Glaucomatous Optic Nerve Damage

Slide 1 · Glaucomatous

Optic Nerve Damage

Mechanisms, morphology, and clinicopathologic interpretation

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Link aqueous outflow abnormalities to elevated intraocular pressure.

Explain why pressure and optic neuropathy are not interchangeable.

Recognize retinal and optic-nerve morphology, including age-dependent sequelae.

Distinguish glaucomatous changes from selected optic neuropathies.

Aqueous outflow

Ganglion-cell injury

Morphologic pattern

Slide 3 · Glaucoma is defined by characteristic injury

Distinctive optic nerve cup and visual-field changes.

Intraocular pressure is usually elevated, but not invariably.

The damage phenotype is more specific than a pressure reading alone.

Optic cup

Visual field

IOP often ↑

Slide 4 · The optic nerve is a central nervous system tract

The optic nerve consists of neuronal axons carrying visual information.

Meningeal coverings surround it, with cerebrospinal fluid around the nerve.

Its pathology therefore shares important features with central nervous system injury.

Schematic • optic nerve and meningeal sheath

Dura / sheath

Optic nerve

Axons

Optic axons form a sensory tract invested by meninges.

Slide 5 · Ganglion cells connect retina to optic nerve

Retinal ganglion-cell bodies are within the inner retina.

Their axons form the retinal nerve-fiber layer.

Axons converge at the optic disc and populate the optic nerve.

Schematic • selective inner retinal loss

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Anatomic compartments

Ganglion-cell axons

The nerve-fiber layer contains ganglion-cell axons.

Slide 6 · Structural loss produces functional consequences

Loss of ganglion cells removes retinal output neurons.

Loss of their axons reduces tissue within the nerve-fiber layer and optic nerve.

Glaucoma is associated with characteristic visual-field changes.

Ganglion-cell loss

Axonal / fiber loss

Optic nerve change

Visual-field deficit

Slide 7 · Pressure is a major contributor, not a definition

Intraocular pressure

Neuronal injury

Important exposure

Often elevated in glaucoma

Not sufficient alone

Ganglion-cell / axon loss

Cupping + field change

Variable susceptibility

Slide 8 · Pressure-related damage has a common endpoint

Distinct outflow defects can elevate intraocular pressure.

Prolonged exposure is linked with retinal ganglion-cell and optic-nerve loss.

Different initiating mechanisms can converge on the same morphologic phenotype.

Impaired aqueous egress

Pressure elevation

Susceptible axons

Atrophy / cupping

Slide 9 · Aqueous humor is produced in the ciliary body

Aqueous humor originates in the ciliary body.

It first enters the posterior chamber behind the iris.

Production continues even when drainage is obstructed.

Ciliary body

Posterior chamber

Anterior chamber

Slide 10 · Aqueous humor moves through the pupil

Fluid passes from posterior chamber through the pupillary aperture.

It subsequently occupies the anterior chamber.

The pupillary passage can become a point of obstruction in predisposed eyes.

Posterior chamber

Pupil

Anterior chamber

Slide 11 · The trabecular route is the major outflow path

Most aqueous humor exits through the trabecular meshwork.

The meshwork lies at the iridocorneal angle.

Aqueous passes toward Schlemm canal; Minor routes also exist.

Anterior chamber

Trabecular meshwork

Schlemm canal

Slide 12 · Aqueous outflow obstruction elevates pressure

Resistance within the major drainage route impairs egress.

Ongoing aqueous formation sustains a pressure load when outflow falls.

The obstruction site distinguishes major glaucoma mechanisms.

Aqueous formation

Reduced outflow

Higher intraocular pressure

Optic nerve exposure

Slide 13 · Open-angle and angle-closure are mechanistic classes

Open-angle

Angle-closure

Angle anatomically accessible

Outflow resistance increased

Primary / secondary

Iris obstructs angle

Physical egress block

Primary / secondary

Slide 14 · Open-angle glaucoma retains angle access

Aqueous humor can reach the trabecular meshwork.

The major impediment is increased resistance in the open drainage angle.

This distinguishes resistance from anatomic closure of the angle.

Schematic • iridocorneal drainage angle

Trabecular

Meshwork

Cornea

Iris

Angle patent

Aqueous can approach the meshwork

Slide 15 · Primary open-angle disease may look subtle anteriorly

The anterior-chamber angle remains open.

Few structural changes may be apparent in the anterior segment.

The precise cause of increased outflow resistance is unknown.

Schematic • iridocorneal drainage angle

Trabecular

Meshwork

Cornea

Iris

Angle patent

Aqueous can approach the meshwork

Slide 16 · Genetic associations do not equal one mechanism

Genetic factors are suspected in primary open-angle glaucoma.

The source reports genome-wide associations involving 40 genes.

The findings do not establish one universal mechanism for impaired aqueous egress.

Genetic

Associations

Loci

Many genes

Unknown pathway

Association does not establish a single causal outflow defect

Slide 17 · Pseudoexfoliation can obstruct open-angle drainage

Fibrillar material is deposited throughout the anterior segment.

The condition is described as the commonest secondary open-angle glaucoma type.

Deposits may also occur around connective-tissue vessels and in other organs.

Fibrillar deposits

Anterior segment

Outflow resistance

Pressure elevation

Slide 18 · Lens proteins may clog the trabecular meshwork

Dissolution of lens material releases high-molecular-weight proteins.

The resulting particulate load may impede trabecular drainage.

This source-defined mechanism is called phacolytic glaucoma.

Lens dissolution

Protein material

Trabecular clogging

Secondary open-angle

Slide 19 · Senescent erythrocytes can obstruct the angle

Following ocular trauma, senescent red cells may remain in the eye.

These cells can block the trabecular outflow apparatus despite an open angle.

The named entity is ghost-cell glaucoma.

Ocular trauma

Senescent red cells

Meshwork obstruction

Ghost-cell glaucoma

Slide 20 · Iris pigment can become outflow debris

Pigment granules arise from the iris pigment epithelium.

Pigment can accumulate within trabecular drainage structures.

The resulting secondary open-angle process is pigmentary glaucoma.

Iris pigment

Released granules

Meshwork clogging

Pressure elevation

Slide 21 · Tumor debris can impair open-angle egress

Necrotic tumor material may enter the aqueous compartment.

This particulate load can obstruct trabecular drainage.

The text names melanolytic glaucoma as one example.

Tumor necrosis

Particulate debris

Trabecular obstruction

Melanolytic glaucoma

Slide 22 · Elevated episcleral venous pressure impedes drainage

Increased pressure in the episcleral venous system can elevate intraocular pressure.

The iridocorneal angle remains anatomically open.

Examples include Sturge–Weber vascular malformations and carotid–cavernous fistula.

Venous pressure rises

Aqueous exit impaired

Intraocular pressure rises

Slide 23 · Secondary open-angle causes have different substrates

Trabecular obstruction

Downstream pressure

Pseudoexfoliation material

Lens proteins / ghost cells

Pigment / tumor debris

High episcleral venous pressure

Vascular malformations

Carotid–cavernous fistula

Slide 24 · Angle closure physically blocks the main exit

The peripheral iris obstructs the trabecular meshwork.

Aqueous cannot freely access the major outflow route.

The distinction from open-angle glaucoma is anatomical, not merely pressure magnitude.

Schematic • iridocorneal drainage angle

Trabecular

Meshwork

Cornea

Iris

Angle occluded

Iris contacts the drainage region

Slide 25 · Shallow chambers predispose to primary angle closure

Primary angle closure commonly develops in anatomically shallow anterior chambers.

Hyperopia is a frequent associated ocular configuration.

Lens–iris apposition at the pupil can initiate the obstructive sequence.

Schematic • iridocorneal drainage angle

Trabecular

Meshwork

Cornea

Iris

Angle occluded

Iris contacts the drainage region

Slide 26 · Pupillary block prevents posterior-to-anterior flow

Iris contact with the anterior lens surface may seal the pupillary passage.

Aqueous accumulates behind the iris while production continues.

Posterior-chamber pressure then increases.

Iris–lens apposition

Pupillary block

Posterior pressure ↑

Iris displacement

Slide 27 · Iris bombé converts block into angle closure

Pressure behind the iris bows the iris forward.

The bowed peripheral iris approaches and occludes the trabecular meshwork.

A major aqueous outflow pathway is thereby closed.

Schematic • iridocorneal drainage angle

Trabecular

Meshwork

Cornea

Iris

Angle occluded

Iris contacts the drainage region

Slide 28 · Primary closure is a sequence, not one event

Predisposed chamber geometry permits iris–lens apposition.

Pupillary block raises posterior-chamber pressure.

Iris bombé occludes the angle and produces marked pressure elevation.

Shallow chamber

Pupillary block

Iris bombé

Angle obstruction

Slide 29 · Sustained pressure elevation can injure the cornea

Corneal edema may follow persistent severe intraocular pressure elevation.

Bullous keratopathy can develop despite healthy endothelial-cell numbers.

Corneal consequences coexist with the potential for optic nerve damage.

Sustained high pressure

Corneal edema

Bullous keratopathy

Slide 30 · The lens epithelium also responds to severe closure

The avascular lens relies on aqueous humor for nutritional support.

Unremitting pressure elevation can damage lens epithelium.

Minute anterior subcapsular opacities may be visible by slit lamp.

Severe pressure elevation

Lens epithelial injury

Anterior opacities

Slide 31 · Secondary angle closure involves other barriers

Contractile membrane

Mechanical displacement

New vessels + stroma

Myofibroblast contraction

Peripheral anterior synechiae

Ciliary-body tumor

Iris pushed forward

Angle blocked

Slide 32 · Retinal ischemia can initiate neovascular glaucoma

Chronic retinal ischemia upregulates VEGF and other angiogenic signals.

Proangiogenic factors reach the aqueous compartment.

Thin fibrovascular membranes can develop on the iris surface.

Retinal ischemia

VEGF / angiogenic signals

Iris fibrovascular membrane

Slide 33 · A neovascular membrane alters the iris surface

The neovascular membrane may be clinically transparent.

It can smooth the usual folds and crypts of the iris.

The important pathologic behavior is subsequent contraction, not merely its presence.

Schematic • iridocorneal drainage angle

Trabecular

Meshwork

Cornea

Iris

Angle occluded

Iris contacts the drainage region

Slide 34 · Myofibroblast contraction seals the angle

Myofibroblasts within the fibrovascular membrane generate contractile force.

Contraction draws peripheral iris toward trabecular structures.

Peripheral anterior synechiae can obstruct outflow.

Iris membrane

Myofibroblast contraction

Anterior synechiae

Angle closure

Slide 35 · Tumors can contribute to neovascular or direct closure

Neovascular route

Direct mechanical route

Tumor-associated angiogenesis

Fibrovascular iris membrane

Contractile closure

Mass near ciliary body

Iris displaced into angle

Outflow occlusion

Slide 36 · Different drainage lesions converge on the same risk

Primary open-angle: Unexplained resistance despite angle access.

Secondary open-angle: Debris or venous-pressure effects.

Angle-closure: Iris obstructs the meshwork directly or through synechiae.

Open-angle

Secondary blocks

Angle-closure

Slide 37 · Neuronal susceptibility modifies the pressure response

People differ in how vulnerable their optic nerve axons are to pressure.

The source documents injury at normal pressure and tolerance of elevated pressure.

These contrasting observations imply a spectrum of susceptibility.

Susceptibility to pressure exposure

High susceptibility

Intermediate

Lower susceptibility

Same exposure ≠ same neuronal outcome

Slide 38 · Normal-tension glaucoma preserves the injury pattern

Pressure status

Injury phenotype

Within normal range

Not necessarily increased

One component of evaluation

Characteristic cupping

Visual-field changes

Still glaucomatous

Slide 39 · Elevated pressure may occur without optic neuropathy

Pressure finding

Damage evidence

Elevated intraocular pressure

Prolonged exposure possible

Risk factor

No characteristic cup change

No characteristic field change

Damage not demonstrated

Slide 40 · Pressure and damage must be assessed on two axes

A single pressure threshold cannot describe all susceptibility patterns.

Structural cupping and retinal loss characterize established damage.

The source supports a continuum rather than a simple pressure-only dichotomy.

Pressure exposure →

Injury

Severity

Elevated pressure

No damage

Normal tension

With injury

Pressure-linked

Glaucoma

Slide 41 · Retinal ganglion-cell loss is a primary lesion

Glaucoma characteristically produces diffuse loss of retinal ganglion cells.

These neurons supply axons to the optic nerve.

Their disappearance explains part of the associated nerve atrophy.

Schematic • selective inner retinal loss

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Preserved retina

Glaucomatous loss

Ganglion cells are depleted; Schematic thickness only.

Slide 42 · The retinal nerve-fiber layer becomes thin

Ganglion-cell axons form the nerve-fiber layer.

Loss of axons reduces the thickness of this inner retinal layer.

This thinning as a characteristic morphologic finding.

Schematic • selective inner retinal loss

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Preserved retina

Glaucomatous loss

Axons are depleted; Schematic thickness only.

Slide 43 · Inner retinal layers show linked atrophy

The nerve-fiber layer and ganglion-cell layer are depleted.

The figure caption identifies the inner plexiform layer as an anatomical reference.

Structural loss is most informative when aligned with the affected neuronal compartment.

Schematic • selective inner retinal loss

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Nerve-fiber layer

Ganglion-cell layer

Inner plexiform

Outer layers

Preserved retina

Glaucomatous loss

Inner retina are depleted; Schematic thickness only.

Slide 44 · Optical coherence tomography quantifies thinning

The textbook explicitly identifies OCT as a method to measure nerve-fiber-layer thickness.

An imaging measurement can track a structural consequence of neuronal loss.

The scan is evidence about tissue structure, not a substitute for all clinical findings.

Retinal nerve-fiber-layer thickness

Intact layer (schematic)

Thinned layer (schematic)

OCT measures thickness; This diagram is not an OCT scan.

Slide 45 · Optic-disc cupping reflects tissue loss

The surface cup becomes enlarged or deepened as glaucoma progresses.

The source links cupping in part to retinal ganglion-cell loss.

Cupping describes a structural change at the optic nerve head.

Schematic • nerve-head surface

Preserved rim

Expanded cup

Slide 46 · Advanced glaucoma combines cupping with atrophy

The optic nerve is atrophic in advanced chronic disease.

The surface cup may become markedly widened and deepened.

The combination of cupping and atrophy is particularly characteristic in this context.

Schematic • nerve-head surface

Preserved rim

Expanded cup

Slide 47 · A wide subdural space may signal severe nerve loss

The optic nerve is surrounded by meningeal sheaths including dura.

Marked axonal atrophy reduces the caliber of nerve tissue.

In the source figure, this produces a conspicuously wide subdural space.

Schematic • optic nerve and meningeal sheath

Dura / sheath

Optic nerve

Axons

With advanced atrophy the nerve shrinks inside its meningeal sheath.

Slide 48 · Three anatomical compartments tell one injury story

Retina: Ganglion cells and nerve-fiber layer are depleted.

Optic nerve head: Surface cupping becomes conspicuous.

Retrobulbar nerve: Advanced atrophy leaves expanded surrounding space.

Retina

Optic disc

Optic nerve

Slide 49 · Pediatric pressure elevation changes eye size

In infants and children, elevated pressure can enlarge the globe.

Developing ocular coats deform differently from adult tissue.

This age dependence is an important morphologic distinction.

Developing eye

Mature eye

Slide 50 · Buphthalmos denotes diffuse globe enlargement

Prolonged pressure elevation in early life may distend the entire eye.

The textbook terms this appearance buphthalmos.

It is a consequence of a developing eye subjected to pressure load.

Developing eye

Mature eye

Slide 51 · Megalocornea is an associated pediatric change

Corneal enlargement can occur with elevated childhood intraocular pressure.

The source names megalocornea alongside buphthalmos.

An enlarged cornea is a pressure-related structural sign, not a retinal lesion.

Developing eye

Mature eye

Slide 52 · The adult globe may develop focal staphyloma

After eye growth is complete, pressure can cause localized scleral thinning.

Uveal tissue may line the resulting ectatic sclera.

This configuration is called staphyloma.

Developing eye

Mature eye

Slide 53 · Age changes the morphology of chronic pressure

Infant / child

Adult

Buphthalmos

Megalocornea

Diffuse enlargement

Focal scleral thinning

Uveal-lined ectasia

Staphyloma

Slide 54 · Structure and function are complementary clues

Visual-field abnormality establishes functional impairment characteristic of glaucoma.

OCT thinning and disc cupping characterize different structural levels.

Pressure measurement informs risk but does not replace structure–function correlation.

Pressure

Structure

Visual field

Slide 55 · Papilledema must not be confused with cupping

Glaucoma

Papilledema

Optic nerve cup deepens

Chronic nerve atrophy

Retinal ganglion-cell loss

Disc swelling / hyperemia

Venous stasis / transport block

CSF-pressure or compression link

Slide 56 · AION has a different injury mechanism

Glaucomatous neuropathy

Anterior ischemic neuropathy

Often pressure-associated

Chronic cupping / atrophy

Retinal ganglion-cell loss

Vascular supply interruption

Acute pale disc swelling

Infarction may be permanent

Slide 57 · Inherited and toxic neuropathies broaden the differential

Glaucomatous pattern

Other optic neuropathy

Characteristic cup change

Retinal nerve-fiber loss

Pressure often implicated

Inherited / nutritional / toxic

May damage macular fibers

Alternative pathogenesis

Slide 58 · Leber hereditary optic neuropathy is mitochondrial

The source attributes Leber optic neuropathy to inherited mitochondrial gene mutations.

It follows a maternal pattern and commonly affects young adults.

This example illustrates optic nerve injury without a glaucoma-type outflow lesion.

Mitochondrial mutation

Neuronal energy vulnerability

Optic neuropathy

Slide 59 · Case: Normal pressure, abnormal nerve morphology

An eye has characteristic cup enlargement and nerve-fiber thinning.

Measured intraocular pressure is within the usual range.

Interpretation: Normal-tension glaucoma remains possible; Pressure alone does not rule it out.

Teaching case • interpretation is illustrative, not patient data

Slide 60 · Case: Sustained pressure, no documented injury

An individual has long-observed elevated intraocular pressure.

There is no characteristic field change or progressive cupping documented.

Interpretation: High pressure alone is not proof of glaucomatous neuronal loss.

Teaching case • interpretation is illustrative, not patient data

Slide 61 · Case: Retinal ischemia and iris membrane

Chronic retinal ischemia is accompanied by an abnormal iris-surface membrane.

The membrane contracts and the angle becomes closed.

Interpretation: The source mechanism is secondary neovascular angle-closure glaucoma.

Teaching case • interpretation is illustrative, not patient data

Slide 62 · Case: Trauma followed by an open-angle obstruction

Senescent erythrocytes accumulate after ocular trauma.

The angle remains anatomically open but aqueous outflow is impaired.

Interpretation: Ghost-cell secondary open-angle glaucoma.

Teaching case • interpretation is illustrative, not patient data

Slide 63 · Integrated morphologic diagnosis

Look for the characteristic retinal ganglion-cell and axonal loss.

Relate an enlarged optic nerve cup to the loss of tissue.

Interpret pressure and drainage mechanisms as etiologic context, not replacements for injury evidence.

Retina

Optic nerve head

Outflow context

Slide 64 · Final synthesis

Aqueous outflow abnormalities commonly elevate intraocular pressure.

Ganglion-cell depletion, nerve-fiber thinning and cupping define the chronic damage phenotype.

Normal-tension injury and pressure tolerance demonstrate variable susceptibility.

Age determines additional globe and corneal structural consequences.

Outflow

Susceptibility

Damage

Slide 65 · Primary reference and study boundaries

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th edition (2026).

Chapter 29, “The Eye”: glaucoma pp. 1195–1197; optic nerve pp. 1207–1209.

Morphologic schematics in this lecture are original instructional diagrams, not specimen photographs.