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Recommended Books for
Ophthalmology
1.

Vaughan & Asbury’s
General Ophthalmology
16th Edition 2004 a LANGE medical book

•...
GLAUCOMA
Patho-physiology & Detection
Dr. Nasir Saeed
Epidemiology of Glaucoma
Glaucoma is not a single disease entity,but the result of a group
of different mechanisms which c...
Glaucoma prevalence surveys, by racial groups
Location

Age

PACG (%)

POAG (%)

Secondary
glaucoma

Congenital/
Developme...
World estimates of glaucoma prevalence

Affected
Congenital
300 000
POAG
13.5 million
PACG
6 million
Secondary
2.7 million...
RISK FACTORS
Age:
The prevalence and incidence of PACG
increase with age. Although a peak has been
claimed, the best evide...
 GENDER
• POAG
• PACG
 Race

• Chinese
• European
• Africans
• Japanese
• Asians

 Refraction
• ACG
• POAG

Genetics

...
• Intra-ocular Pressure
• Diabetes
• Family History
• Hypertension
• Vascular Spasm
ANATOMY OF THE ANGLE STRUCTURES
Aqueous Humour
Produced by the ciliary processes into the posterior chamber
• Through the pupil it circulates into the ant...
Functions of Aqueous humour

 It maintains the shape and internal structure of the eye by
sustaining an intraocular press...
Aqueous humour production
• Produced by the ciliary processes of the ciliary body.
Two Mechanisms
I- Active secretion
• 80...
Aqueous humour production
II- Passive Secretions
• 20%
• Diffusion
to maintain equilibrium between the osmotic pressure
an...
Intra-ocular pressure (IOP)
• The circulation of aqueous humour in the eye maintains the IOP
• The equilibrium of aqueous ...
Determinants of Intraocular Pressure

•

Rate of aqueous humour formation

•

Resistance encountered in out flow channels
...
Factors influencing Intra-Ocular Pressure
I- Rate of Aqueous Humour formation
Increased by
a. Inflammation
b. Blood Pressu...
II- Out flow Resistance
Increased by
Age
Membrane
• Pupillary Block

Synechia
Lens
Vitreous

• Trabecular Meshwork block
I...
• Outflow Resistance Decreased by
• Accommodation
• Drugs
• Miotics
• Prostaglandins
• Adrenaline
III- Episcleral Venous Pressure

Increased by
• Increased CVP
• Valsalva
• Carotid Cavernous fistula
• Hypercarbia
•Dysthy...
Applied Anatomy of the optic n. head
Retinal Nerve fibre layers
Relative positions of nerve fibre layer
Cross Section of the Optic N. Head
Optic Cup & Neuro-retinal rim
Physiological Cup & Neuro-retinal rim
Glaucomatous Damage Retinal Nerve fibre layers Normal
Glaucomatous Damage Abnormal Nerve fibre layers
Abnormal nerve fibre layers
Glaucomatous Damage
Optic disc cupping
Bilateral glaucomatous cupping with inferior notching and
‘bayonetting’
Bilateral advanced glaucomatous cupping with nasal
displacement of the blood vessels
End – Stage glaucomatous cupping
Clinical Methods for detection and evaluation of
glaucoma

• IOP Measurements
• Gonioscopy
• Perimetry Techniques
• Advanc...
Measurement of Intraocular Pressure Tonometry
Principal
• The pressure inside a sphere may be measured directly by canulat...
Goldmann Applanation Tonometer
• Applanation tonometry measures the force applied per unit area. The
Goldmann tonometry is...
Goldmann applanation
tonometer
Fluorescein-stained semicircles seen during tonometry
A- Schiotz tonometer

B- Principles of
indentation tonometry
•

Checking for diurnal changes= phasing

•

Demonstrating elevation of IOP after pupillary

dilation, water drinking
•

I...
Gonioscopy
•

Visualization of the anterior chamber angle is called
Gonioscopy

Purposes
1. Diagnostic:

to identify abnor...
Optical Principal
• In normal circumstances the angle of anterior chamber can not
be visualized because of the total inter...
Optical Principal of Gonioscopy
Single Mirror goniolens & Zeiss four mirror goniolens
Swan-Jacob surgical goniolens & Koeppe goniolenses
Normal Anatomy of Angle structure
Schaffer’s Grading System
Abnormal Anterior Chamber Angle
Perimetry
• Visual fields ;
• An island of vision surrounded
by a sea of darkness
• Isopter.

An Isopter is a line in the field of vision exhibiting
similar visual acuity

• Scotoma.

Is a defect in the v...
Perimetric Principals

• Perimetry is a method of evaluating the visual fields
• Qualitative Perimetry is a method of dete...
Visual Fields defects in glaucoma
1. Arcuate scotomas : develop between 100 and 200 of
fixation in areas that constitute d...
1. Arcuate scotomas : develop between 100 and 200 of fixation in
areas that constitute downward or more commonly, upward
e...
Isolated paracentral scotomas: superior or inferior scotomas may also
be found in early glaucoma
A nasal (Roenne) step
Temporal Wedge
End Stage fields defects
Advanced Techniques

Quantitative Measurements
• Digitalized photogrammetry
• Confocal scanning laser ophthalmoscope (HRT)...
Digitalized photogrammetry
Confocal scanning laser
ophthalmoscope (HRT)
Glaucoma is the second leading cause of
worldwide blindness.
Early detection and early onset of treatment are
the most imp...
The aims of assessment are:
 To assess the risk factors to determine whether

glaucoma is present or likely to develop
 ...
ASSESSMENT
Presenting

Social

HISTORY

Family

Past
VA
Gonio

OM

IOP

Exoph

EXAMINATION
Fundus

Ocu surf

Cornea

Lens
Pupils

AC
Ocular Examination
 Record visual functions
 Ocular motility
 Exclude any proptosis/exophthalmos
 Ocular surface for e...
Ocular Examination


Anterior chamber for inflammation, blood, pigment



Check for AC depth, central and peripheral

• ...
Ocular Examination
Iris for atrophy , rubeosis, trans-illumination defects and pseudoexfoliation

Stromal iris atrophy wit...
Ocular Examination
 Pupil for size, shape and reaction
 Lens for presence, transparency,

thickness, position and shape
Ocular Examination




Record intraocular pressure, look for
diurnal variations
Evaluate IOP for 24 hours if in doubt
U...
Ocular Examination
Gonioscopy: look for width of the angle, configuration of the iris and
chamber, PAS, vessels and iris p...
Ocular Examination
Fundoscopy: evaluate optic nerve head and retinal nerve fibre layer
use slit lamp indirect lenses and a...
Optic disc evaluation
Retinal nerve fibre layer analysis
Investigations
Order for a visual field
examination with a
standard automated
perimeter
Investigations
HRT
OCT
GDx
Systemic investigation include
Imaging of CNS
Evaluation of CVS
Haematological profile
Anatomy of the angle structure (glaucoma)
Anatomy of the angle structure (glaucoma)
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Anatomy of the angle structure (glaucoma)

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Anatomy of the angle structure (glaucoma)

  1. 1. Recommended Books for Ophthalmology 1. Vaughan & Asbury’s General Ophthalmology 16th Edition 2004 a LANGE medical book • Parsons’ Diseases of the Eye 19th Edition 2003 Butterworth publication 3. Clinical Ophthalmology by Jack J. Kanski 5th Edition 2003 Butterworth publication
  2. 2. GLAUCOMA Patho-physiology & Detection Dr. Nasir Saeed
  3. 3. Epidemiology of Glaucoma Glaucoma is not a single disease entity,but the result of a group of different mechanisms which cause a loss of retinal ganglion cells. This loss may be acute or episodic, or slowly and relentlessly progressive. Some authors therefore refer to ‘the glaucomas’. The common, connecting feature used to be regarded as the height of the intraocular pressure (IOP), which dominated the understanding of the clinical manifestations to a greater or lesser extent. Although intraocular pressure is frequently raised, it is now regarded as a risk factor, and no longer considered a defining characteristic.
  4. 4. Glaucoma prevalence surveys, by racial groups Location Age PACG (%) POAG (%) Secondary glaucoma Congenital/ Developmental European Baltimore, Md. 40+ 0.31 1.29 0.68 No available Origin Beaver Dam, Wisc. 43-84 0.04 2.1 Not stated Not stated Blue Mountains, Australia 49+ 0.27 3.0 0.15 Nil African Jamaica 35-74 Nil 1.4 0.35 Nil Origin Baltimore, Md. 40+ 0.67 4.74 1.42 Not available Asian Umanaq area, Greenland >40 4.8 1.26 1.00 Nil NW Alaska 40+ 2.65 0.24 Nil Nil Beijing, China 40+ 1.4 0.03 Not stated Not stated Hövsgöl, Mongolia 40+ 1.4 0.5 0.3 Nil Origin
  5. 5. World estimates of glaucoma prevalence Affected Congenital 300 000 POAG 13.5 million PACG 6 million Secondary 2.7 million Glaucoma suspects 105 million (IOP>21 mmHg) Blind 200 000 3 million 2 million ?
  6. 6. RISK FACTORS Age: The prevalence and incidence of PACG increase with age. Although a peak has been claimed, the best evidence suggests that incidence rises continually with age. Attacks of ACG are rare before age 45.
  7. 7.  GENDER • POAG • PACG  Race • Chinese • European • Africans • Japanese • Asians  Refraction • ACG • POAG Genetics Equal Females > Males ACG POAG POAG<ACG NTG ACG<=POAG Hypermetopes Myopes
  8. 8. • Intra-ocular Pressure • Diabetes • Family History • Hypertension • Vascular Spasm
  9. 9. ANATOMY OF THE ANGLE STRUCTURES
  10. 10. Aqueous Humour Produced by the ciliary processes into the posterior chamber • Through the pupil it circulates into the anterior chamber • 90% of it is drained through the trabecular meshwork into the Schlemm’s canal and the epi-scleral venous system (conventional pathway) • 10% of it leave the eye through the uveo-scleral route (un-conventional pathway) into the suprachoroidal space and chained by venous circulation of the ciliary body and sclera
  11. 11. Functions of Aqueous humour  It maintains the shape and internal structure of the eye by sustaining an intraocular pressure higher then atmospheric pressure and helps in maintaining the optical structure.  It carries oxygen and nutrients to the lens and cornea It carries waste products away from the lens and cornea
  12. 12. Aqueous humour production • Produced by the ciliary processes of the ciliary body. Two Mechanisms I- Active secretion • 80% of aqueous is produced by the non pigmented ciliary epithelium as a result of active metabolic process • Involves several enzymatic systems i.e. Na+ - K + ATPase / Carbonic Anhydrase • Na+, K+, Ascrobate, HCO3 • Transported into the posterior chamber • Secretion diminishes by factors which will inhibit active metabolism like drugs, hypoxia, hypothermia • Independent of IOP
  13. 13. Aqueous humour production II- Passive Secretions • 20% • Diffusion to maintain equilibrium between the osmotic pressure and electrical balance on the two sides of the ciliary processes • Ultra-filtration • When the diffusion of water and salt is accelerated by blood pressure (hydrostatic pressure) in the ciliary body The passive secretion is dependent on level of blood pressure in the ciliary body, plasma oncotic pressure and intraocular pressure • Blood Aqueous Barrier • Large molecules such as plasma proteins and cells do not get into the aqueous chambers even when the plasma concentration is very high •Sites of the barrier is tight junctions between the non-pigment ciliary epithelium and their basement membrane
  14. 14. Intra-ocular pressure (IOP) • The circulation of aqueous humour in the eye maintains the IOP • The equilibrium of aqueous formation and outflow rate is of crucial importance • Normally aqueous humour is secreted at a rate of 0.02µl / minute and same amount is drained •The distribution of IOP in general population : 11-21 mm of Hg •Average = 15 mm of Hg • Diurnal variation – High in morning Low in evening • No sex difference by 5 mm of Hg
  15. 15. Determinants of Intraocular Pressure • Rate of aqueous humour formation • Resistance encountered in out flow channels • Level of epi-scleral venous pressure
  16. 16. Factors influencing Intra-Ocular Pressure I- Rate of Aqueous Humour formation Increased by a. Inflammation b. Blood Pressure c. Hypo-osmolarity of plasma Decreased by a. Retinal / Choroidal / Ciliary body detachments b. Drugs B-Blocker Carbonic Anhydrase hulibitors c. Anaesthesia
  17. 17. II- Out flow Resistance Increased by Age Membrane • Pupillary Block Synechia Lens Vitreous • Trabecular Meshwork block Inflammation Cellular debris Steroids Inflammatory exudates Peripheral Iris bowing Peripheral Anterior Synechia Idiopathic
  18. 18. • Outflow Resistance Decreased by • Accommodation • Drugs • Miotics • Prostaglandins • Adrenaline
  19. 19. III- Episcleral Venous Pressure Increased by • Increased CVP • Valsalva • Carotid Cavernous fistula • Hypercarbia •Dysthyroid eye disease •Succinyl – choline • Co-contraction of extra-ocular muscles Decreased by • Hypotension • Decreased carotid blood flow • Decrease CVP
  20. 20. Applied Anatomy of the optic n. head Retinal Nerve fibre layers
  21. 21. Relative positions of nerve fibre layer
  22. 22. Cross Section of the Optic N. Head
  23. 23. Optic Cup & Neuro-retinal rim
  24. 24. Physiological Cup & Neuro-retinal rim
  25. 25. Glaucomatous Damage Retinal Nerve fibre layers Normal
  26. 26. Glaucomatous Damage Abnormal Nerve fibre layers
  27. 27. Abnormal nerve fibre layers
  28. 28. Glaucomatous Damage Optic disc cupping
  29. 29. Bilateral glaucomatous cupping with inferior notching and ‘bayonetting’
  30. 30. Bilateral advanced glaucomatous cupping with nasal displacement of the blood vessels
  31. 31. End – Stage glaucomatous cupping
  32. 32. Clinical Methods for detection and evaluation of glaucoma • IOP Measurements • Gonioscopy • Perimetry Techniques • Advanced Techniques
  33. 33. Measurement of Intraocular Pressure Tonometry Principal • The pressure inside a sphere may be measured directly by canulating it and connecting it to a measuring device. This is called manometry. It is the most accurate method but not practical for routine clinical measurement. • It can also be measured by the • Imbert – Fick Law – Pressure = Force /Area. • The pressure can be measured by measuring the force necessary to flatten a fixed area or by measuring the area flattened by a fixed force. • Also a known force will indent a sphere. In low pressure the indentation will be more and in high pressure the indentation will be less.
  34. 34. Goldmann Applanation Tonometer • Applanation tonometry measures the force applied per unit area. The Goldmann tonometry is a variable force tonometer consisting of a double prism with a diameter of 3.06 mm. It is the most popular and accurate tonometer.
  35. 35. Goldmann applanation tonometer
  36. 36. Fluorescein-stained semicircles seen during tonometry
  37. 37. A- Schiotz tonometer B- Principles of indentation tonometry
  38. 38. • Checking for diurnal changes= phasing • Demonstrating elevation of IOP after pupillary dilation, water drinking • IOP checking in different direction of gaze • Checking for steroid responsiveness • IOP-measurement digitally
  39. 39. Gonioscopy • Visualization of the anterior chamber angle is called Gonioscopy Purposes 1. Diagnostic: to identify abnormal angle structures and to estimate the width of the anterior chamber angle. This is particularly important to classify the open angle and angle closer glaucoma 2. Surgical: to visualize the angle during the procedures such as laser trabeculopasty and goniotomy
  40. 40. Optical Principal • In normal circumstances the angle of anterior chamber can not be visualized because of the total internal reflection Lighter Medium a b c d d c b a Critical Angle Denser Medium
  41. 41. Optical Principal of Gonioscopy
  42. 42. Single Mirror goniolens & Zeiss four mirror goniolens
  43. 43. Swan-Jacob surgical goniolens & Koeppe goniolenses
  44. 44. Normal Anatomy of Angle structure
  45. 45. Schaffer’s Grading System
  46. 46. Abnormal Anterior Chamber Angle
  47. 47. Perimetry • Visual fields ; • An island of vision surrounded by a sea of darkness
  48. 48. • Isopter. An Isopter is a line in the field of vision exhibiting similar visual acuity • Scotoma. Is a defect in the visual field • Absolute • Relative • Positive • Negative • Visible threshold. Is the luminance of the stimulus measured in dB at which it is perceived 50% of times when it is presented statically
  49. 49. Perimetric Principals • Perimetry is a method of evaluating the visual fields • Qualitative Perimetry is a method of detecting a visual field defect and is the first screening phases of glaucoma suspects • Quantitative Perimetry
  50. 50. Visual Fields defects in glaucoma 1. Arcuate scotomas : develop between 100 and 200 of fixation in areas that constitute downward or more commonly, upward extensions from the blind spot (Bjeerrum area) 2. Isolated paracentral scotomas: superior or inferior scotomas may also be found in early glaucoma. 3. A nasal (Roenne) step 4. Ring scotomas 5. Temporal Wedge 6. End Stage fields defects
  51. 51. 1. Arcuate scotomas : develop between 100 and 200 of fixation in areas that constitute downward or more commonly, upward extensions from the blind spot (Bjeerrum area)
  52. 52. Isolated paracentral scotomas: superior or inferior scotomas may also be found in early glaucoma
  53. 53. A nasal (Roenne) step
  54. 54. Temporal Wedge
  55. 55. End Stage fields defects
  56. 56. Advanced Techniques Quantitative Measurements • Digitalized photogrammetry • Confocal scanning laser ophthalmoscope (HRT) • Measurements of ocular blood flow
  57. 57. Digitalized photogrammetry
  58. 58. Confocal scanning laser ophthalmoscope (HRT)
  59. 59. Glaucoma is the second leading cause of worldwide blindness. Early detection and early onset of treatment are the most important factors for preventing progressive glaucoma damage. A comprehensive evaluation of a glaucoma suspect is the key to diagnosis and management.
  60. 60. The aims of assessment are:  To assess the risk factors to determine whether glaucoma is present or likely to develop  To exclude or confirm the alternative diagnosis  To identify the underlying mechanism of damage; so as to select best choice for management  To plan a strategy for management
  61. 61. ASSESSMENT
  62. 62. Presenting Social HISTORY Family Past
  63. 63. VA Gonio OM IOP Exoph EXAMINATION Fundus Ocu surf Cornea Lens Pupils AC
  64. 64. Ocular Examination  Record visual functions  Ocular motility  Exclude any proptosis/exophthalmos  Ocular surface for episcleral blood vessels  Conjunctiva for papillae and follicles  Cornea for size, shape and transparency  Check for corneal thickness
  65. 65. Ocular Examination  Anterior chamber for inflammation, blood, pigment  Check for AC depth, central and peripheral • Convex iris-lens diaphragm • Shallow anterior chamber • Narrow entrance to chamber angle
  66. 66. Ocular Examination Iris for atrophy , rubeosis, trans-illumination defects and pseudoexfoliation Stromal iris atrophy with spiral-like configuration Mid-peripheral iris atrophy Central disc with peripheral band
  67. 67. Ocular Examination  Pupil for size, shape and reaction  Lens for presence, transparency, thickness, position and shape
  68. 68. Ocular Examination    Record intraocular pressure, look for diurnal variations Evaluate IOP for 24 hours if in doubt Use a Goldmann-style applanation tonometer
  69. 69. Ocular Examination Gonioscopy: look for width of the angle, configuration of the iris and chamber, PAS, vessels and iris processes Open angle of normal appearance Schaffer’s grading of angle Trabecular hyperpigmentation - may extend anteriorly (Sampaolesi line) Synechial angle closure Irregular widening of ciliary body band
  70. 70. Ocular Examination Fundoscopy: evaluate optic nerve head and retinal nerve fibre layer use slit lamp indirect lenses and a dilated pupil Look for optic disc size, colour, neuro-retinal rim, disc haemorrhage, vascular pattern, peri-papillary atrophy and cup disc ratio Small dimple central cup Larger and deeper punched-out central cup Cup with sloping temporal wall
  71. 71. Optic disc evaluation
  72. 72. Retinal nerve fibre layer analysis
  73. 73. Investigations Order for a visual field examination with a standard automated perimeter
  74. 74. Investigations HRT OCT GDx
  75. 75. Systemic investigation include Imaging of CNS Evaluation of CVS Haematological profile

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