Glaucoma - Referral Flashcards
1
Q
What are the components of glaucoma referral?
A
- Hx
- IOP
- Central Corneal Thickness
- Anterior chamber assessment
- Visual Fields
- Disc Assessment
- Imaging
2
Q
Describe history in glaucoma and what to enquire about?
A
- Age and ethnic origin
o Pxs of Afro-Caribbean decent are at more risk of developing POAG
o Pxs of South East Asian decent are at more risk of developing PCAG - Previous hx of OHT or glaucoma
- Previous OH:
o Uveitis
o Pseudoexfoliation
o Pigment dispersion
o Myopia - >6D more at risk - General Health:
o Diabetes
o High blood pressure
o Peripheral vascular disease – risk of POAG
o Migraine – risk of NTG
o Raynauds phenomenon – risk of NTG
o Sleep apnoea – risk of NTG - Previous medications:
o Steroid use - Family history of glaucoma -> who? V important if 1st degree relative – if family member was very young when diagnosed and was very severe then higher risk for px
3
Q
What are the risk factors of POAG?
A
Age – prevalence increases w/ every decade
Black ethnicity – relative risk for developing POAG
Diabetes – slightly increased risk but not as strong a link – same with hypertension & peripheral vascular disease
4
Q
What are the risk factors of ACG?
A
Prevalence lower of ACG – does increase with age
Increase risk of ACG in females
Hyperopic pxs often also more at risk
South East Asian ethnicity – more anterior positioned lens and shallower anterior chamber angle – increased risk of ACG
5
Q
Describe IOP and glaucoma and when to consider referral?
A
- Measure using applanation tonometry – Goldmann is gold standard
- Protocol in place to ensure regular calibration – once a month
- Establish a baseline – using Goldmann
o Required for all suspect OHT and suspect glaucoma - Minimum of 2 readings on a single occasion
- Record time, reading & instrument
- Should consider for referral if:
o IOP > 25mmHg irrespective of CCT
o IOP 21-25 AND CCT <555µm AND aged ≤65 - Monitor in community if IOP <26 and CCT ≥555µm & no signs of glaucoma
6
Q
Describe CCT and glaucoma?
A
- Important independent risk factor for glaucoma
- At increased risk or glaucoma if CCT <555µm
- Measured using pachymeter
- Record CCT mean, SD and pachymeter used
7
Q
When should you refer based on IOP and CCT?
A
- Irrespective of other signs of glaucoma SIGN guidelines recommend referral when:
o IOP > 25mmHg irrespective of CCT
o IOP 21-25 AND CCT <555µm AND aged ≤65
8
Q
Describe anterior chamber assessment?
A
- Van Herick’s or Gonioscopy acceptable when referring
o Refer irrespective of other signs refer if:
Van Hericks technique shows a peripheral anterior chamber angle which is less than a quarter of corneal width - Technically under SIGN grade 2 on VH should also be referred but in west of Scotland this isn’t always feasible as many older hyperopic patient with patent angles will be grade 2 - up to your clinical judgement, consider gonio on grade 2’s
o Certainly refer grade 1/0 for prophylactic PI’s - Van Herick’s: take measurement from as far out as possible, just where beam splits
o Left Pic: grade 2 – referrable under SIGN guidelines
o Right pic: grade 4 – open angle - Gonioscopy:
o Refer irrespective of other signs refer if:
Gonioscopy shows 270° or more of the angle where posterior pigmented trabecular meshwork is not visible – this means that more than ¾ of angle is functioning normally
o Only for use when practitioner is confident in their abilities
o Gonioscopy only way to see abnormalities in the angle such as peripheral anterior synechaie and only way to tell for sure if the angle is open by visualising the posterior pigmented trab meshwork - Referral for narrow angles should not be based on OCT
o Low specificity for identifying narrow angles
o Gonioscopy only way to see abnormalities in the angle such as peripheral anterior synechaie
o No standardised anterior chamber assessment protocol for OCT
o Variability between examiners when identifying scleral spur
o OCT can be used as an adjunct to examine angle configuration
Plateau iris
Angle recession
Pupil block - Check anterior chamber angle for:
o Pseudoexfoliation – present on anterior lens capsule, seen when dilated
o Pigment Dispersion – look for Krukenberg spindle
Look for iris transillumination – best looked before dilation
o Iridotomy – laser procedure to create another route to help aqueous escape more freely
o All require lifelong monitoring as they are at increased risk of developing glaucoma – monitoring should include disc assessment, IOP and visual fields
These pxs should not leave more than 2 yrs between eye examinations
9
Q
When should you refer based on anterior chamber angle?
A
- Irrespective of other signs of glaucoma SIGN guidelines recommend referral when:
o Risk of angle closure:
Using Van Herick’s technique, peripheral angle width of less than a quarter of corneal thickness
using Gonioscopy, when posterior trab meshwork is not visible for ≥270°
10
Q
Describe visual fields in glaucoma?
A
- SIGN recommendation:
o Minimum of 2 VF tests with consistent findings is recommended before referral to secondary eyecare services. One test may suffice is result is unequivocal (if px had not have eye exam in 10yrs and signs show severe glaucoma then can refer without repeating) - Ideally should be same VF instrument in primary & secondary care – Humphrey Field Analyser
- Frequency doubling perimetry may also be used as an alternative to standard automated perimetry
- No recommendations in SIGN about level of loss at which referral should be considered - if repeatable and you judge it to be clinically appropriate then refer - cluster of 3 or more points on the PSD with a probability of 99% or more might be a reasonable time to refer
- Test should be 24-2 SITA Fast
- Important things to consider:
o If there is a defect – is it changing?
Progression could be glaucoma
Stable could be defect due to tilted disc or another longstanding defect
Has mean defect changed by more than 2dB?
o Does VF defect match appearance of disc?
If a superior visual field defect is present in RE is there also loss of inferior neuroretinal rim in RE?
In glaucoma shouldn’t expect field defects to cross the midline
o Px reliability:
If poor reliability on repeated occasions then VFs are less helpful for diagnosis & disc assessment & glaucoma becomes more important tools
Make use of VF indices: - 20% false positives
- 20% false negatives
- Enlargement of blind spot is not a good glaucomatous sign, most common glaucomatous defects in order paracentral, arcuate, nasal step, temporal wedge
o Usually in glaucoma should expect to a glaucomatous defect to have a cluster of more than 3 points before considering referral
Typical Patterns:
o A typical early paracentral defect is often the first VF defect – often seen in superior quadrant
This superior paracentral defect tends to be a small cluster of points in the paracentral area
o Arcuate defect may then become visible
o The more established the glaucoma becomes, paracentral defects move into becoming arcuate defects
o Pxs may also present with a nasal step or with a temporal wedge – slightly more uncommon
o Unless there is extreme glaucomatous loss affecting both superior & inferior NRR – should find that defect you are finding respects the midline because of the distribution of the nerve fibres
If defect is not respecting the midline, question if it is neurological loss or some other retinal condition that is causing VF loss
11
Q
Describe disc assessment in glaucoma?
A
- Irrespective of IOP, pxs with one or more of following findings should be referred to secondary eye care services
o Pxs with optic disc haemorrhage should be referred irrespective of other signs of glaucoma almost pathognomonic
o Pxs with cup to disc asymmetry – difference in C:D of 0.2 or greater consider referral?
12
Q
Describe imaging in glaucoma?
A
- Fundus photos – if have baseline fundus photos as well as those taking at time of referral
- OCT Scan
- GDx
- If available add to referral
- Serial analysis to assess change – from pic, superior VF defect due to inferior thinning
13
Q
When should you monitor the disc more closely?
A
- At risk groups:
o PDS - ~15% in 15yrs or 50% develop glaucoma in 4yr period – definitely high risk
o Pseudoexfoliation – high risk of conversion to glaucoma 30-50% develop glaucoma
o Myopic discs – increased risk of glaucoma
o Tilted discs – not increased risk but VF can mimic glaucoma so need to monitor to ensure no progression
o Optic disc drusen – if all else normal can monitor – if VF defect or OHT refer to secondary care as increased risk of progressive glaucoma
o Pxs with hx of primary angle closure who have had an iridotomy
o FHG – at least every 2 years if no other risk factors – at least annually if other risk factors present
o OHT – record baseline disc appearance, VF and IOP – review every two years
14
Q
When should you refer for glaucoma?
A
- Irrespective of IOP, pxs with one or more of following findings should be referred to secondary eyecare services
o Optic disc signs consistent with glaucoma in either eye
o A reproducible VF defect consistent with glaucoma
o Risk of angle closure:
Using Van Herick’s technique, a peripheral angle width of less than a quarter of the corneal thickness
Using Gonioscopy, when posterior trab meshwork is not visible for ≥270° - IOP is >26mmHg – irrespective of CCT
- IOP 21-26, Central Corneal Thickness is <555µm & px is aged under 65
15
Q
Which pxs would be discharged back to community practice?
A
- Pxs with untreated ocular hypertension where IOP is < 26mmHg & ocular examination is otherwise normal
- Pxs with untreated ocular hypertension where IOP is >25mmHg, ocular examination is otherwise normal & a low lifetime risk of glaucomatous visual disability
- Treated ocular hypertension where re-referral criteria are documented
- Pxs who have had an iridotomy & have open angle, are not on topical medication & have no evidence of glaucoma
- Pxs may be reviewed by named accredited optometrist at discretion of a consultant ophthalmologist
