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; 45:59-62)

• 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?

• 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– 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

• 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

• 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 AnalysisFast RNFL AnalysisThree 3.4mm diameter Three 3.4mm diameter circle scans in 1.92 secs circle scans in 1.92 secs allow allow allall retinal nerve retinal nerve fibres to be imagedfibres to be imaged

Acquires 768 A-scans 3* 256 A-scans per circular scan

Ocular Hypertension

Moderate glaucoma (MD -9.06)

Optic Nerve Stress