DIS - Glaucoma Treatment and Progression Tutorial - Week 7 Flashcards
Is the majority of glaucoma chronic or acute?
Chronic
What is the first step of glaucoma treatment?
Grading the severity
Describe the MEC glaucoma clinic 5 category classification for glaucoma (GSS). Describe where on the glaucoma continuum each of these fits.
High risk ocular hypertension - acceleration of apoptosis
Pre-perimetric glaucoma - ganglion cell death to RNFL change (detectable)
Early perimetric glaucoma - SWAP and SAP VF changes
Moderate perimetric glaucoma - VF change (moderate)
Severe perimetric glaucoma - VF change (severe) and blindness
Define ocular hypertension.
IOP >21mmHg without structural/functional defects
Does ocular hypertension always mean an increased risk of glaucoma? Explain.
No, some pose no greater risk than normal, while others have a much likelihood of developing into glaucoma
Should all ocular hypertension be treated?
No, only high risk ocular hypertension
List 5 factors that will indicate high risk ocular hypertension.
Central corneal thickness <555um IOP >26mmHg Age over 60 years C/D greater than 0.7 Risk of 15% or more by OHTS risk calculator
Consider the risk given by the OHTS risk calculator, what is a disadvantage and what categories of risk should be treated vs monitored?
It doesnt consider every risk factor
Monitor low/moderate risk
-treat if multiple additional risk factors present
Treat all high risk
Describe what is meant by pre-perimetric glaucoma. Include ocular (3) and imaging signs (2).
No visual field defect, but 3 or more ocular and/or imaging signs of glaucoma Ocular signs -rim thinning -disc haemorrhage -NFL wedge defect Imaging signs -GCC defect -RNFL defect
What stage of glaucoma is the most likely of all to get wrong and why? Why does this error tend to occur?
Pre-perimetric glaucoma due to red disease (false positives)
- up to 25% of all scans
- tends to occur if OCT is used in routine exams
Describe what is meant by pre-perimetric glaucoma (2). Include three VF defects typical at this stage and give two indications of severity (MD and VFI).
3 or more ocular/imaging signs Repeatable VF defect Typical defects are nasal step, arcuate, and paracentral defects Severity -MD 0 to -6dB -VFI 100 to 80%
Describe what is meant by pre-perimetric glaucoma (2). Include a VF defect typical at this stage and give two indications of severity (MD and VFI).
3 or more ocular/imaging signs Repeatable VF defect Typically a large defect in one hemifield Severity -MD -6 to -12dB -VFI 80 to 60%
Describe what is meant by pre-perimetric glaucoma (2). Include two VF defects typical at this stage and give three indications of severity (MD and VFI).
3 or more ocular/imaging signs
Repeatable VF defect
Typical defects are a large defect in one hemifield and a moderate defect in the other hemifield
Severity
-MD worse than -12dB
-VFI less than 60%
Any VF defect within 5 degrees of fixation
Up to what percentage of ganglion cells may be lost before early glaucomatous defects become evident?
40-50%
In addition to risk factors, list 5 other factors that influence the decision to treat ocular hypertension to prevent glaucoma.
Patient age Life expectancy Medical co-morbidities Burden of treatment Patient preference
What percentage of untreated ocular hypertension will progress to glaucoma? What does it reduce to if IOP is lowered by 22%?
10%
Lowering the IOP by 22% reduced glaucoma rate to 5%
When detecting the conversion from ocular hypertension to glaucoma, was this detected predominantly by structural changes or visual field losses?
Predominantly structural change
What percentage of untreated early perimetric glaucoma will remain stable?
38%
Keeping in mind the risk of progressing to glaucoma from ocular hypertension (and early perimetric glaucoma getting worse), describe a major factor that influences whether or not treatment should be initiated. Explain why it matters (2).
You may elect to closely monitor or begin treatment
-can wait for structural/functional losses before deciding to treat
Age at the time of diagnosis is very important
-younger patients usually require treatment as they will have the disease for many years
-often dont need to treat the elderly (>80) as they may not live ling enough to lose vision
Do moderate and severe perimetric glaucoma always require treatment at any age?
Almost always
What must be done if treatment is initiated?
Target IOP must be set
What is considered the baseline IOP when setting a target IOP?
Highest recorded IOP prior to treatment
List 6 factors that can influence target IOP?
Glaucoma severity grading Ocular risk factors Systemic risk factors Family history Age Life expectancy
Describe the target IOP for low, medium, and high risk given by the NHMRC guidelines.
Low - 20% decrease or 24mmHg
Moderate - 30% decrease or 17mmHg
High - 14mmHg
Describe the target IOP for each stage of the five stages of glaucoma.
High risk OTH - 20% Pre-perimetric - 25% Early perimetric - 30% Moderate perimetric - 40% Severe perimetric - under 14mmHg This varies from practitioner to practitioner
If the difference between baseline and target IOP is greater, what is more likely required?
Surgical intervention
List 6 treatment options for glaucoma.
Topical eyedrops Oral medications Laser -SLT Cataract surgery and MIGS Incisional surgery -trabeculectomy -tube shunts Ciliary body ablation
What percentage of patients can reach target IOP with a single drug? What about with maximal medical therapy?
Single drug - 50%
MMT - over 90%
-MMT in glaucoma is 4 different classes of drugs