Optic Nerve Anatomy and Evaluation

1. PRESENTER: Dr. GARIYASHEE LAHKAR

2. OUTLINE OF THE PRESENTATION
 INTRODUCTION
 ANATOMY OF OPTIC NERVE HEAD
 BLOOD CIRCULATION
 METHODS OF EVALUATION
 EXAMINATION OF OPTIC NERVE HEAD
 APPEARANCE OF OPTIC NERVE HEAD IN
 SUMMARY
 GLAUCOMA
 CONGENITAL ANOMALIES OF OPTIC DISC
 PAPILLEDEMA
 INFLAMMATORY OPTIC NEUROPATHIES
 ISCHEMIC OPTIC NEUROPATHIES
 TRAUMATIC OPTIC NEUROPATHIES
 OPTIC ATROPHY

3. INTRODUCTION
 The optic nerve head is composed of axons from RGCs, as well as blood vessels and astroglial and collagen support.
 The optic nerve head can be evaluated by various clinical methods as well as imaging techniques.
 The evaluation of optic nerve head is central to the diagnosis and management of a lot of conditions.
 With proper documentation, it helps in quantifying the amount of damage in the ONH and also monitor the change.
 Technological advancements help in detection of early optic nerve head damage.
 The optic nerve head evaluation has got considerable significance in the diagnosis and follow-up of glaucoma.

4. ANATOMY
 Optic nerve head is the distal portion of the optic nerve.
 Optic disc and papilla are referred to the portion of the optic nerve
head clinically visible by direct ophthalmoscope.
 Extends from retinal surface to the myelinated part posterior to the
lamina cribrosa.
 Composed of nerve fibres originated in ganglion cell layer,
converges upon ONH as neuroretinal rim (NRR) and exits the
globe.
Optic disc

5. ANATOMY…
 1.5 mm in length
 May be arbitrarily divided into :
1. Surface Nerve Fibre Layer
2. Prelaminar Region
3. Lamina Cribrosa Region
4. Retrolaminar Region
Parts of Optic nerve head

6. ORGANISATION OF NERVE FIBRES IN
OPTIC NERVE HEAD
 Fibres from central region pass straight to form the
papillomacular bundle.
 Fibres from nasal half come directly as superior and
inferior radial fibres.
 Fibres from temporal region arches over the the pmb
forming the superior and inferior radial fibres.
 Axons from peripheral retina takes a peripheral position
in the optic nerve head.
Figure : Distribution of retinal nerve fibers

7. BLOOD SUPPLY
 Central Retinal artery
 Short posterior ciliary artery –
Circle of Zinn / Haller
 Pial vasculature
Figure : Blood supply optic nerve head

8. BLOOD SUPPLY…
Figure : Blood supply optic nerve head

9. BLOOD SUPPLY…
ARTERIAL SUPPLY :
• Surface nerve fibre layer : central retinal artery, cilioretinal artery (occasionally)
• Prelaminar region : short posterior ciliary arteries
• Lamina cribrosa region : short posterior ciliary arteries, arterial circle of Zinn-Haller
• Retrolaminar region : pial vessels, short posterior ciliary vessels , central retinal artery
VENOUS DRAINAGE :
• mainly by central retinal veins , small portion by choroidal system.

10. EVALUATION OF
OPTIC NERVE HEAD

11. METHODS OF EVALUATION OF
OPTIC NERVE HEAD
 CLINICAL EXAMINATION :
a. Visual Acuity
b. Pupil Examination
c. Colour Vision
d. Spatial Contrast Sensitivity

12. STRUCTURAL ANALYSIS:
 Direct Ophthalmoscopy
 Indirect Ophthalmoscopy
 Slit Lamp Biomicroscopy
 HRT
 Scanning Laser Polarimerty
 OCT
METHODS OF EVALUATION OF
OPTIC NERVE HEAD
FUNCTIONALANALYSIS
 Visual Field Analysis
 ANCILLARY TESTS
• Ultrasound
• MRI
• CT Scan
• FFA

13. DIRECT OPHTHALMOSCOPY
 Simplest and commonest method of disc evaluation.
 The basic principle of direct ophthalmoscopy
 Disadvantage: Lack of stereopsis

14. INDIRECT OPHTHALMOSCOPY
 3 D Visualization
 The basic principle of indirect ophthalmoscopy
 Disadvantage: poor magnification

15. SLIT LAMP BIOMICROSCOPY
 Current gold standard.
 To visualize - Optic nerve head , peri papillary changes
- Nerve fibre layer thickness [red free filter]
Non-contact lenses
(+60D, +78D, +90D)
Contact lenses

16. SLIT LAMP BIOMICROSCOPY…
• The slit lamp viewing piece and the light column are kept coaxial.
• Intensity of the beam is kept brightest.
• Magnification preferably set at 10× initially.
• The slit beam is set around 1.5–2.5mm wide and 5–10mm long.
• Beam is focused at around 5 to 10 mm from thepatient’s eye.
• Increase the width of the beam to obtain larger field of view.
• Increase the magnification for greater details as necessary.
• Appropriate positions of gaze allows visualisation of
peripheral retina

17. 1. Excellent stereoscopic and magnified view of the optic disc.
2. Better image achieved when viewing through media opacities -
Cataract.
3. Allows for manipulation of image- Slit lamp magnification and
filters.
4. Image size less affected by patient refractive status.
5. Quick and inexpensive method.
SLIT LAMP BIOMICROSCOPY
ONH viewed with 90D
Non Contact Lens in Slit Lamp

18. HRT
(HEIDELBERG RETINAL TOMOGRAPH)
 Precise observation and documentation of optic nerve head.
 Based on confocal scanning laser ophthalmoscopy principle.
 Non-contact, non-invasive method.
 Uses 670nm He-Ne diode laser to take 3D pictures of optic nerve head.
 Essential for diagnosis and management of Glaucoma.

19. HRT
(HEIDELBERG RETINAL TOMOGRAPH)

20.  Confocal scanning laser ophthalmoscope with integrated
polarimeter
 Uses a near-infrared laser beam (780 nm) to scan the retina
 The retardation of the reflected light is then measured for an
estimation of RNFL thickness.
 Painless, less time consuming, pupils need not be dilated.
GDx VCC
(GLAUCOMA DETECTION WITH VARIABLE CORNEAL COMPENSATION)

21. GDx VCC
(GLAUCOMA DETECTION WITH VARIABLE CORNEAL COMPENSATION)

22. OCT
(OPTICAL COHERENCE TOMOGRAPHY)
 Scans the ONH, peripapillary retina and macular region.
 Non-contact, non-invasive imaging technique.
 Near-infrared light beam is used.
 The intensity of light signal reflecting from retinal structures
is used to create a tomographic image.
 The combined use of low-coherence light and an
interferometer provides high depth resolution.

23. OCT
(OPTICAL COHERENCE TOMOGRAPHY)
Optical coherence tomography printout

24. OCT ANGIOGRAPHY
 Functional extension of OCT.
 Newer, non-invasive diagnostic technique.
 Allows visualisation of blood flow in the retina and
choroid without injection of contrast medium.
 Based on the detection of red blood cell movement
within the microvasculature of the eye.
 Uses series of OCT B-scans.

25. VISUAL FIELD ANALYSIS
 Perimetry is used for systematic measurement of visual
field function.
 Useful in:
 Optic disc lesion
 Detection of glaucoma, progression
 Chorioretinal lesions

26. FFA
(FUNDUS FLOURESCEIN ANGIOGRAPHY)
 Adjunctive diagnostic tool aids the diagnosis of retinal vascular and macular diseases.
 Useful in :
• Papilledema
• Anterior Ischemic optic neuropathy
• Optic Nerve Head Drusen
• Optic nerve coloboma
• Diabetic Retinopathy

27. 1. DISC
2. NEURORETINAL RIM
3. CUP
4. VESSELS
5. OPTIC NERVE HEAD HAEMORRHAGES
6. PERIPAPILLARY AREA
7. RETINAL NERVE FIBRE LAYER
EXAMINATION OF OPTIC
NERVE HEAD

28. EXAMINATION OF OPTIC
NERVE HEAD

29. EXAMINATION OF OPTIC
NERVE HEAD…

30. CLINICALAPPEARANCE OF
OPTIC NERVE HEAD
Figure : Normal optic nerve heads

31. OPTIC DISC
 Shape: The normal shape of the optic disc is slightly vertically oval.
 Size: There is wide variation in the size of the discs.
i. Small discs: <1.50 mm
ii. Medium discs: 1.50–2.50 mm
iii. Large discs: >2.50 mm

32. MEASUREMENT OF
OPTIC DISC SIZE
 SLIT LAMP BIOMICROSCOPY:
 DIRECT OPHTHALMOSCOPE
Small aperture (5 degree) of Welch –Allen
direct ophthalmoscope has a diameter of
1.5 mm and an area of 1.77 mm2.
Size of light spot ~ size of average optic disc Area= Π/4 x vertical diameter x horizontal diameter

33. PAPILLARY CHANGES IN GLAUCOMA
 SIZE:
o Overdiagnosing large CDRs in large discs
-not glaucoma if NRR,RNFL etc normal.
o Underdiagnosing average CDR in small discs
with or without ocular hypertension.
o Early or moderate GON may be overlooked in
small discs because of “pseudo-normal”
appearance.

34. • The tissue between the cup and the disc margins is referred
as the neural rim.
• Uniformly orange red in colour.
• The neuroretinal rim is the most important parameter of the
optic disc evaluation.
• For every 1 mm2 increase in disc area, the rim area increased
by 0.5 mm2
NEURORETINAL RIM

35. ISNT RULE
• It is broadest in inferior quadrant, followed by superior and then nasal, temporal being the thinnest (ISNT RULE)
Inferior > Superior > Nasal > Temporal rim

36. NORMAL VARIATIONS OF NRR
Slate gray crescent
• Variation of the normal anatomy
• Located in the temporal or
inferotemporal periphery
Oblique insertion of nerve in myopic
• Obfuscate the interpretation of the NRR
• Distortion of temporal rim

37.  Loss Of NRR - Generalized Or Focal
ABNORMALITIES IN NRR
 Notch is defined as localized defect in the NRR
on the cup side of the rim

38. NEURO RETINAL RIM CHANGES IN
GLAUCOMA
VIOLATION OF ISNT RULE

39.  The cup is the central portion of disc, which represents a partial or
complete absence of axons, with exposure of lamina cribrosa .
 Size : Mean cup area is 0.72 mm2
 Shape: Shape of the optic cup is horizontally oval
 Depth: cup depth is somewhat proportional to the cup area
 Cup to disc ratio: Ratio of cup and disc with measured in same meridian.
 As the disc is vertically-oval and cup is horizontally-oval,
vertical C/D < horizontal C/D
OPTIC CUP

40. COLOUR CUPPING V/S CONTOUR CUPPING

41. OPTIC CUP CHANGES IN GLAUCOMA…
Notching

42. OPTIC CUP CHANGES IN GLAUCOMA…
Different pattern of Glaucomatous cupping
A) Diffuse B) Unipolar C) Bipolar

43. OPTIC CUP CHANGES IN GLAUCOMA

44. • DEEPENING OF THE CUP
• It is the predominant pattern of early glaucomatous
optic atrophy.
• Exposure of lamina cribrosa by the deepening cup
shown by gray fenestra of lamina: laminar dot sign.
• Seen ophthalmoscopically as dotlike or striate
appearance.
OPTIC CUP CHANGES IN GLAUCOMA…

45. OPTIC CUP CHANGES IN GLAUCOMA…
• In late glaucoma loss of all neural rim tissue occurs leading to
total cupping.
• Clinically : white disc with total loss of NRR and bending of
all vessels at margin of disc.
• Extreme posterior displacement of lamina cribrosa and
undermining of disc margin is seen on cross section.
• Known as Bean potting/‘shelving’

46. OTHER PAPILLARY CHANGES
IN GLAUCOMA
Saucerizatio
n
SAUCERIZATION:
When diffuse shallow cupping extends to the disc margin with retention of a central pale cup

47. TINTED HOLLOW:
The retention of normal neural rim color in the area of focal saucerization is called the Tinted hollow
OTHER PAPILLARY CHANGES
IN GLAUCOMA

48. Pallor-cup discrepancy : Important marker to differentiate between GOA and Non -GOA
In GOA,
Area of cup> area of pallor
In non-GOA,
Area of pallor >area of cup
OTHER PAPILLARY CHANGES
IN GLAUCOMA

49. • The retinal vessels emerge on the medial side of the cup.
• CRA divides dichotomously into 4 branches.
• The course of the veins and arteries is similar but not identical
• Cilioretinal artery is present in 40% population.
RETINAL VESSELS

50. EXAMINATION OF VESSELS
 Origin : CRA enters globe through the cup.
 Branching : Divides dichotomously within cup and surface of disc.
 Course: Veins lie temporal to arteries.
 Diameter: Arterioles: Venules = 2:3
 Colour: Veins/venules are purplish red while artery/arterioles are
bright light red
 Pulsation: Venous pulsation is noted at the sharp bend around the
optic nerve head.

51. VASCULAR CHANGES IN GLAUCOMA
DISC HAEMORRHAGES :
• Also known as Splinter/Drance haemorrhages
• More common in NTG
• Most common location – inferior quadrant
• May reappear at the same or different site.
• Not pathognomonic, but may be the first sign of glaucoma.
• Localised on or within 2 clock hours of an RNFL defect.

52. VASCULAR CHANGES IN GLAUCOMA…
BARING OF CIRCUMLINEAR VESSELS :
• Normally, circumlinear blood vessels rest on NRR tissue.
• Occurs in areas of focal NRR loss or notching.
• Often occurs normally and not pathognomonic of glaucoma.
• Characterized as unsupported appearance of ‘suspending’ or
‘hanging in mid-air’ of the vessels crossed over the optic cup.

53. VASCULAR CHANGES IN GLAUCOMA…
NASALIZATION OF BLOOD VESSELS IN ONH:
• Normally, blood vessels enter and leave the eye along nasal
border of cup.
• Nasalization of ONH vessels is a function of cup size- may be
physiological or as in advanced glaucomatous cupping.
• Due to loss of superior, inferior, and temporal NRR & presence
of structural support only in nasal NRR.

54. VASCULAR CHANGES IN GLAUCOMA…
OVERPASS CUPPING :
• Normally, vessels run over surface of disc and NRR and then
come out.
• Loss of NRR takes away the support.
• Vessels appear to hang over the disc , bridging the cup-
overpass cupping

55. VASCULAR CHANGES IN GLAUCOMA…
BAYONETING :
• When the local thinning of NRR reaches the disc margin, a
sharpened rim is produced.
• A retinal vessel crossing the sharpened rim bends sharply at
the edge of disc creating bayoneting at disc edge.

56. OPTIC NERVE HEAD
HAEMORRHAGES
 Have relatively high specificity but relatively low sensitivity for glaucoma.
 Predictor for visual field loss with a faster rate of visual field progression.
 Other optic nerve diseases can have disc hemorrhages:
optic disc drusen, retinal vascular occlusive diseases, and systemic
conditions.
 Can be located within the
Optic disc tissue ,
Neuroretinal rim, or
Parapapillary zone.

57. PERIPAPILLARY AREA
• Crescentic region of chorioretinal atrophy is a common finding at
the temporal margin of normal discs.
• Alpha Zone:
1. Hypo and Hyper pigmented areas
2. Present in glaucomatous as well as non-glaucomatous
• Beta Zone:
1. Large choroidal vessel become visible
2. More common in glaucomatous eyes

58.  Retinal nerve fiber layer (RNFL) is seen as
striations in the light reflexes from bundles of nerve
fibers.
 Can be best seen with green light or red free light.
 Observe
1. Brightness,
2. Striations,
3. Visibility of peripapillary blood vessels,
4. Diffuse or localized nerve fiber loss.
RETINAL NERVE FIBER
LAYER

59. PATTERNS OF RNFL LOSS
 Localised:
1. Slit like/Groove like defect
2. Wedge shaped defect
Localised wedge shaped RNFL defect

60. PATTERNS OF RNFL LOSS
 Diffuse :
Diffuse/Generalised RNFL Loss
• Diffuse RNFL loss
• Diffuse loss of striate
pattern
• Increased visibilty of
retinal vessels

61. 1. RNFL defects
2. RNFL haemorrhages
3. Peripapillary pigmentation
PERIPAPILLARY CHANGES IN GLAUCOMA

62. This includes asymmetry in:
• Size of the cup ( >0.2)
• Width of NRR.
• Vessel course.
• Peripapillary atrophy.
ONH ASYMMETRY IN GLAUCOMA

63. FIVE STEPS FOR ASSESSMENT OF THE OPTIC
NERVE HEAD IN GLAUCOMA
1. Observe the scleral Ring to identify the limits of the
optic disc and it’s size.
2. Identify the size of the Rim.
3. Examine the Retinal nerve fiberlayer
4. Examine the Region of parapapillary atrophy
5. Look for the Retinal and optic disc hemorrhages.

64. CONGENITALANOMALIES
OF OPTIC DISC

65. CONGENITALANOMALIES
OF OPTIC DISC
• Bergmeisters Papilla
• Myelinated Nerve fibre
• Hypoplasia of optic nerve
• Optic disc coloboma
• Tilted optic disc
• Optic disc pit
• Morning Glory Syndrome

66. PAPILLEDEMA

67. PAPILLEDEMA
 Oedema of the Optic Nerve Head due to raised intracranial pressure.
 Pathogenesis:
1. Blockage of axoplasmic transport
2. Compression of central retinal vein
 Etiology:
• Intracranial Tumor
• Brain abscess
• Cavernous sinus thrombosis
• Pseudotumor cerebri
Blurred disc margins in Papilledema

68. Early Established
Chronic Atrophic
PAPILLEDEMA…
 Stages of papilloedema
• Early
• Established
• Chronic
• Atrophic
TREATMENT:
Relief of causal pressure.

69. INFLAMMATORY OPTIC
NEUROPATHIES

70. OPTIC NEURITIS
 Inflammation of the optic nerve
 According to ophthalmoscopic appearance:
1. Retrobulbar neuritis
2. Papillitis
3. Neuroretinitis
 According to etiology:
1. Demyelinating
2. Parainfectious
3. Infectious
4. Non-infectious
TREATMENT:
• Treat the underlying cause
• Use of steroids as per Optic neuritis treatment trial (ONTT) recommendations

71. OPTIC NEURITIS…

72. ISCHEMIC OPTIC
NEUROPATHIES

73.  Acute, painless optic neuropathy occurring predominantly in patients over 50 years of age due to optic nerve ischemia.
 It Includes:
1. Non-arteritic anterior ischaemic optic neuropathy
2. Arteritic anterior ischaemic optic neuropathy
3. Posterior ischaemic optic neuropathy
4. Diabetic papillopathy
ISCHEMIC OPTIC NEUROPATHIES

74. NON-ARTERITIC
ANTERIOR ISCHAEMIC
OPTIC NEUROPATHY
(NAION)
ARTERITIC ANTERIOR
ISCHAEMIC OPTIC
NEUROPATHY
DIABETIC
PAPILLOPATHY
ISCHEMIC OPTIC NEUROPATHIES

75. TRAUMATIC OPTIC
NEUROPATHY

76.  Follows ocular, orbital or head trauma .
 Presents with sudden visual loss .
 The optic nerve head and fundus are initially normal.
 Pallor develops over subsequent days and weeks .
 Spontaneous visual improvement occurs in up to about half of patients.
 Steroids (intravenous methylprednisolone) should be considered.
 Optic nerve decompression may be considered.
TRAUMATIC OPTIC
NEUROPATHY

77. OPTIC ATROPHY

78.  Late stage changes that take place in the optic nerve
 Results from axonal degeneration in the pathway between the retina
and the lateral geniculate body
 Important causes
○ Optic neuritis
○ Compression by tumours and aneurysms
○ Hereditary optic neuropathies
○ Toxic and nutritional optic neuropathy
○ Trauma
OPTIC ATROPHY

79. PRIMARY
Disc margins well
defined
Chalky white disc
Vessels normal
Periphery normal
SECONDARY
Ill defined disc
margins
Grey white disc
Sheathing present
May/may not be
normal
CONSECUTIVE
Disc margins well
defined
Waxy pale disc
Attenuated vessels
Pigments or
degeneration
OPTIC ATROPHY

80. SUMMARY
 The optic nerve head is the distal portion of the optic nerve which is actually a continuation of the ganglion cell layer.
 The normal optic nerve has considerable variation in size and contour.
 Examination of the optic nerve head is one of the simplest and most overlooked skills in ophthalmology.
 Clinical examination of optic nerve head is qualitative and needs documentation.
 Computed imaging analysis and blood flow measures provide more precise method of observation.
 Glaucoma, despite its multifactorial etiology, is an optic neuropathy with characteristic quantitative and qualitative optic nerve
defects.
 Epidemiology and statistics have shown that ONH assessment is superior to tonometry and perimetry for diagnosis and follow up of
glaucoma patient when all these tests are used individually.

81. REFERENCES
 Allingham, R. Rand. Shields Textbook of Glaucoma, 6th Ed. 2011
 Diagnostic Procedures in Ophthalmology- H V Nema - 3rd Ed
 Anthony J. Bron. Wolff’s Anatomy of the Orbit, 8th Ed. 1997, p 279-282
 Brad Bowling. Kanski’s Clinical Ophthalmology, 8th Ed. 2016, p 306-316
 Myron Yanoff, Jay S Duker. Yanoff Duker Ophthalmology, 5th Ed. 2019
 Parsons’Diseases of the Eye, 22nd Ed. 2017, p 287-308
 Oliveira C, Harizman N, Girkin CA, Xie A, Tello C, Liebmann JM,Ritch R. Axial length and optic disc size in
normal eyes. Br JOphthalmol 2007 Jan;91(1):37-39.
 Jonas JB, Fernández MC. Shape of the neuroretinal rim and position of the central retinal vessels in glaucoma. Br
J Ophthalmol 1994Feb;78(2):99-102
 Images and Videos for Internet –
 •https://www.google.com
 •http://en.wikipedia.org
 •https://www.youtube.com