3. Introduction
Primary open-angle glaucoma (POAG)
considered as a:
Chronic, progressive, anterior optic neuropathy
leading to damage of retinal ganglion cells and
optic nerve with corresponding visual field
changes
3
4. Characterised by
Glaucomatous optic nerve damage
Visual field loss
Open angles
No obvious causative ocular or systemic
conditions
IOP may be elevated above statistically
‘normal’ range, reflecting reduced aqueous
humor outflow facility
4
5. Epidemiology: The POAG
Burden
POAG: most common form of glaucoma
global prevalence of glaucoma was 3.54% with POAG
prevalence being 3.05%
Incidence of POAG 2.4 million persons per year
Blindness prevalence for all types of glaucoma was >8million
with 4 million caused by POAG
5
6. Prevalence:
Western Europe / United States: 0.5–1%
( above age 40)
Baltimore eye survey: 1.29%
(whites),4.3%(black)
6
7. POAG: Epidemiology
Nepal blindness survey(1981) reported glaucoma
related blindness to account for 3.2% of total blindness
in Nepal
Another study from 2006-2010 in 50+ age group
reported it to be 4% of total blindness
8
8. Bhaktapur Glaucoma study revealed an
incidence of 1.80( age and sex standardized)
and POAG of 1.26 accounting for 685 of total
glaucoma patients(2012)
POAG is more common in males, Gurung
community(2.05x) and was associated with HTN
and DM(2013)
9
10. Demographic risk factors
Race(African, caribbean,
hispanic,chinese,asian )
Age: increases with age
Gender
Family history
20–25% of POAG
13% in monozygotic and dizygotic twin
25% of the siblings of patients with POAG
Socioecomonic factors
11
13. GENETICS OF POAG
GENE LOCI INHERITANCE AGE OF ONSET
GLC1A (Myocilin) 1q23-25 DOMINANT JUVENILE/ADUL
T
GLC1B 2 cen-q13 DOMINANT ADULT
GLC1C 3q21-21 DOMINANT ADULT
GLC 1D 8 q23 DOMINANT ADULT
GLC1E
(Optineurin)
10q15-14 DOMINANT ADULT
POAG/NTG
GLC1F 7q35 DOMINANT ADULT
Phenotypic expression 3% for GLC1A, 5% GLC1E, others very low
14
14. Genetic investigation done if
1. 3 or more first degree relatives from 2
generations are affected
2. research purpose
15
15. Pathophysiology
1. Mechanism(s) of IOP elevation
i. Diminished aqueous humor outflow
facility
ii. Altered corticosteroid metabolism
iii. Dysfunctional adrenergic control
iv. Abnormal immunologic processes
v. Oxidative damage
vi. Other toxic influences
2. Mechanism(s) of progressive optic nerve
16
17. i.Diminished aqueous humor outflow
facility
Site of resistance : Juxtacanalicular tissue
Theories
Obstruction of TM by foreign material
Loss of trabecular endothelial cells
Reduction in pore density and size in inner
wall endothelium of Schlemm’s canal
Loss of giant vacuoles
Loss of normal phagocytic activity
Disturbance of neurologic feedback
mechanisms
18
18. PATHOPHYSIOLOGY CONTD.
ii.Altered corticosteroid metabolism.
1. Increased plasma levels of cortisol
2. Increased suppression of plasma cortisol with
different doses of exogenous dexamethasone
3. Continued suppression of plasma cortisol by
dexamethasone despite concomitant administration
of phenytoin
4. Disturbed pituitary adrenal axis function
5. Increased inhibition of mitogen –stimulated
lymphocyte transformation by glucocorticoids
19
19. Researchers postulated that endogenous
corticosteroids affects trabecular function
by
altering PG metabolism
GAG catabolism
released of lysosomal enzymes
synthesis of cyclic adenosine
monophosphate
20
20. PATOPHYSIOLOGY CONTD.
iii. Dysfunctional adrenergic control
Patients with POAG had:
1. A greater IOP reduction after the administration
of topical epinephrine;
2. A greater response to epinephrine or
theophylline in inhibiting mitogen stimulated
lymphocyte transformation;.
21
21. PATHOPHYSIOLOGY CONTD.
iv. Abnormal immunologic process
Increased level of gamma globulin and plasma
cells found in the TM of patient with POAG.
High prevalence of antinuclear antibodies.
.
22
22. v. Oxidative damage
TM cells contain Glutathione which may protect
endothelial cells from effect of H2O2 and other
reactive oxygen molecules
vi.Other toxic influences
TGF β₂ involvement, plasminogen activator
inhibitor
23
23. Mechanisms of Glaucomatous
optic neuropathy
What is the primary site of glaucomatous
injury?
What factors contribute to ganglion/axonal
injury?
Precisely how do ganglion cells die?
24
25. Primary site
ONH itself – specifically sclera lamina of
ONH
Histological studies ON cupping includes
the loss of all three elements of the disc –
axons, blood vessels and glial cells
Inner retina : damage to retinal ganglion cell
(RGC) and astroglial populations.
26
26. What Injures Ganglion Cells?
Ganglion Cell Susceptibility
Intraocular pressure level
Vascular nutrition of the optic disc
neurotoxicity
How Do Ganglion Cells Die? “ Apoptosis ”
27
27. PATHOGENESIS : GLAUCOMA
Elevated IOP can either lead to
Direct Mechanical compression
Vascular perfusion of optic nerve head
28
34. CLINICAL FEATURES:
SYMPTOMS
Asymptomatic until significant visual field loss
has occurred
Asymmetric progression
Mild headache and eyeache
Reading and close work increasing difficulty
frequent change in presbyopic glasses
Delayed dark adaptation
Haloes may be noted, if there is a sudden severe
rise of IOP, due to corneal edema
35
35. Past medical and ocular history
Surgical history
Family history
Current medication history
Social history
Allergic history
36
36. CLINICAL FEATURES:SIGNS
Early phase : Normal anterior segment findings
Late stage: Sluggish pupillary reflex(APD±) and
minimal corneal haziness
OPTIC DISC CHANGES:
1. Specific signs:
Optic disc cupping
Vertical elongation of cup
Large optic cup (CDR 0.7 or more)ISNT rule not obeyed
Asymmetry of optic cup (difference of CDR 0.2 or more)
Progressive enlargement of optic cup
Focal signs:
Notching of rim (NRR ), Regional pallor, Splinter hemorrhage,
Nerve fiber layer thinning
37
37. CLINICAL FEATURES:SIGNS
2. Less specific signs
“Lamellar dot” sign
Nasalization of vessels
Peripapillary crescent
Baring of circumlinear vessels
38
39. USE OF 24 HOUR MONITORING OF
IOP
Diagnosis of POAG
Explaining progressive damage despite
apparent good pressure control
Evaluating efficacy of therapy
Distinguishing NTG from POAG.
40
41. CLINICAL FEATURES: SIGNS
GONIOSCOPY
Open angle, grossly normal
More iris processes, high insertion of iris root,
more trabecular pigmentation
Greater than normal degree of segmentation in
the pigmentation of the meshwork
to rule out angle-closure or secondary causes of
IOP elevation, such as angle recession,
pigmentary glaucoma
42
42. VISUAL FIELD ABNORMALITIES
Central visual acuity normal.
Peripheral field loss progressive and finally
involves central field.
Subtle measures of visual dysfunction e.g.
contrast sensitivity, color vision and motion
perception are useful early indicators.
43
51. TREATMENT: WHEN TO
TREAT?
Triad of visual field loss, optic nerve cupping, and
elevated IOP, or is at high risk of developing them
Progressive cupping without detectable visual field
loss
visual field loss
Episodes of corneal edema caused by elevated
IOP
A vascular occlusion associated with increased IOP
Asymmetric POAG
59
52. Management
Options:
Medical
Laser
Surgery
Aim:
• To prevent Nerve fibre loss
• To prevent any further visual field deterioration
• To retain the quality of life of the Patient
60
53. MEDICAL THERAPY
First line: prostaglandin analogues or nonselective
β-blocker(MONOTHERAPY)
65
54. For typical glaucoma patient, 2 or 3 medications
would be maximum suggested before resorting
to laser or incisional surgery
66
55. MEDICAL THERAPY
Failure:
Inadequate control of IOP
Progressive visual field loss or optic nerve cupping
Appearance of an optic nerve hemorrhage
Intolerable side effects of medication
Demonstrated (or admitted) poor compliance with
therapy
67
56. SURGERY
medical treatment and laser surgery are
inadequate to control POAG
Controls IOP in approximately 80–90% of
patients
68
57. PROGNOSIS
Lifetime chance of blindness in both eye is 5-10%
Avg. period from diagnosis to death is ~15 yrs
Determined by advanced damage at diagnosis, non
compliance, ethnic origin
69
59. Glaucoma Suspects
Type I
Normal intraocular pressure, no damage
Strong family history of glaucoma
Retinal vascular occlusion
Exfoliative syndrome
Angle recession
Pigmentary dispersion syndrome
Narrow angles
Uveitis
History of halos
71
60. Type 2
Normal intraocular pressure, possible
damage
Thin corneas
Suspicious optic disc
Suspicious nerve fiber layer defects
Suspicious visual field
Reduced psychophysical function
72
62. TYPE IV
High intraocular pressure, possible damage
Peripheral anterior synechiae and narrow
angles
Notch or local rim narrowing of optic nerve
Early arcuate scotoma or paracentral scotoma
74
63. Follow up
• Every 6-12 months
• Visual field 6-18 months
• Tonometry and ophthalmoscopy every 1 or 2
years up to age 60, with increasing frequency
over age 60
76
69. OCULAR HYPERTENSION
Treatment should be reserved for
patients who demonstrate early damage
Who are thought to be at high risk for developing
glaucoma
82
70. PROGRESSION TO POAG
Prospectively proven risk factors
Thin corneas (<535 microns)
Elevated intraocular pressures
Increasing age
Vertical cupping of optic nerve (>0.6)
Increased pattern standard deviation on threshold perimetry
83
71. INDICATIONS FOR
TREATMENT
If IOP is 30 mmHg or greater
IOP in mid-to-upper 20s + one or more risk factors
one-eyed patient
young patient
84
72. Unreliable visual fields / optic disc assessment
Patient who is content with treatment
Patient who desires treatment
Vascular occlusion in either eye
85
74. NORMAL TENSION
GLAUCOMA
Typical glaucomatous optic disc cupping
visual field loss
normal IOP
open angles
absence of any contributing ocular or specific
systemic disorders
87
78. PATHOGENESIS OF NTG
CONTD.
Sleep disorders associated risk factor
Mutations in optineurin gene
E50K mutation in optineurin gene
more severe disease &progressive course than NTG
patients without this mutation
91
80. IOP higher than 15 mmHg twice likely to progress
over 2 yrs
Wide variation in 24-hour IOP and with disc
hemorrhage greater risk of progression
Most cases of normal-tension glaucoma are
detected because of optic disc cupping
93
81. SUBGROUPS OF NTG
Senile sclerotic group with shallow, pale ,sloping
of NRR ( In older with vascular disease)
Focal ischemic group with deep ,focal notching in
NRR
94
82. EXAMINATION :NTG
Ocular examination should include:
IOP measurement at different times of day & evening,in
sitting & supine position
Ausculation & palpation of carotid A. reveal obstructive
disease
95
85. Indication for neuroimaging
Age < 50 yrs
New onset or increase of headcahe
Localizing neuro symptoms
Color vision abnormalities
Highly asymmetric cupping
NRR pallor
Lack of disc and visual field correlation
98
87. TREATMENT
Lowering IOP is main thrust of treatment
IOP to be lowered by 30% which significantly
reduced incidence of future progression
Disorders such as anemia, arrhythmia, and
congestive heart failure should be treated to
prevent ischemia of optic nerve
101
88. If untreated pressures are in high teens, then
a target of 15 mmHg or less is reasonable
If untreated pressures are in mid teens, then
one should aim for pressures in the 10–12
mmHg range
TREATMENT OF NTG CONTD.
102
89. Medical therapy
Dipivefrinsuperior to timolol in preventing
visual field progression despite similar pressure-
lowering effects
Brimonidineneuroprotective effects
independent of its pressure-lowering ability
104
90. Betaxolol compared with timolol, has been
shown to have some direct
neuroprotective characteristics, as well
as to produce increased blood circulation
around optic nerve
105
91. Dorzolamide improve blood flow velocity in
vicinity of optic nerve
Laser trabeculoplasty limited benefit in
normal-tension glaucoma but may be worth
trying in patients who are reluctant to undergo,
or are high-risk candidates for surgical
intervention
106
92. Trabeculectomy lowers pressure and
seems to slow but not necessarily stop
progression of condition
Patients who have had successful
trabeculectomy seem to do better if they
also receive systemic calcium channel
blocking agents
107
93. RECENT MODALITIES:TREATMENT
OF NTG
serotonin antagonist :Naftidrofuryl improves
visual acuity and visual field performance in normal-
tension glaucoma.
Calcium channel blocking agents increase
optic nerve function and improve blood flow to
nerve
Nilvadipine, a calcium channel blocker, improved
blood flow around optic nerve in patients with
normal-tension glaucoma
108
94. Systemic calcium channel blockers help in
improvement in contrast sensitivity &
improvement of indirect measures of blood flow
Nimodipine-like agent, Brovincamine shows
prevention of visual field progression
109
95. Risk factors for progression
diabetes mellitus
positive family history
female gender
disc hemorrhage
increased systolic blood pressure
history of systemic hemorrhage
110
96. BIBLIOGRAPHY
Diagnosis & therapy of glaucomas,8th edition
Becker-Shaffer’s
Glaucoma ,section 10
BCSC,AAO,2016-2017
Clinical ophthalmology,7th edition
Jack. J. Kanski
Myron yanoff & jay S Duker ophthalmology(5th
edition)
Text book of Glaucoma,4th edition
M. Bruce Shields
111
Other names
;idiopathic open angle glaucoma, chronic simple glaucoma, open angle glaucoma with damage
According to WHO..Glaucoma was theoretically calculated to account 12.3% of cases of blindness so is second leading cause of blindness worldwide
APEDS=andra pradesh eye disease study,ACES=Aravind comprehensive eye survey,CGS=CHENNAI GLAUCOMA STUDY in 2013
Baltomore eye survey showed 11% more in >80 years and collaborative initial glaucoma treatment study CIGTS showed 7 times more likely to progress visual field defects..although metanalysis show higher prevalence in male few studies show no differneces and others show higher prevalence in females..
Baltimore eye survey showed 3.7 fold increased poag in indiviual’s sibling
Important moldifiable risk factors for glaucoma but not needed for diagnosis.glaucomatous damage is supported coz of iop as visual loss more severe with high iop and lowering iop decreases rate ofd visual field lossbut 30-40% had glaucoma even iop was less than 22 mm hg. 2-4 times higher for high myopia>6diopter 5 times risk of poag in east asian popn...hispanic people in los angeles showed ppa in 83 % of glaucomatous eyes…thinner corneas are biomarker for disease susceptibility and dz progression
5% yearly increase of glaucoma from DM.but ohts showed reduced risk of developing glauc oma in dm pt.baltimotre eye survey showed lower risk of glaucoma in young and higher in older due to better perfusion of on and a/e of microcirculation of onb
MYOC gene coding for protein myocillin found in TM..OPTN gene coding for optineurin..if single family member develops glaucoma prior to age 35 yrs,the chances of mutation in myocillin gene may be 33%
Diminished outflow by increased sensitivity to adrenergic agonists
(Ocular hypertensive subjects who demonstrated a fall in IOP greater than 5mm Hg after topical epinephrine administration had a higher rate of developing visual field loss)
All orthograde and retrograde intra-axonal transport disrupted
All orthograde and retrograde intra-axonal transport disrupted
coats of eye can withstand fairly high IOP except at lamina cribrosa, the fenestrated region through which optic nerve fibres enter eye. Here nerve fibres are supported by glial tissue and have to bend over edge of disc
significant backward displacement and compaction of laminar plates narrows openings through which axons pass, directly damaging nerve fibre bundles
.. Raised IOP mechanical pressure on lamina cribosa altering capillary blood flow and decreasing axoplasmic flow in initial stages.
Brain-derived neurotrophic factor (BDNF) is retrogradely transported from retinal ganglion cell axonal terminals to cell bodies of neurons and that trophic factors are essential to RGC survival.
A substantial rise in IOP can also decrease capillary blood flow due to mechanical compression of vessels at lamina cribosa.
A fall in perfusion pressure at optic disc can be caused by systemic factors such as hypotension, vasospasm and acute blood loss.
The perfusion of optic nerve head may be affected because of lack of adequate autoregulatory mechanism.
Asymptomatic until significant visual field loss has occurred(Damage occurs gradually and fixation is involved late in course of disease)
Peak in the afternoon or evening or follow no consistence pattern.
Diurnal IOP measurement useful (24 hour monitoring >6mm Hg difference is significant)
Circadian rhythm of IOP rises most in the early hours of the morning;
IOP also rises with supine posture
A difference between the 2 eyes of ≥3 mm Hg greater suspicion of glaucoma.
Pachymetry affects applanation tonometry values
Marked differences in IOPs between the two eyes should raise suspicion of exfoliative syndrome or another form of secondary glaucoma.
ANGLE MAY BE NARROW BUT there can be no peripheral anterior synechiae (unless caused by prior laser treatment or surgery), no apposition between the iris and the trabecular meshwork, and no developmental abnormalities of the angle
ANGLE MAY BE NARROW BUT there can be no peripheral anterior synechiae (unless caused by prior laser treatment or surgery), no apposition between the iris and the trabecular meshwork, and no developmental abnormalities of the angle
Superior paracentral scotoma
Both 6 and 7.
Now criterion standard for every baseline examination in patients who are at risk for/suspected of having glaucoma.
or blue-yellow perimetry):
SWAP detects visual field loss earlier than Humphrey visual field test
SWAP detects visual field loss earlier than Humphrey visual field test
As in SWAP, helpful to detect nerve fiber layer loss at an earlier stage thereby screening out more people who are currently misdiagnosed as having only OHT instead of early POAG
(also called frequency doubling technology or FDT ):Newer technology that projects an alternating pattern of gridlines onto a screen and stimulates specific neurons that may be damaged early in OHT or POAG
provides a permanent record of appearance of optic disc
This can allow identification of nerve fiber layer defects that are characteristic of glaucomatous damage.
Photographs taken over a period of time may be compared to track the progression of glaucoma.
The retinal nerve fiber layer sometimes can be imaged on high-contrast black and white film using red-free techniques.
provides quantitative information about the cup, neuroretinal rim, and contour of nerve fiber layer
This can allow identification of nerve fiber layer defects that are characteristic of glaucomatous damage.
Photographs taken over a period of time may be compared to track the progression of glaucoma.
The retinal nerve fiber layer sometimes can be imaged on high-contrast black and white film using red-free techniques.
This can allow identification of nerve fiber layer defects that are characteristic of glaucomatous damage.
Photographs taken over a period of time may be compared to track the progression of glaucoma.
The retinal nerve fiber layer sometimes can be imaged on high-contrast black and white film using red-free techniques.
estimates of peripapillary nerve fiber layer thickness
This can allow identification of nerve fiber layer defects that are characteristic of glaucomatous damage.
Photographs taken over a period of time may be compared to track the progression of glaucoma.
The retinal nerve fiber layer sometimes can be imaged on high-contrast black and white film using red-free techniques.
Asymmetric POAG the other eye usually is treated aggressively because it has at least a 40% chance of developing visual field loss over a 5-year period.
In Collaborative initial glaucoma treatment study(CIGTS),target IOP was set for each patient based on following formula:
[1-(reference IOP+CIGTS Visual field score)/100 X reference IOP]
Where,Reference IOP:Mean of 6 separate IOP measure taken in course of 2 baseline visits
Visual fields score:Measure of VF score from atleast 2 Humphrey 24-2 taken during 2 baseline visits
Minimum lowering achieved in CIGTS was 35%,led to satisfactory outcome with 10-12% progressing over 5 yr follow up
Filtering surgery achieve best lowering of IOP
more effective than medical therapy in preserving visual field but is associated with a greater loss of visual acuity and a higher incidence of cataract
Should prescribe safest drug or drugs for patient in lowest concentration necessary to control IOP at desired level.. carbonic anhydrase inhibitor, α-agonist
If two or more filtering surgeries have failed despite antifibrosis agents or there is a high likelihood of failure after a single filtering operation fails, a tube-shunt (glaucoma drainage) device such as a Molteno,
Baerveldt, or Ahmed implant can be used.. If one drainage procedure fails to control IOP or if risk factors for failure are high (e.g., black African ancestry, youth, secondary glaucoma), many ophthalmologists repeat filtering surgery with an inhibitor of wound healing, such as 5-fluorouracil or mitomycin C
Open angle by gonioscopy and one of the following in 1 eye
Suggest treatment,can initiate or monitor closely,monitor iop and onh
If additional risk factors exist (elevated IOP, thin corneas, black), then more frequent examinations
Iop elevated above 21 mm hg in absence of optic nerve,retinal nerve fibre layer or visual field defect
Black African descent>Mixed race>whites in same age groups…prevalence is 8 times more than poag
Iop reduced by 20%..Study done for 5 years
Doubled when african americans were considereed;;16% in observation group and 8.4% in treated group
Risk of developing glaucoma was increased by 10% for every mm Hg increase in iop
Risk increase by 32% for each 0.1 increment in vertical CDR
detect optic nerve functional damage and anatomic damage early. e.g. parapapillary atrophy, as well as larger vertical cup-to-disc ratio, and small neural retinal rim area-to-disc area ratio are predictive.
STARR II RISK CALCULATOR
Abnormalities in optic nerve with scanning laser ophthalmoscope
Pseudoexfoliation
If IOP is 30 mmHg or greater, noting that prevalence of glaucoma at this pressure level is 11–29%
A patient who is content with treatment initiated by another physician and who is tolerating medication well
B-adrenergic antagonists,brimonidine,latanoprost,topical CAI..monotherapy with maximun 2 medications..if not tolerated evem ALT or SLT
variant of POAG in which the optic discs demonstrate greater vulnerability to the effects of IOP
.. slowed parapapillary, choroidal, and retinal circulations; peripheral vasospasm,
Abnormal immunoproteins such as anti-Ro/SS-A positivity and heat shock protein antibodies indicating a possible autoimmune mechanism.
Elevated plasma C-reactive protein levels as an indicator of vascular inflammation have been found in normal-tension glaucoma patients compared to normal.
Polymorphisms in OPA1 gene mutations of which have been associated with dominant optic atrophy : normal-tension glaucoma may be a variant of dominant optic atrophy
resemble POAG except for absence of elevated IOP.
IOPs cluster at upper end of normal range; that is, IOPs are more often 18 or 19 mmHg than 10 or 11 mmHg.
Wide diurnal and postural fluctuations
2 groups based on disc appearance:
ONH larger,rim thinner especially inf. And inferotemporally,PPA more prevalent,RNFL defect more localized and closer to macula
Abnormalities in local optic nerve or peripapillary blood flow in normal-tension glaucoma as measured by color doppler imaging,laser doppler flowmetry,fluorecein angiography,pulsatile ocular blood flow measurement
Abnormalities on FFA includes diffuse & focal hypofluorescence of disc & abnormal transit time
Pt. shows increased resistance of ophthalmic A. compared with OAG measured by Doppler velocity
MEDICAL&NEUROLOGICAL evaluation should be considered
Alpha2 agonist brimonidine,CAI main drugs..as PG analogs decrease ocular blood flow and b blocker decrease systemic nocturnal pressure drop..nut betaxolol can be used
Traditional medications such as miotics and B-blocking agents may not produce striking reductions of IOP because baseline pressure levels are often 15–19 mmHg. In one study, these agents only produced an average 12–13% reduction
(timolol decreases IOP more)
best way to achieve IOPs of 6–10 mmHg is through a full-thickness filtering procedure or through a guarded procedure such as trabeculectomy augmented by antifibrosis therapy in perioperative period