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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
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GLAUCOMA UPDATEManaging 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!
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)
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
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
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 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