascular anomalies
• Attached retina
• Vascular tumors
•Hemorrhages
( Pre- retinal and
retinal)
• Open interior of
retinal breaks
(tears, holes)
FUNDUS DRAWING – RED SOLID

51. • Open portion of Giant
Retinal Tears or large
dialyses
• Inner portion of thin
areas of retina
• Open portion of
retinal holes in inner
layer of retinoschisis
FUNDUS DRAWING- RED CROSSED

52. • Detached retina
• Retinal veins
• Outlines of retinal
breaks
• Outlines of ora
serrata
FUNDUS DRAWING – BLUE SOLID

53. FUNDUS DRAWING – BLUE SOLID
• VR traction tuft
• Outline of lattice
degeneration (inner X)
• Outline of thin area of
Retina

54. •Inner layer of retinoschisis
•White with or without
pressure (label)
•Detached parsplana
epithelium anterior to
separation of ora serrata
•Rolled edges of retinal tears
/ inverted flap in GRT (curved
lines)
FUNDUS DRAWING – BLUE CROSSLINES

55. • Opacities in the media
• Vitreous hemorrhage
• Vitreous membranes
• Hyaloid ring
• IOFB
FUNDUS DRAWING- GREEN SOLID

56. • Asteroid hyalosis
• Frosting or
snowflakes on
Retinoschisis or
lattice degeneration
FUNDUS DRAWING – GREEN DOTTED

57. • Uveal tissue
• Pigment beneath
detached retina
FUNDUS DRAWING – BROWN SOLID

58. • Pigment epithelial
Detachment
• Choroidal
melanomas
• Nevus
• Choroidal
detachment
FUNDUS DRAWING- BROWN SOLID

59. • Edge of buckle
beneath detached
retina
• Outline of
Posterior
Staphyloma
FUNDUS DRAWING – BROWN OUTLINE

60. • I/R, S/R hard
exudate
• S/R gliosis
• Deposits in the
RPE
FUNDUS DRAWING – YELLOW SOLID

61. • Post-cryo
retinal edema
• Substance of long
& short ciliary N
• Retinoblastoma
Yellow – stippled-
• Drusen
Yellow Crossed
• Chorioretinal
coloboma
FUNDUS DRAWING- YELLOW SOLID

62. • Hyperpigmentation as a
result of previous Rx
with cryo/laser/Diathermy
• Completely Sheathed
vessels
• Pigment within detached
retina (Lattice)
FUNDUS DRAWING- BLACK SOLID

63. • Pigment within choroid or
pigment epithelial
hyperplasia within
attached retina (e.g. RP)
• Pigment demarcation line
at margin of attached
and detached retina
FUNDUS DRAWING- BLACK SOLID

64. • Edge of buckle
beneath attached
retina
• Outline of Chorio
Retinal anastomosis
FUNDUS DRAWING – BLACK OUTLINE

65. References
• Retina and vitreous- Albert Jacobi
• Yanoff and Duker’s Ophthalmology
• Post Graduate Ophthalmology-Zia Chaudhri
• Theory and Practise of Optics and refraction-AK
khurana
• American academy of Optometry-binocular IDO
procedures
• Retinal Laser Optical Aids- Indian Journal of
Ophthalmology

66. Thank You