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Shared Care and Ocular Therapeutics > Glaucoma Topics > Flashcards

Glaucoma Topics Flashcards

1
Q

Aspects of History Relevant to Glaucoma Assessment/Referral

A
  • Ethnicity
    • POAG (afrocarribbean)
    • ACG (east asian)
  • Prev Ocular History
    • OHT/Glaucoma
    • Uveitis
    • Pseudoexfoliation
    • Pigment dispersion
    • Myopia (>6.00DS)
  • General Health Considerations
    • DM
    • HBP
    • Peripheral vasculature disease
    • Migraine
    • Reynauds
    • Sleep apneoa
  • Medications
    • Steroid use
  • Family History
    • 1st degree relative is higher risk
    • Younger onset is more severe
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2
Q

Measuring IOP in accordance with SIGN Guidelines

A
  • Measured using application tonometry
  • Regular calibration needed (at least monthly)
  • Is minimum of 2 readings on single occasion
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3
Q

When to Refer Based on IOP in accordance with SIGN Guidelines

A
  • Consider referral if:
    • IOP > 25mmHg
    • IOP 21-25mmHg and CCT <555um if ages under 65
  • Monitor in community if:
    • IOP <26mmHg and CCT >555um with no signs of glaucoma
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4
Q

Measuring CCT in Accordance with SIGN Guidelines

A
  • Increased risk if under 555um
  • Record CCT, sd and the instrument used
  • If sd is high then repeat measurement
  • Record IOP and CCT separately and treat as separate risk factor
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5
Q

When to Refer Based on AC Angle in Accordance with SIGN Guidelines

A
  • VH or gonioscopy are acceptable
  • Refer irrespective of other signs if:
    • VH grade 2 or less
    • 270 degrees or more where pigmented TM is not visible on gonioscopy
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6
Q

When to Refer Based on Visual Fields in Accordance with SIGN Guidelines

A
  • At least 2 tests with repeatable findings recommended
  • One test may suffice if result is unequivocal
  • Ideally same VF instrument for both tests
  • No SIGN recommendation on the level of VF loss:
    • If repeatable and clinically appropriate then refer
    • Cluster of 3 or more points
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7
Q

Patients Reliability Indices on Visual Fields

A
  • 20% False Negatives
  • 20% False Positives
  • 30% Fixation Losses
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8
Q

When to Refer Based on Optic DISC assessment in Accordance with SIGN Guidelines

A
  • Irrespective of IOP refer if:
    • Disc haemorrhage
    • Cup:disc asymmetry > 0.2
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9
Q

Who to Monitor More Carefully

A
  • Pigment dispersion syndrome
  • Pseudoexfoliation
  • Myopic disc
  • Tilted disc
    • VF can mimic glaucoma
  • Optic disc drusen
  • Family history
  • OHT (still 2 year monitoring)
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10
Q

Angle Structures as Visible on Gonioscopy

A

I - Iris
Can - Ciliary Body
See - Scleral Spur
The - Trabecular Meshwork
Line - Schwalbe’s Line

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11
Q

What are Iris Processes

A
  • Small tenuous extensions of the anterior iris surface
  • Insert at the scleral spur
  • Present in around 1/4 of individuals
  • More prominent in brown eyes and children
  • Peripheral anterior synechiae are more substantial and insert more anteriorly
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12
Q

G1 Gonioscopy Lens

A
  • View angle by viewing mirror and rotating through 360 degrees
  • Single mirror with 62 degree viewing angle
  • Highest mag of common gonioscopy lenses (1.5x)
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13
Q

G2 Gonioscopy Lens

A
  • Has 2 mirrors with slightly different angles, so different views of angle
  • View angle by viewing in mirror and rotating through 180 degrees
  • Highest mag of common gonioscopy lenses (1.5x)
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14
Q

G3 Gonioscopy Lens

A
  • AKA Goldman lens
  • Can be used to view peripheral angle and peripheral fundus
  • Rotate through 360 degrees to view full angle
  • Mag 1.06x
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15
Q

G4 Gonioscopy Lens

A
  • 4 Mirrors for viewing all set at same angle
  • View whole angle by using 4 mirrors and rotating 45 degrees
  • Has detachable handle for stability if non-flange
  • Mag is 1.0x, but can use SL mag
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16
Q

Advantages of Direct Gonioscopy

A
  • Good magnification (1.5x) using SL
  • Easy orientation for observer
  • Possible to simultaneously compare both eyes
  • Can be used in bed bound patients
  • Very little corneal distortion
  • Wide FOV
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17
Q

Disadvantages of Direct Gonioscopy

A
  • Time consuming
  • Requires large working area
  • May require assistant
  • Requires separate illumination and magnification
  • Low magnification depending on SL
  • Cannot creat optical section to locate Schwalbe’s Line
  • Poor for detail deepening on SL
  • Difficult technique
18
Q

Advantages of Indirect Gonioscopy

A
  • Focal illumination allows location of Schwalbe’s line
  • Magnified view of angle
  • Excellent for fine detail
  • Stable image
  • Technique is simple
  • Useful for surgical treatment
  • Can use ordinary SL
  • Px sitting up or supine
  • Photography/video possible
19
Q

Disadvantages of Indirect Gonioscopy

A
  • Poor lateral view (stereopsis difficult)
  • Uncomfortable for patient?
  • Can require coupling fluid
  • Observations reversed
  • Small FOV
  • Expensive lenses
20
Q

Advantages of a Non-Flange Gonioscopy Lens

A
  • Use saline to wet lens
  • No coupling fluid required
21
Q

Disadvantages of a Non-Flange Gonioscopy Lens

A
  • Less stable image
22
Q

Advantages of Flange Gonioscopy Lens

A
  • Easier to get initial image
  • View is more stable
23
Q

Disadvantages of Flange Gonioscopy Lens

A
  • Needs coupling fluid (viscotears/celluvisc)
  • Coupling fluid can reduce retinal image quality and impair ability to complete fields
  • Cannot perform indentation gonioscopy
  • Bubble formation causing issues with viewing
  • Messy
24
Q

Corneal Wedge

A
  • Helps determine if angle is open or closed
  • Beam is displaced 5 to 10 degrees temporally or nasally
  • The tip of the wedge is Schwalbe’s Line
  • If next to iris then angle is closed
  • If large gap then angle is open
25
Q

Indentation Gonioscopy

A
  • Useful to help differentiate between the various pigmented structures
  • Positional angle closure will open with pressure
  • Synechiae angle closure will not open even with pressure
26
Q

Shaffer Gonioscopy Grading

A
  • Corresponds to VH grading
    • Anterior CB (Grade 4)
    • Scleral Spur (Grade 3)
    • TM (Grade 2)
    • None (Grade 0)
27
Q

Recording Gonioscopy Results

A
  • Most posterior visible structure
  • Shaffer grade each quadrant
  • Iris processes/synaechiae (extent and position)
  • Pigmentation (graded 0-4)
28
Q

Physiological Variations Visible on Gonioscopy

A

Variations in TM Pigment
- Can be physiological or due to PDS/Pseudoexfoliation
Sampolesi’s Line
- Heavy pigmentation anterior to Schwalbe’s line
- Can be normal or due to PDS/Pseudoexfoliation
Iris Processes
- Ensure they are not peripheral anterior synechiae

29
Q

Pathological Variations Visible on Gonioscopy

A

Peripheral Anterior Synechiae
- Differentiate from iris processes
- Iris processes are more posterior
Angle Neovascularisation
- Neovascular vessels are leaky and cross structures
PDS
- Increased pigment in angle
- Visible defect on retro-illumination
- Krukenburge spindle on posterior cornea
Pseudoexfoliation
- Deposits in AC angle
- Deposits on anterior lens surface

30
Q

Order of Prescribing Glaucoma Medications

A

1st line
- Prostaglandin analogue
2nd Line
- Beta blocker/Carbonic anhydrase inhibitor/Alpha agonist
3rd Line
As above
4th Line
- As above (rarely pilocarpine)

31
Q

Prostaglandin Analogues in Glaucoma Treatment

A
  • Mechanism
    • Increases uveoscleral outflow by ciliary muscle relaxation
  • Action
    • 30 to 35% reduction
  • Effect
    • Initial effect after 2 hrs
    • Peak effect after 8 to 12 hrs
    • Effect duration upto 24 hrs
  • Contrainidcations
    • Uveitis
    • CMO
    • Recurrent HSK
    • Relative cohtrainidaction in aphakia/pseudoaphakia
    • Pregnancy
  • Examples
    • Latanoprost
    • Travoprost
    • Bimatoprost
    • Tafluprost
32
Q

Beta Blockers in Glaucoma Treatment

A
  • Mechanism
    • Blocks receptors on ciliary body, decreasing aqueous production
  • Action
    • 25 to 30% reduction
  • Suffer from tachyphylaxis i.e. eventually become less effective
  • Contraindications
    • Arrythmias, cardiac failure, COPD
  • Cautions
    • Px taking calcium channel blockers
    • Px already on systemic beta blockers
    • Elderly px
  • Examples
    • Timolol
    • Levobunolol
    • Carteolol
    • Metipranolol
    • Betaxolol (cardioselective)
33
Q

Carbonic Anhydrase Inhibitors in Glaucoma Treatment

A
  • Mechanism
    • Inhibit carbonic anhydrase in ciliary epithelium, reducing aqueous production
  • Action
    • 18% reduction
    • Possible improved optic nerve perfusion due to local vasodilation
  • CAI can affect metabolism of corneal endothelium so may cause loss in clarity
  • Examples
    • Dorzolamide
    • Brinzolamide
34
Q

Carbonic Anhydrase Inhibitors Side Effects

A
  • Ocular Side Effects
    • Transient stinging
    • Transient blurring
    • Allergy
    • SPK
  • Systemic Side Effects
    • Sulphonamide allergy
    • Stevens-Johnsons Syndrome
    • Aplastic anaemia
35
Q

Alpha 2 Agonists in Glaucoma Treatment

A
  • Mechanism
    • Reduces aqueous production and increases uveosleral outflow
  • Action
    • 25% reduction
    • 4th line due to high rate of allergies
    • Experimental neuroprotective properties on optic nerve
  • Contraindications
    • Children
    • People with depression
  • Examples
    • Apraclonidine
    • Brimonidone
36
Q

Alpha 2 Agonists Side Effects

A
  • High rate of allergy
  • Conjunctival hyperaemia
  • Follicular conjunctivitis
  • Dry mouth
  • Systemic BP reduction
  • Fatigue and drowsiness
37
Q

Prostaglandin Analogues Side Effects

A
  • Mild conjunctival hyperaemia
  • SPK
  • Ocular irritation
  • Increased iris pigmentation
  • Lengthening of lashes
  • CMO
  • Reactivation of HSK
  • Exacerbation of asthma
  • Lower lid skin hyperpigmentation
38
Q

Beta Blockers Side Effects

A

Ocular Side Effects
- Corneal hypaesthesia
- SPK
- Dry eye
- Burning/stinging
- Pseudopemphigoid
Systemic Side Effects
- Anxiety
- Depression
- Loss of libido
- Arrhythmia
- Hypotension
- Exacerbation of asthma
- Raynauds

39
Q

Cholinergic Agents in Glaucoma Treatment

A
  • Mechanism
    • Increase trabecular outflow via ciliary muscle contraction and minor decrease in aqueous inflow
  • Action
    • 20% reduction
  • Example
    • Pilocarpine 1-4% 4x daily
40
Q

Pilocarpine Side Effects

A

Ocular Side Effects
- Ciliary muscle spasm
- Brow ache
- Accommodative myopia
- Miosis (VF constriction)
- Retinal detachment
- Exacerbation of uveitis
- Cataract formation
- Angle closure
Systemic Side Effects
- Bradycardia
- Nausea
- Sweating
- Diarrhoea
- Bronchospasm

41
Q
A

Shared Care and Ocular Therapeutics (10 decks)

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