Direct ophthalmoscopy involves examining the retina using an ophthalmoscope held close to the patient's eye, providing a magnified inverted image. Indirect ophthalmoscopy uses a condensing lens placed near the eye to render it highly myopic, producing an upright magnified image seen by the examiner. Both methods allow assessment of the retina but indirect provides a wider field of view and is better for opaque media or uncooperative patients. The document describes the techniques, advantages, and applications of direct and indirect ophthalmoscopy.

1. DIRECT AND INDIRECT
OPHTHALMOSCOPY
Mr. Mahenddra Singh
PhD (Scholar)
M.Optom
FLVPEI (Hyderabad)

2. Introduction
• Ophthalmoscopy is a clinical examination of the
interior of the eye by means of an ophthalmoscope.
• It is primarily done to assess the state of fundus and
detect the opacities of ocular media.
• The ophthalmoscope was invented by Von Helmholtz
in 1850.

3. Structures of the retina
Nasal Temporal

4. Optic disc
• DISC: LOCATION –nasal to geometric axis
• DIAMETER – 1.5mm [1 disc diameter]
• COLOR – Pale pink
• SHAPE – Circular
• EDGES – Regular
• Termination of all layers except NFL
• CUP: C/D ratio – 0.3 to 0.5

5. Vessels
 RETINAL SYSTEM :
CENTRAL RETINAL ARTERY
AND
CENTRAL RETINAL VEIN
Arterioles,Venules,Capillaries
 CILIARY SYSTEM : POST.CILIARY ARTERIES
Choriocapillaries

6. Macula
• Specialised region of retina
• Diameter – 5.5 mm
• Location – 2 DD - temporal margin of disc
• Color – Yellow; deep pigmented
• 4 zones : Foveola -0.35 mm
Fovea -1.50 mm
Parafovea
Perifovea
• Retinal vessels
• Cilioretinal artery

7. Continue…
• Ophthalmoscopic methods of examination are-
(1) Distant direct ophthalmoscopy
(2) Direct ophthalmoscopy
(3) Indirect ophthalmoscopy

8. Direct ophthalmoscope
• Parts-
• Light source
• Eyepiece
• Lens rack and power dial
• Aperture selector
• Filter selector
• On/off and brightness control
• Power handle

9. Method
• For a good view of fundus the pupil should be
dilated by instilling few drops of short acting
mydriatic drug (e.g. combination of tropicamide and
phenylephrine).
• The subject should be examined in sitting or lying
down position.
• Examination room should be semidark.
• keep the eye as still as possible.

10. Position of the examiner
For examining right eye of the patient,
• Examiner should stand on right side of the
patient.
• Hold the instrument in his right hand.
• Use examiner’s right eye.
• If examining left eye, stand on left side, hold
instrument in left hand use left eye.

11. Conti..
• Viewing should begin about half meter away
from the eye.
• First see the “Red reflex”
• Initially the lens power in the instrument should be
set to zero, and if refractive error present in patient or
examiner, e.g. if the patient is myopic then set the( -
ve )lens, if the examiner or patient is hypermetropic
then set the lens to (+ve) lens. If both patient &
examiner have refractive error then sum together their
powers.

12. Conti….
• Rotate the lens dial until the optic disc is focused
clearly.
(Red numbers/negative numbers in myopia or short-
sighteness.
Green numbers/positive numbers in hyperopia or far-
sightedness.
• Examine the optic disc for:
Shape – normally round or slightly oval
Clarity -of the outline-clear outline or rim
Colour-pale pink contrast to rich red of rest of fundus.

13. Conti…
• Examine the macula last.
• To locate the macula, focus on the disc, then move 2
disc diameters temporally. The macula is darker in
colour than the surrounding fundus, and devoid of
blood vessels.
• May also ask the patient to look at the light, this
automatically puts the macula into full view.

14. Examiner right eye, hand, right
patient eye

15. Distant direct ophthalmoscope
• It should be performed routinely before the direct
ophthalmoscope,as it gives a lot of useful
information.
• It can be performed with the help of a self-
illuminated ophthalmoscope or a simple plain mirror
with a hole at the centre.
• Procedure- The light is thrown into patients eye
sitting in a semi-darkroom, from a distance of 20-25
cm and the features of thred glow in the pupillary area
are noted.

16. Application
• To diagnose opacities in the refractive media- any
opacity in the refractive media is seen as a black
shadow in the red glow.
• To differentiate between a mole and a hole of the
iris- a small hole and mole on the iris appears as a
black spot on oblique illumination
• To recognise detached retina or a tumour arising
from the fundus is seen as a greyish reflex.

17. Direct ophthalmoscopy
• It is the most commonly practised method for routine
fundus examination.
• It works on the basic optical principle of glass plate
ophthalmoscope introduced by von helmholtz.
• A convergent beam of light is reflected into the
patients pupil. The emergent rays from any point of
the patients fundus reach the observers retina through
the viewing hole in the ophthalmoscope.

18. Conti….
• The emergent rays from the patients eye are parallel
and brought to focus on the retina of the emmetropic
observer when accommodation is relaxed.
• In hypermetropic patient,the emergent rays will be
divergent and with the help of convex lens can be
brought to focus on the observers retina.
• In myopic patient,the rays will be convergent and use
concave lens for focus on the observers retina.

19. Optics of ophthtlmoscopy

20. Conti..
• The image is erect, virtual and about 15 times
magnified in emmetropes.
• Technique- should be performed in a semi-darkroom
with the patient seated and looking straight ahead ,
while the observer standing or seated slightly over to
the side of the eye to be examined by the observer
with his or her right eye and left with the left.

21. Conti..
• The observer should reflect beam of light from the
ophthalmoscope into patients pupil.Once the red
reflex is seen the observer should move as close to
the patients eye as possible.
• Once the retina is focused the details should be
examined systematically starting from disc, blood
vessels, the four quadrant of the general background
and the macula.

22. Monocular indirect ophthalmoscopy
• 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,
and Iris diaphragm lever to adjust the illumination
beam diameter.

23. Conti..
• 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.
• Indications are-
• Need for an increased field of view
• Small pupils
• Uncooperative children
• Patients intolerance of bright light of binocular
indirect ophthalmoscope.

24. Conti..
• Extent of view- although vitreous base views are
possible with monocular IO, its greatest effectiveness
extends anteriorly to the peripheral equatorial region.
• Advantage- field of view similar to IO and,
• Erect real image similar to DO.
• Disadvantage –are lack of stereopsis,
• Limited illumination and,
• Fixed magnification.

25. Indirect ophthalmoscopy
• It is very popular method for examination of
posterior segment introduced by Nagel in 1864.
• PRINCIPLE-
• To make the eye highly myopic by placing a strong
convex lens in front of patients eye so that the
emergent rays from an area of the fundus are brought
to the focus as a real,inverted image between the lens
and the observers eye.

26. Indirect ophthalmoscope

27. Cont…
• An inverted reverse real image
• Magnification = 2 to 4 X
• Field of view = 40 to 50 degrees
• Optimal working distance = 40 to 50 cms
• Good illumination & stereopsis
• Ease of use with scleral indentor
• Lenses from 14 to 30 D range

28. Conti..
• CHARACTERISTICS- Magnification of image
depends upon the dioptric power of convex lens,
position of the lens in relation of the eyeball and
refractive state of eyeball.
• About 5 times magnification is obtained with +13 D
lens.
• With a stronger lens,image will be smaller, but
brighter and field of vision will be more.

29. Prerequisites
(1) Dark room
(2) source of light and concave mirror or self
illuminated indirect ophthalmoscope
(3) Convex lens
(4) pupils of the patient should be dilated.

30. Technique
• The patient is made to lie in the supine position, with
one pillow on a bed or couch and instructed to keep
both eyes open.
• The examiner throws the light into patients eye from
an arms distance.
• In practise, Binocular ophthalmoscope with head
band or that mounted on the spectacle frame is
employed most frequently.

31. Conti..
• Keeping his or her eyes on the reflex, the examiner
then interposes the condensing lens in the path of
beam of light, close to the patient eye, and then
slowly moves the lens away from eye until the image
of retina is clearly seen.

32. Contin..
• The examiner moves around the head of the patient
to examine different quadrants of the fundus.
• He or she has to stand opposite to clock hour
position to be examined.
• 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.

33. Scleral indentation
• Helps in making prominent the barely perceptible
lesions, done with the depressor placed on patients
lid.
• Examiner should move the scleral depressor in a
direction opposite to that in which he or she wishes
the depression to appear.
• Scleral depressor should be rolled gently and
tangentially over the eye surface.
• The temporal part of upper lid is sufficiently lax so
depressor can be placed inferiorly in the horizontal
meridian.

34. Fundus diagram

35. Disadvantage
• Technique is difficult and can be mastered by hours
of practice.
• Magnification is less compare to DO.
• It is impossible with very small pupil.
• Patient is usually more uncomfortable with intense
light of IO and with scleral ndentation.
• Reflex sneezing can occur on exposure to bright light.

36. Advantage of indirect system
• Image not affected by the patients refractive power
• In eyes with nystagmus
• Delivery of LASER
• Binocular examination of fundus up-to the periphery
• Large field of view allow for the panoramic view
• Better Resolution
• Use in operating room for cryo/scleral buckling
• Better view in presence of media opacities
• Increased illumination
• Reduced distortion

37. Direct versus indirect ophthtlmoscopy