Issue 7: Glaucoma (Part 2) November 2010

Welcome

Professor Michael Kalloniatis, Director
Welcome to this issue of IMAGE – where we celebrate our first birthday and complete the two-part series on glaucoma by reviewing international standards for management of at-risk patients.

The past year has been an exciting and busy one for the team at Centre For Eye Health (CFEH). During the first three months we operated in trial mode to test and refine processes for delivering best-practice referrer and client services. In February we became fully operational, and have since received more than 2,500 referrals from eye-care practitioners throughout NSW and ACT.

With the majority of referrals being for glaucoma and optic nerve related tests, it appears that registered optometrists are aware of the new OBA guidelines and OAA’s universal competencies and are utilising CFEH to optimise their own management of at-risk patients.

Here at CFEH we complement established referral pathways in eye health serices, adding resource capacity now that demand is increasing rapidly. With no waiting list, the average client is seen within three weeks of being referred. It’s also great that barriers to advanced ocular imaging are being removed, with many people from lower socio-economic backgrounds and disadvantaged areas accessing the Centre.

CFEH sees its role as supporting the ophthalmic profession, and we look forward to partnering with more eye-care practitioners in the future to continually improve patient outcomes through the earliest possible detection of eye diseases.

Prof. Michael Kalloniatis

Centre Director

Centre Update

In November, we celebrate our first full year of operation. We are proud to be making a difference in the lives of our clients, helping to save their sight through early detection and monitoring. Other achievements during the year include:

  • Optometrist registrations ahead of target, with more than 50% of NSW and the ACT practitioners registered.
  • More than 2,500 referrals received, with one optometrist referring more than 100 times, and one ophthalmologist more than 50 times.
  • Over 70% of clients are from outside the Sydney central metropolitan area.
  • More than 200 optometrists attended various Series of Continuing Ophthalmic Professional Education (SCOPE) events.

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Case Report

Can one test diagnose glaucoma?

Frank, a 47 year-old white male, presented to his optometrist with problems seeing small print. At the consultation, his intraocular pressures (IOPs) were measured at 24mmHg in the right eye and 26mmHg in the left.

Visual fields were reported as unreliable, but full to FDT perimetry, with the optic nerve appearing suspicious superiorly in both eyes.

Figure 1: Suspicious optic disc in Dora’s right eye.
Figure 1: Fundus photo of the left optic nerve.

Issues to consider

1. Is there one test that diagnoses glaucoma?

2. What further tests, according to current best-practice guidelines, should/could be performed both in your practice and through CFEH to best manage Frank’s current ocular health?

Results and Discussion

This case illustrates the value of multiple imaging technologies in patient management.

Frank was referred to CFEH by his optometrist for a glaucoma assessment due to elevated IOPs and suspicious optic nerve head appearance. Until now, he has had normal ocular, medical and family histories, with no known glaucoma specific risk factors.

GDx Pro uses birefringence to assess the RNFL integrityOn attendance at CFEH, applanation intraocular pressures were 24mmHg in both eyes at 3pm. Central corneal thickness was 615μm in the right and 612μm in the left. Sussman Goniscopic examination revealed angles open to the ciliary body band in both eyes through 360 degrees with grade one pigmentation. There were no signs of anterior angle abnormalities consistent with causes of secondary glaucoma.

Examinations utilising the GDx Pro, Optical Coherence Tomography (OCT), Heidelberg Retina (optic nerve head) Tomography (HRT3) and Matrix Frequency Doubling Perimetry (FDT) were performed.

GDx Pro retinal nerve fibre layer (RNFL) assessment uses birefringence to assess the location, density and organisational structure of the retinal nerve fibre layer. The results (Figure 2) showed a loss of RNFL in the nerve fibre layer maps superiorly in both eyes.

Figure 2: GDx Nerve fibre layer map for the left eye and TSNIT curves.   Figure 2: GDx Nerve fibre layer map for the left eye and TSNIT curves.
Figure 2: GDx Nerve fibre layer map for the left eye and TSNIT curves.

The TSNIT curves showed a relative flattening in the superior section (Figure 2) with the line graphs falling below the grey area representing the normative range based on 251 normal subjects aged from 18 to 82. These curves are calculated in the area between the two white peripapillary circles shown in the nerve fibre layer maps.

The Deviation maps and summary parameters (Figure 3) also flagged the superior RNFL in both eyes as falling below the normal range compared with the instruments normative database (see GDx Pro Instrument Profile for more details).

Figure 3: GDx Deviation map for the left eye and summary parameters for both eyes.   Figure 3: GDx Deviation map for the left eye and summary parameters for both eyes.
Figure 3: GDx Deviation map for the left eye and summary parameters for both eyes.

OCT RNFL imaging results were in general agreement with the GDx Pro results and analysis.

HRT3 optic nerve head tomography classified both optic nerves as small in size, indicating an increased significance to the moderate cupping suggested in the topography image (Figure 4). The Moorfields Regression Analysis considered the superior neuro-retinal rim in the right eye to be ‘borderline’ and the left to be ‘outside normal limits’ (See IMAGE issue 6 for further information on the HRT3).

 Figure 4: HRT3 topographic image showing the extent of the cupping of the optic nerve head.
Figure 4: HRT3 topographic image showing the extent of the cupping of the optic nerve head.

A stereoscopic assessment did not show any visible RNFL wedge or slit defects however the neuro-retinal rim appeared thin superiorly in both eyes with the ‘ISNT rule’ not being obeyed as a result.

FDT fields were once again affected by poor fixation, however the results suggest an inferior relative depression in the pattern deviation maps of both eyes (Figure 5).

Figure 5: Matrix pattern deviation result for the left eye.
Figure 5: Matrix pattern deviation result for the left eye.

Despite his relatively young age, low risk profile and thick corneas, the structural and functional analysis combined with the visual field all suggest that there is glaucomatous damage. As a result, it was recommended that Frank be referred to an ophthalmologist for appropriate management.

Prepared by: Michael Yapp, CFEH Principal Optometrist

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Eye Condition Spotlight: Glaucoma (Part 2)

In its universal standards, the Optometrists Association Australia (OAA ) sets out that all optometrists are expected, at entry-level, to diagnose a range of ocular conditions, such as glaucoma.

Basic competency includes undertaking a range of clinical tests and interpreting results from advanced equipment, such as OCT and HRT.

Centre for Eye Health exists to support eye-care practitioners in meeting these standards.

In the last edition of IMAGE the prevalence of glaucoma and ocular hypertension in the community was discussed, along with some of the risk factors which can be determined from a patient’s history.

In this issue we look at some of the best-practice recommendations for conducting an eye examination with patients at risk of glaucoma. The following organisations, each having proposed specific recommendations, are in agreement with the following protocols for examining patients with suspected glaucoma.

  • Optometry Board of Australia (OBA 2010)
  • National Health and Medical Research Council (NHMRC 2009)
  • National Institute for Health and Clinical Excellence (NICE 2009)
  • American Academy of Ophthalmology (AAO 2008)

The OBA states that optometrists who are endorsed to prescribe therapeutic drugs must have access to specific equipment, which enables the following to be measured:

1.Intraocular pressure (IOP)
2.Visual fields
3.Optic nerve head analysis and imaging
4.Retinal nerve fibre analysis and imaging
5.Anterior chamber angles and analysis of this structure
6.Corneal thickness

NHMRC, NICE and AAO also recommend the above with some slight variations for patients with suspected primary open angle glaucoma. These include:

7.Measurement of visual acuity (AAO)
8.Evaluation of the pupils (AAO, NHMRC)
9.Central corneal thickness (AAO, NHMRC, NICE)
10.Measurement of IOP with the time recorded (AAO)
11.IOP should be measured with Goldmann tonometry (NICE)
12.Slit-lamp biomicroscopy of the anterior segment (AAO)
13.Documentation of the optic disc morphology, best performed by colour stereophotography or computer-based image analysis (AAO)
14.Depth analysis of the anterior chamber using gonioscopy (NICE)

Given the potential for shared care of glaucoma patients between participating optometrists and ophthalmologists in Australia, measurement of the above are important to establish baseline characteristics of the eye(s) concerned and to monitor whether treatment strategies are successful.

Centre for Eye Health (CFEH) is able to provide these services, on behalf of referring practitioners, using the following instrumentation:

  • IOP measurement: Goldmann, Perkins, iCare, Pascal.
  • Central corneal thickness: Ultrasound, Pentacam, Haag Streit (Lenstar, OLCR). 
  • Visual fields: Matrix, Humphrey Visual Field Analyser.
  • Optic nerve head imaging: Canon mydriatic and non-mydriatic photography and stereophotography, HRT3.
  • Optic nerve head analysis: Optovue OCT, HRT3, Spectralis OCT, Zeiss Cirrus OCT.
  • Retinal nerve fibre layer imaging and analysis: Zeiss Cirrus OCT, GDx Pro.
  • Anterior Chamber: Goniscopy, Pentacam, Anterior Eye OCT.
  • Anterior eye photography: Haag Streit digital systems.

CFEH is committed to ensuring that imaging and diagnostic systems are updated as required to provide referring practitioners with the most advanced information available.

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GDx PRO Scanning Laser Polarimeter

INSTRUMENT PROFILE

GDx PRO Scanning Laser Polarimeter

The GDx PRO is designed to assess patients that are at risk of, or are affected by, optic neuropathies (in particular glaucoma).

It can provide information regarding symmetry analysis between the two eyes, as well as comparisons to a normative database and guided progression analysis.

Click here for full profile >>

See entire equipment list for the Centre >>

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STAFF PROFILE

Anna Delmadoros - Principal Optometrist
Anna Delmadoros
Principal Optometrist

Anna Delmadoros, Principal Optometrist at CFEH, is particularly interested in new technologies for the early detection and management of glaucoma.

“Sophisticated ocular imaging technology is so important for identifying eye disease before irreversible damage occurs” she says “and having access to such state-ofthe-art instrumentation is what I most value about working at CFEH.”

Anna is also the Principal Staff Optometrist for ocular pathology and advanced ocular techniques at the UNSW School of Optometry and Vision Science, and has been extensively involved in undergraduate and postgraduate teaching since 2000. Actively involved in the continuing education of optometrists nationwide, the NSW division of the OAA awarded her the Josef Lederer Award for Excellence in Optometry in 2008.

Anna graduated from UNSW with first class honours in optometry in 1996 and completed her Master of Optometry degree in 2005.

CFEH Staff >>

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Next Issue

Benign or sinister dark lesions in the fundus

Joe, a 30 year-old white male, presented for a general eye examination with his optometrist, who noted a dark lesion in the left fundus near the macula.

  • What imaging devices can give the optometrist more information about the lesion?
  • Does OCT of such lesions provide useful information beyond that obtained through fundoscopy?
  • What are the implications if the lesion was located on the optic nerve head?

More issues of Image >>

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Referrer Hotline

A Referrer Hotline is now available for registered optometrists.

REFERRER HOT LINE: 8115 0777

This dedicated phone line is staffed by clinical professionals between 9am and 5pm weekdays. It is the quickest way for referrers to directly discuss results and management options.

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References

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Disclaimer: This newsletter is not intended to provide or substitute advice through the appropriate health service providers. Although every care is taken by CFEH to ensure that this newsletter is free from any error or inaccuracy, CFEH does not make any representation or warranty regarding the currency, accuracy or completeness of this newsletter.

Copyright: © 2010, Centre for Eye Health Limited. All images and content in this letter are the property of Centre for Eye Health Limited and cannot be reproduced without prior written permission of the Director, Centre for Eye Health Limited.

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