Glaucoma 2 - Presentation and Pathogenesis

Question 1

Primary Open Angle Glaucoma/Normal tension Glaucoma (POAG/NTG) Signs and Symptoms?

Answer 1

SIGNS
• Raised or normal intra-ocular pressure
• Open angle or deep anterior chamber
• Abnormal optic disc cupping
• Abnormal visual field
SYMPTOMS
• None until advanced or paracentral visual field defect

Question 2

Chronic Angle Closure Glaucoma (CACG) Signs and Symptoms?

Answer 2

SIGNS
•Raised or normal IOP
Open but narrow angle or moderate/deep AC
• Abnormal optic disc cupping
• Abnormal visual field
• Shallow AC
•3+ quadrants of ITC on gonioscopy
•Hypermetropia

SYMPTOMS
•None as per POAG

Question 3

Intermittent Angle Closure Glaucoma (IACG) Signs and Symptoms:

Answer 3

SIGNS
• Raised or normal IOP
• Narrow angle
• +/-Abnormal optic disc cupping
• +/- Abnormal visual field
• Shallow AC
• 3+ Quadrants ITC on gonioscopy
• Hypermetropia

SYMPTOMS
• Intermittent brow ache
•HALOES

Question 4

Acute Angle Closure Glaucoma (AACG) : Signs and symptoms:

Answer 4

SIGNS
•Red Eye
•Fixed mid-dilated pupil
• Hazy blue/green cornea
• Iritis
• IOP >40 mmHg
• Shallow AC

SYMPTOMS
• Brow ache/headache
•Blurred vision/haloes
• Nausea

Question 5

Pathogenesis of POAG theories?

Answer 5

• Pressure theory
• Vascular theory
• Mixed mechanism
• Neurodegenerative and apotptosis

Question 6

What does the pressure theory state?

Answer 6

•Trabecular dysfunction
- Trabecular meshwork gradually becomes less effective in allowing aqueous to pass through to Schlemm’s canal (increased outflow resistance)

Question 7

Ocular Perfusion Supply:

Answer 7

• The posterior segment of the eye is supplied by 2 different circulatory systems
- Retina: Central retinal artery
- Choroid: Short posterior ciliary arteries
- Optic disc: both
• Vasoactive drugs can reach the optic nerve via the choroid
A reduced bloodflow to the optic nerve increases the eye’s sensitivity to IOP

Question 8

Mixed Mechanism theory

Answer 8

•Combination of Pressure theory and Vascular Theory

Question 9

Neurodegenerative and Apoptosis theory

Answer 9

•With time as px get older, the nerves get damaged

Question 10

Mechanism of damage:

Answer 10

The exact mechanism in glaucoma is not understood completely:
•Loss of retinal ganglion cells
•Ischaemc changes at the ONH/free radicals
•Apoptosis

Question 11

Pathogenesis Primary Angle Closure Glaucoma (PACG) (8 total)

Answer 11

Restricted access to trabecular meshwork
• Hypermetropia (eg + 2.00)
• Shallow anterior chamber
• Small eyes (short axial length)
• Anteriorly inserted iris
• Increase in lens size
• Dilatation of pupil
• Trabecular Dysfunction
• Narrow gonioscopic angle

Question 12

What occurs during Angle Closure?

Answer 12

•Obstructed trabecular meshwork
•The angle between the iris and the cornea narrows or closes
•Iris pushing forward
•Cornea

Question 13

PACG: ChronicAngle Closure (CAC):

Answer 13

• The Iris slowly comes into contact with an increasing area of TM, resulting in TM dysfunction and a gradual rise in IOP

Question 14

PACG: Intermittent angle closure mechanism:

Answer 14

• The angle is narrow but open, but certain physiological states (producing dilation) lead to transient rises in IOP which resolve over variable periods of time
• This often produces transient symptoms of acute angle closure

Question 15

PACG: Acute Angle Closure - Mechanism

Answer 15

•Dilation of the pupil (physiological or otherwise)leads to the angle becoming closed
• Marked rise in IOP due to:
• pupil block
• peripheral iris tissue occluding the angle (often both present simultaneously)

Question 16

What causes Plateau Iris?

Answer 16

• Anatomical iris configuration
- anteriorly displaced ciliary body position
- anteriorly inserted or thicker iris
• The central AC is usually not shallow and the iris plane is flat or slightly convex
- Angle appears narrow and crowded
- Gonioscopy shows a “double hump” sign

Question 17

What is Plateau Iris Syndrome?

Answer 17

• ACG associated with plateau iris is usually cured by YAG peripheral iridotomy
• Plateau iris syndrome is where post-peripheral iridotomy the angle closure recurs with elevated IOP attacks

Question 18

Key points in diagnosing glaucoma:

Answer 18

• History and symptoms
- ocular and systemic
• Family Hx
• Refraction
• IOP and CCT
• Ant Chamber and Gonio
• Discs, fields, OCT

Question 19

AC Depth Assessment

Answer 19

• Peripheral
- Van Herick Technique
- Correlates well with gonioscopy
•Central
- Redmond smith technique

Question 20

Gonioscopy In Clinic + Technique

Answer 20

•Indirect Visualisation of angle structures
• Dim/dark room illumination
• Reduced slit lamp illumination & beam height
• Carried out in primary position
• Indentation
- Gentle pressure on the central cornea forces aqueous into the angle and peripheral iris
- Differentiates between appositional and synechial closure

Question 21

Grading Gonioscopy angle Width:

Answer 21

Aim
• Evaluate functional status of the angle
• Degree of closure
• Risk of closure

Evaluate
• Geometric angle width
• Shape & contour of the iris
• Most peripheral structure seen
• Presence of peripheral anterior synechiae
• Amount of trabecular pigmentation

Question 22

Types of Grading Techniques with Gonioscopy

Answer 22

• Shaffer
- Simple but functional
- Commonly used throughout Ophthalmology

• Spaeth
- Complex but comprehensive
- Used by glaucoma specialists

Question 23

What can you see with Gonioscopy?

Answer 23

In order from Iris upwards:
•Iris
•Ciliary Body Band (Pigmented)
•Scleral Spur Band (white)
•Pigmented Trabecular Meshwork Band
•Non-pigmented Trabecular Meshwork
•Schwalbes Line

Question 24

Iris in relation to Gonioscopy

Answer 24

IRIS
most posterior structure visible. Gonio assessment of the angle should include its insertion and contour.

Question 25

Ciliary Body Band

Answer 25

• production of aqueous and the regulation of its outflow
• Amount visible dependant on the level of iris insertion- related to eye size. Wider in myopia, narrower hypermetropia
• Varies in colour from greyish white to brown in appearance.
• Normal radial blood vessels can be seen in 2/3 patients with blue eyes and 10% brown.

Question 26

Scleral Spur

Answer 26

The most anterior portion of the sclera, visible as a narrow, often shiny white band It is an important landmark as it appears consistent in different eyes

Question 27

Trabecular Meshwork portions?

Answer 27

• The posterior: Pigmented TM (Approx 90% of aqueous flows out via this route)
• Anterior non-pigmented portion: Varies in appearance from little or no pigmentation to densely pigmented.
• Cases of raised EVP and trauma, can have a red appearance as blood visible in schlemms canal, which sits posteriorly to PTM.
  Angle generally considered occludable if TM cannot be seen in more than 90 degrees of the angle

Question 28

Schwalbes Line

Answer 28

The most anterior structure- represents the transition between the TM and the cornea.
Appears as an opaque flat white line, variable amount of pigment.
When pigment deposits- known as Sampaolei’s line, common finding in conditions with pigment dispersion

Question 29

Corneal Wedge

Answer 29

• 2 light reflections create a wedge shaped line which intersect at the sclero-corneal junction
• Locates Schwalbe’s line
• Imperative for localisation in difficult angles

Question 30

What Pathological Findings can you find In Angle?

Answer 30

• Peripheral Anterior Synechiae
- PACG, anterior uveitis, ICE
• New vessel formation
- Neovascular glaucoma, Fuchs heterochromic cyclitis, anterior
uveitis
•Hyperpigmentation
- PDS, pseudophakic pigment dispersion, PXF, blunt trauma,
anterior uveitis, post acute angle closure, post YAG PI
•Trauma
- Angle recession, post trabeculectomy, post cyclodialysis, foreign body