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GLAUCOMA UPDATE
Managing The Glaucoma
Suspect – When Do I Refer?
DR RAJIV SHAH
EASTWOOD EYE SURGERY
Glaucoma
• Glaucoma is the most common cause of
irreversible blindness worldwide
• Often bilateral and mostly asymptomatic
• Early detection and intervention will
reduce incidence of blindness and visual
morbidity
• Well established risk factors, clinical
findings, investigations and treatments
Glaucoma Suspect
• Many people are labelled as Glaucoma Supects
(GS)
• Usually those with borderline IOP, family history
or questionable disc/field changes
• Aren’t enough eye doctors in the community to
see them all
• The optometrist is often the carer for the GS
• Patients have faith in their healthcare providers
and therefore we need to know how to manage
and when to refer (this applies for all)
Glaucoma Suspects
• Is it acceptable to follow up GS with serial white
on white fields?
• Once a field defect is seen many nerve fibres
have been lost (Klein et al.,IOVS 2004; 45:5962)
• Ideally, in the 21st century we need to aim to
detect damage at preperimetric levels
• Not always easy – compliance and cost issues,
keeping up with technology
• There are some simple and effective ways
Who to screen?
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•
•
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Everyone?
Those with family history?
Raised pressure?
Those above 40?
All of the above
It doesn’t take a long time to look at a disc
even through an undilated pupil
Key Questions
• The optometrist is often the first port of
call. Role as the eye GP?
• Family history – blindness, laser/surgeries,
eyedrops, glaucoma or ocular
hypertension?
• Isn’t always reliable
• Disregard beyond two generations and
beyond first cousins/ blood uncles and
aunts
Key Questions
• Past ocular history?
– Previous trauma
– Previous LASIK / other laser surgery (PI/ALT),
other incisional surgery and complications
– Eyedrops
– Refraction, amblyopia
Key Questions
• General Health
–
–
–
–
–
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Asthma
Hypertension
Diabetes
Sleep Apnea
Migraine
Neurological problems (CVA, tumour) – can cause
field defects
– Medications – antidepressants, sulphonamides,
steroids (inhaled, nasal, topical, systemic)
Key Questions
• Other risk factors
– Age
– Racial group
– Consanguinity
– Occupation
– Driving
– Cigarettes / alcohol
– Living arrangements / carers
Examination
•
•
•
•
•
Aided and unaided VA
RAPD
CCT
IOP (Goldmann applanation). Diurnal?
AC depth (Van Herrick > ¼ cornea thickness).
Gonioscopy ?
• Iris heterochromia, PXF, PDS
• Look for laser iridotomy, iridoplasty, PS,
Glaukomflecken, cataract (phacomorphic)
• DILATE (very, very small risk of AAC)
CCT
• Central corneal thickness
(CCT) measurements
must be performed in all
glaucoma suspects.
Those with thinner
corneas (<500 microns)
have a greater risk of
glaucoma development
and progression (OHTS
Study).
• MUST BE CENTRAL!
Phacomorphic Glaucoma
IOP
• Which method?
–
–
–
–
NCT
Applanation
Tonopen
Percussion
• Artifacts – lid pressure, breath holding, upgaze,
lash, blepharospasm, too much fluorescein,
astigmatism, corneal scar, nystagmus
• At what level is treatment mandatory?
IOP
• There are a large percentage (30% at least) of
patients who have glaucoma with normal
pressures (NPG). In some populations (Japan,
Korea) NPG incidence is 2-3 times POAG.
• The end organ damage is the same (disc
cupping) but the natural history and prognosis
may differ. There is a stronger association with
vascular disorders ( migraine, nocturnal
hypotension, Raynauds disease)
Ocular Hypertension
• Ocular hypertension when IOP > 21mmHg
• The most significant risk factor for glaucoma
development
• Different techniques/examiners can get differing
IOP
• OHTS looked at people with IOP 24-32
• Probability of progression in the treated group
(4.4%) was half that of observation group (9.5%)
at 5 years
• 90% didn’t progress at 5 years
• Role of corneal thickness
Does lowering IOP help?
• No evidence until late 1990’s
• Early Manifest Glaucoma Trial (EMGT)
• Compared immediate treatment v no or
delayed treatment on newly diagnosed
POAG patients
• Treated group had less frequent and later
progression at 6 years
• High IOP risk of vascular occlusions
Examination
•
•
•
•
•
•
•
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Disc size – must identify the limits of the disc
C/D
Notching? General rim thinning? ISNT rule
PPA?
Pallor? Colour?
Disc haem?
RNFL defects
Other disease – lid height, ARMD, DR, peripheral retina
abnormalities, RP, Laser scars, disc drusen, tilted discs,
disc pits
• THESE CAN CAUSE FIELD DEFECTS
FORGE : 5 Rules of disc assessment
(Focusing Ophthalmology on Reframing Glaucoma Evaluation)
Disc Size (Fingeret et al, Optometry 2005)
Disc Anomalies (Fingeret et al)
ISNT Rule and NFLD (Fingeret et al)
PPA
• Alpha and beta
• Alpha in most normals – hyper and
hypopigmetation of RPE
• Beta more in glaucomas – atrophy of RPE
and choriocapillaris
• Alpha more peripheral if both present
• Extent of beta corresponds with extent of
rim loss
PPA (Fingeret at al)
Investigations
• Disc photography (stereo?) – simple,
cheap and very effective. Give patient a
copy!
• Field (SAP, FDT, SWAP ) - subjective,
time consuming, late diagnosis
• OCT / HRT / GDx – expensive, useful for
progression?
Visual Fields
• Patients hate fields (nearly as much as
puff tonometry)
• Many differing machines and strategies
• Get familiar with your machine, its
limitations and the artifacts that come up
• Know how to do your own fields or
delegate to someone trained in them
• Explain and instruct the test to patients
(will not see every spot, may be gaps)
Visual Fields
• Don’t set the patient up and then leave, get
coffee, make phone calls.
• Quiet and dark room
• Let patients know that they can stop and restart.
Make sure they are comfortable
• Let them know that all doesn’t depend on one
field test (may need 3 or 4 before a pattern is
identified. A learning effect will be seen)
• If they are tired, sleepy, not well or anxious then
do it another day
Visual Fields
• Is it reliable? (correct patient, age, refraction,
eye)
• Test duration?
• Is it reproducible?
• Does it match the disc?
• Does it look like glaucoma? Follow NFL pattern?
• Make sure you are comparing tests of the same
strategy (SITA Fast v Standard, 24-2 v 10-2 or
30-2)
• Look for artifacts- lid, lens rim, pupil size,
cataract
Artifacts
Lid Artifact
Fell Asleep?
Glaucoma?
The other eye….
Where is the lesion?
OCT in Glaucoma
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•
•
•
Most recent addition in disc and RNFL imaging
Many now using it to image the disc and RNFL
RNFL loss often precedes cupping
Will detect damage before SAP (or FDT- Brusini
P, Eye 2007 Feb)
• How useful is/will it be to detect change in the
RNFL thickness ?
Fast RNFL Analysis
Three 3.4mm diameter
circle scans in 1.92 secs
allow all retinal nerve
fibres to be imaged
Acquires 768 A-scans 3* 256 A-scans per circular scan
Ocular Hypertension
Moderate glaucoma (MD -9.06)
Optic Nerve Stress