THE GLAUCOMAS 2

Dr Russell J Watkins

Classification The diagnosis of glaucomatous optic neuropathy is based

on ONH examination, and to some extent, VF analysis All forms of glaucoma are classified into primary &

secondary forms based on Gonioscopic findings Associated ocular and extraocular findings

Major risk factors IOP Vascular risk factors

• Local• Systemic

Race

Classification Associated conditions

Ocular Extraocular

Additional useful clinical data BP, pulse, blood glucose, blood lipids Migraine, cold hands/raynaud’s Thyroid disease, neurological diseases History of blood loss, smoking FOH +ve for visual loss FOH +ve for glaucoma

Classification Primary Congenital Forms

Primary Congenital Glaucoma Primary Infantile Glaucoma Glaucoma associated with congenital

anomalies

Classification Primary Open Angle Glaucomas

Primary juvenile glaucoma Primary open angle glaucoma Normal tension glaucoma Ocular hypertension

Classification Secondary Open Angle Glaucoma

Pseudoexfoliation glaucoma Pigmentary glaucoma Lens-induced OAG Glaucoma associated with intraocular

haemorrhage Uveitic glaucoma et al ++

Classification Primary Angle Closure Glaucomas

Pupillary block mechanism Plateau iris mechanism Chronic and intermittent ACG Malignant glaucoma (some may class this as

secondary)

Classification Secondary Angle Closure Glaucomas

Secondary ACG with pupil block Secondary ACG due to “pulling” of AC

• NVG• Aniridia• Inflammatory membrane• et al++

Primary ACG Multiple pathogeneses Basically acute & chronic forms Defined on the basis of findings on gonioscopy

In acute angle closure, there is iridocorneal apposition that can be reversed

In chronic angle closure, angle closure is irreversible because of PAS

Angle is closed without a discernible cause Medical & surgical management differs with OAG

so identification important

Primary ACG Pupillary block mechanism

Pupil block is present in most cases of acute, intermittent & chronic primary ACG

The flow of aqueous from PC to AC is impeded PC pressure to be > AC Peripheral iris bows forward to contact TM Annular drainage obstruction results IOP can to 50-80 mmHg If this occurs within a few hours, AACG results

Primary ACG Pupillary block mechanism (cont.)

resistance to transpupillary aqueous flow is caused by apposition of posterior iris to anterior lens

Pupil block mechanism may be precipitated during mid-dilatation of the pupil• e.g. reading in poor light, mydriatic drug

use Eye is usually predisposed

• Narrow AC• Hypermetropia/short axial length• Large lens

Primary ACG Plateau iris mechanism

Rare mechanism compared with pupil block Anatomical variation in angle causes block

• Anterior insertion of iris (even as far as scleral spur)

• Ciliary processes displaced anteriorly, pushing iris base anteriorly

Attack occurs if mydriasis

Primary ACG Creeping angle closure mechanism

Iris base “creeps” on to TM forming PAS IOP usually rises when >50% of angle is

occluded More frequent in Asians

Primary ACG Posterior aqueous misdirection mechanism

(malignant glaucoma) Rare; usually seen after intraocular surgery Aqueous misdirected into vitreous because of

anatomical factors Lens-iris complex pushed anteriorly, occluding

angle Narrow AC & hypermetropia are risk factors F>M

Primary ACG Risk factors for primary angle closure

Female +ve FOH Use of sympathomimetics Race: Eskimos, Asians (esp. Mongolians)

Primary angle closure is divided into 3 subtypes AACG IACG CACG

AACG Rapid & excessive increase in IOP due to

circumferential iris apposition to TM Does not resolve spontaneously Pathomechanisms

Usually pupil block Occasionally plateau iris & posterior aqueous

misdirection 1 in 1000 people aged over 40yrs (rarer than

OAG) M<F (1:4)

AACG Patients present with

Haloes around lights Blurred vision Ipsilateral frontal headache Occasionally nausea & vomiting Painful red eye

AACG On examination

Red eye (venous & ciliary injection) VA IOP elevated; often 50-80 mmHg Corneal oedema Shallow or flat AC ±cells & flare Gonio: angle closed 360°

• Peripheral iris pushed forward to contact Schwalbe’s line

• Check fellow eye - usually occludable angle

AACG On examination (cont.)

Pupil mid-dilated with reduced or absent reactivity

Fundoscopy• Fundus may be normal• May be disc oedema with venous

congestion & haemorrhage• There may be glaucomatous excavation• Arterial pulsation with high pressure

IACG Aetiology is similar to AACG but is a milder

manifestation Resolves spontaneously Pathomechanisms as AACG Patients present with mild intermittent

symptoms similar to AACG (esp haloes, frontal headache, episodic blurred vision)

On examination, signs vary according to amount of appositional angle closure Pupil is round & reactive or there may be

APD Optic disc may be normal or atrophic

CACG CACG is permanent synechial closure of any

extent of the angle less that 360° Pathomechanism as previous – probably the end

result of repeated IACG Symptoms

Visual disturbance - transient & intermittent Usually painless, occasional discomfort Occasionally transient haloes if IOP

acutely

CACG Signs

PAS of any degree at gonioscopy IOP elevated to a variable degree VA may be normal ONH damage as OAG “Typical” OAG visual field defects Superimposed IACG or AACG possible

Treatment may be medical or surgical

Post AACG Attack Following an attack of AACG, there may be

Poor vision Patchy iris atrophy Iris torsion Pseudopolycoria Posterior synechiae Poorly or non-reactive pupil Glaukomflecken PAS on gonioscopy Endothelial cell count chronic corneal

oedema

The Occludable Angle High risk of closure by aforementioned

mechanisms Fellow eye of AACG/IACG/CACG IOP elevation may or may not be present

Secondary ACG Pupil block can develop due to

Swollen lens (cataract, trauma) Anterior lens dislocation PS seclusio pupillae & iris bombé Miotic use (lens moves forward, also) IOL-induced (ACL; anterior dislocation of

PCIOL)

Secondary ACG An anterior “pulling” mechanism can obstruct

TM, either by iris tissue or membrane NVG Following trauma or intraocular surgery Inflammatory membrane Aniridia

Secondary ACG A posterior “pushing” mechanism can obstruct TM,

because ciliary body & iris rotate forward Abnormally large lens (phacomorphic glaucoma) Aqueous misdirection following PCIOL insertion Iris/ciliary body cysts & tumours Uveal effusion

• Inflammatory (scleritis, uveitis), increased choroidal venous pressure (PRP, CRVO, scleral buckling), tumour

ROP

What is “IOP”?

Risk Factors for OAG IOP Race Age Gender Myopia FOH of glaucoma OR

visual loss Optic nerve head

‘structure’

Vascular disease Hypotension Hypertension Vasospasm Rheological

abnormalities Disc haemorrhage ?Diabetes mellitus

Cigarette smoking Hypothyroidism

IOP (mmHg)

% of Population Developing Glaucomatous Damage

Rate Of Visual Loss & IOP in POAG

21-25 mmHg

26-30 mmHg

>30 mmHg

14yrs

6yrs

3yrs

Loss of Central Vision & IOP in POAG

<18 mmHg

18-22 mmHg

>22 mmHg

4%

19%

29%

OHT Unknown aetiology & pathomechanism IOP >21mmHg ONH normal VF normal No other risk factors

Definition of OAG “The open angle glaucomas are a group of

chronic, progressive optic neuropathies that have in common characteristic morphological changes at the optic nerve head & retinal nerve fibre layer in the absence of other ocular disease or congenital anomalies. Progressive retinal ganglion cell death & visual field loss are associated with these changes.” European European Glaucoma Society, 1998.Glaucoma Society, 1998.

OAG

Primary open angle glaucoma

Normal tension glaucoma

Ocular hypertension

POAG Unknown aetiology Unknown pathomechanism Asymptomatic until field loss advanced IOP>21mmHg without treatment ONH suffers characteristic damage Visual field shows corresponding damage Gonioscopy shows open angle; not occludable;

no goniodysgenesis

POAG POAG suspect

ONH & VF normal or suspicious Peak IOP >21mmHg but <30mmHg without

treatment IOP difference >4mmHg between the two

eyes Concurrent vascular risk factors POAG in fellow eye AION in fellow eye

NTG Unknown aetiology Unknown pathomechanism though vascular

factors thought to be important Asymptomatic until field loss advanced Peak IOP <21mmHg without treatment (phased) ONH damage as POAG VF damage as POAG; paracentral defects are

more common Gonioscopy: open, unoccludable angle

Nocturnal Hypotension

NTG NTG suspect

Normal or suspicious VF &/or ONH IOP as NTG IOP difference >4mmHg between eyes Vascular risk factors NTG in fellow eye

IOP in NTG Diagnosis of NTG can only be made after IOP

phasing A reduction of IOP of 30% in NTG eyes prevents

progression in 80% of eyes A 30% reduction of IOP in NTG is possible in 50%

of NTG eyes If NTG remains untreated, 50-60% of eyes DO

NOT show progression

NTG & HTG NTG HTG

ONH haemorrhage ++ +

CRVO + ++

NRR notching ++ +

Generalised enlargement of cup + ++

Vascular risk factors ++ +

Female predominance ++ +

Vasospasm & systemic hypotension ++ (+)

NTG & HTG NTG HTG

Diffuse visual field damage + ++

Colour vision changes (+) ++

Contrast sensitivity changes (+) ++

Conjunctival microaneurysms ++ (+)

Silent myocardial ischaemia ++ +

Hearing loss + -

Endothelin abnormalities ++ (+)

IOP Mechanic

al damage

Perfusion pressure

Blood pressure

Vascular resistance

Blood flow

ONH

Autoregulation

IOPPerfusion

Rheology

Other factors

Structural factors

2° OAG Elevated IOP causing progressive typical

glaucomatous damage to ONH & VF caused by ocular or extraocular disease(s) or drugs Pseudoexfoliation syndrome Pigmentary glaucoma Phacolytic glaucoma Ghost cell glaucoma Uveitic glaucoma Glaucoma due to intraocular tumours Glaucoma associated with retinal detachment

2° OAG [Classification continued]

Glaucoma secondary to ocular trauma Glaucoma due to corticosteroid treatment Glaucoma due to ocular surgery & laser Glaucoma caused by increased episcleral

venous pressure

2° OAG Pseudoexfoliation glaucoma

Pseudoexfoliative material = abnormal fibrillo-granular protein; accumulates in TM

Syndrome also involves pigment accumulation in TM

Similar material has been identified at extraocular sites

Aqueous outflow Onset usually after age 60yrs

2° OAG Pseudoexfoliation glaucoma (cont.)

IOP >21mmHg, often in the 40s ONH & VF loss as in POAG Dandruff-like material on pupil margin &

anterior lens capsule Pupillary collarette appears motheaten Often associated with NS, narrow angle,

phacodonesis Pigment deposition anterior to Schwalbe’s line

is termed Sampaolesi’s line

2° OAG Pigmentary glaucoma

Melanin granules accumulate in the TM aqueous outflow

“Reverse pupillary block” theory• Iris acts as valve• AC IOP > PC IOP pushing peripheral iris

membrane posteriorly• Melanin granules released because iris rubs

on zonules

2° OAG Pigmentary glaucoma (cont.)

Onset typically third - fifth decades (i.e. under 40!) 1-2% of the total glaucoma cases White myopic males esp Unilateral or bilateral IOP can rise acutely ACG symptoms IOP usually >21mmHg with large variations esp. after

exercise, blinking, mydriasis Deep AC, iris transillumination, pigmented TM,

Schwalbe’s line, iris surface, Krukenberg’s spindle

2° OAG Lens induced open angle glaucoma

3 mechanisms• Phacolytic• Traumatic• Phacoanaphylactic

Age of onset depends on pathomechanism Often painful with inflammatory response IOP >21mmHg Injured lens or cataract; AAU; phakic state of

fellow eye

2° OAG Ghost cell glaucoma

Follows intraocular haemorrhage• Anterior chamber• Vitreous chamber

Effete ghost cells are more rigid than viable RBCs & block TM

Often painful TM can also be blocked following hyphaema

2° OAG Uveitic glaucoma

Anterior & intermediate uveitides• JCA, FUS, Posner-Schlossman syndrome,

HSV, VZV, sarcoidosis, Behçet’s disease, sympathetic ophthalmia, pars planitis

TM blocked by oedema, inflammatory cells & debris, scarring, neovascularisation

Pupil block 2° to PS can also form Onset depends on pathomechanism

2° OAG Glaucoma due to intraocular tumours

Aqueous outflow due to primary or metastatic anterior segment tumour

TM may be compressed or invaded by tumour Also tumour related inflammation, tumour

necrosis, haemorrhage & pigment dispersion Secondary ACG may also develop Onset & clinical picture highly variable

2° OAG Glaucoma associated with retinal detachment

RD usually associated with lower IOP TM can be blocked by proliferative processes,

pigment, scarring, inflammation

2° OAG OAG due to ocular trauma

Several mechanisms• Open angle & closed angle mechanisms

Trauma can cause• Scarring, inflammation, obstruction by RBC

& debris, release of lens proteins, angle recession

Varies from painful & red to asymptomatic IOP can be normal at presentation & climb

slowly over the years

2° OAG Corticosteroid induced OAG

TIGR gene implicated Tendency in myopes, diabetics & POAG Blockage of TM by mucopolysaccharide with

topical steroid Increased aqueous production with systemic

steroids IOP elevation is usually reversible on cessation

of steroid

2° OAG OAG secondary to intraocular surgery & laser

Pigmentary loss, lens material, haemorrhage, inflammation & trauma are possible mechanisms

Alternative pathomechanisms are• Viscoelastic materials, vitreous in AC, prostaglandin

release (IOP spike transient)• IOP transient spike following YAG capsulotomy, YAG

iridotomy, ALT• Macrophages take up silicone oil & block TM• ACIOL can induce chronic uveitis & bleeding of iris

root

2° OAG Glaucoma secondary to increased episcleral

venous pressure Reduced aqueous outflow via schlemm’s canal Episcleral, orbital & general causes

• Dural shunts, toxic or thermal damage to episcleral veins, TED, retrobulbar orbital tumour, AV fistula, Sturge-Weber syndrome et al++

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