Presentation on theme: "GLAUCOMA UPDATE Managing The Glaucoma Suspect – When Do I Refer? DR RAJIV SHAH EASTWOOD EYE SURGERY."— Presentation transcript:
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 21 st 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 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
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 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