NEWSLETTER FOR OPTOMETRISTS

Early Detection Saves Sight 2012 | ISSUE 3

Since opening the Centre for Eye Health (CFEH) in late 2009 we have, together with optometrists such as you, made a difference to over 10,000 people throughout NSW and the ACT at-risk of losing their sight.

Of course there are many more people who need such help!

To help overcome critical public health challenges, our priority is to ensure the long-term sustainability of CFEH.

Our founding partners, Guide Dogs NSW/ACT and The University of New South Wales (UNSW) have been, and continue to be, central to this. However, to expand our services, reach and impact we must broaden our scope even more.

We are therefore investigating the expansion of CFEH’s unique collaboration model.

In conjunction with our current partners, referrers such as yourself, industry experts and other stakeholders, we hope to identify more partners and alternate funding sources. This will allow us to reach and help even more people at-risk of blindness.

It’s an exciting time for CFEH, and we will be seeking the contributions and insights of eyecare professionals such as yourself over the next two years.

Your input will be an important part of planning for the next phase of CFEH.

Please be assured that this process will have no impact on the services we offer you or your patients at CFEH.

Our hope is that by inviting other relevant industry groups to join the initiative, we can expand our support of optometrists and make early detection a reality for more people.

Prof. Michael Kalloniatis Centre Director

“I HAVE NEVER RECEIVED BETTER SERVICE. JUST EXCELLENT. THANK YOU!”

ROBERT, CFEH PATIENT

It’s your turn to be a CFEH client!CFEH invites you to visit the Centre as a client, combining your own ocular imaging assessment with four CPD points and a better awareness of the patient experience at CFEH.

Your individual two-hour session will include: • a one-on-one tour of the facilities with a CFEH optometrist;

• extensive examination of your eyes using CFEH advanced imaging equipment;

• insight into interpreting your own eye examination results in comparison to previous CFEH presenting clients;

• deeper understanding of what your clients experience when visiting CFEH.

Be quick as self-referred CPD appointments are limited. To book your place please complete the self-referral form provided and fax to 8115 0799 or e-mail enquiries@cfeh.com.au

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case profile:Cone DystrophySamuel, a 44-year-old male, was referred to CFEH for comprehensive follow-up of previously diagnosed cone dystrophy.

Hereportedincreasingdifficultyinrecognising colours and driving at night. He also said that a ring of vision is “missing” in his central vision (See Figure 1).

Issues to consider:

• What additional tests can CFEH providetoconfirmthediagnosisof cone dystrophy?

• What is the purpose of the follow-up and what clinical tests are indicated?

• What long-term management issues should Samuel’s optometrist address?

continued overleaf

FIGURE 1: Amsler grid test of right eye (A) and left eye (B) where shaded areas indicate

“missing” vision.

A

B

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case profile cont...Cone dystrophiesSamuel was diagnosed with cone dystrophy a year ago, and presented to CFEH for additional testing to make a full assessment of his visual and ocular status.

His unaided visual acuities were 6/12+2 in the right eye and 6/15+2 in the left eye. With pinhole, the right eye showed no improvement while the left eye improved to 6/9.5-.

Humphrey 10-2 perimetry revealed a dense central scotoma in both eyes (Figure 2) with a general reduction in sensitivity across the rest of the 20 degreefieldtested.

FIGURE 4: Spectralis OCT of right eye just superior to fovea (A), right eye through fovea centre (B) and left eye superior to fovea (C).

Note area of debri accumulation in A and C.

4A

Significantlyreducedcontrastsensitivity(MARS letter test) explained the deteriorating night vision whilst driving that Samuel had been experiencing, with right eye testing 0.84 log units and left eye 1.04 log units (normal values 1.52-1.92 log units).

Colour vision testing with the Standard D15 indicated a tritan defect in both eyes, with ten crossings in the right eye and six in the left eye.

Funduscopy revealed only subtle pigment changes at the macula in both eyes (Figure 3), and there was no visible disc pallor in either eye.

Differential diagnosis, based on age and presenting complaints, includes:

• Stargardt disease;

• macular degeneration;

• adult vitelliform macular dystrophy;

• optic neuropathy;

• cone-rod dystrophies.

4B

FIGURE 3: Fundus photo of right eye (A) and left eye (B).

3A

3B 4C

FIGURE 2: Humphrey Visual Field Analyser (HVFA) 10-2 of right eye (A)

and left eye (B).

2A

2B

Spectralis optical coherence tomography (OCT) (Figure 4) showed marked photoreceptor loss above and below the centre of the fovea.

Consistent with Samuel’s self-reported small central area of vision, the photoreceptor integrity line was relatively intact (although irregular and attenuated) in the central fovea of both eyes.

Macular thickness analysis on the CirrusOCTclassifiedthemacularthickness as thinner than normal limits in both eyes when compared with a normative database (Figure 5).

Electrophysiological testing showed reduced photopic response, 30Hz flicker(coneresponses)andnormalscotopic response (rod response). See Figure 6a-f where red indicates the normal response.

Stargardt disease, macular degeneration and adult vitelliform macular dystrophy were excluded because funduscopy and OCT imaging noted the relative

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spotlight onCone DystrophiesCone dystrophies describe a family of inherited conditions that are characterised by bilateral vision loss, central scotomata, colour vision abnormalities and variable degrees of nystagmus and photophobia1.

An accurate diagnosis is fundamental for appropriate management, and requires electrophysiological evidence of abnormal cone function.

Cone dystrophies have a variety of genetic causes and clinical presentation, and can be considered stationary or progressive1.

Stationary cone dystrophies2 refer to inherited conditions where cone function is subnormal in some way, with vision loss ranging from mild loss to legal blindness. Present from birth, stationary cone dystrophies remain relatively static throughout life. Such conditions include complete achromatopsia, incomplete achromatopsia, cone monochromatism and blue cone monochromatism.

“Electrophysiology is the gold standard for diagnosing and

monitoring the progression of cone

dystrophies.”

Progressive cone dystrophies usually present in childhood or early adult life1,3,4 and usually progress to legal blindness (on average by the age of 48 years5). Cone photoreceptors progressively deteriorate with subsequent visual decline, and rod dysfunction tends to occur later in the disease process (cone-rod dystrophy)1,3,4.

Patients with a cone dystrophy typically present with reduced visual acuity and colour vision abnormalities. Clinical heterogeneity means that funduscopic examination may reveal a near-normal macula or bulls-eye maculopathy, with variable degrees of temporal optic disc pallor4.

FIGURE 5: Early Treatment of Diabetic Retinopathy Study (ETDRS)

macula thickness grid from right eye (A) and left eye (B).

5B

5Aabsence of the relevant lesions. OCT also revealed abnormal retinal architecture, excluding a pure optic neuropathy.

The unremarkable appearance of each optic nerve head further argued against optic neuropathy, and a cone-rod dystrophy was excluded when electrophysiologyconfirmedthatscotopic visual function was within normal limits.

Although Samuel’s presenting complaint (nightdrivingdifficulty)maysuggestnyctalopia and rod involvement, cone dystrophy was diagnosed because of the reduced cone response in the cone electroretinogram (ERG) and normal rod response under scotopic testing.

Samuel’s assessment at CFEH resulted in a thorough documentation of his current clinical status, useful as a baseline for monitoring future changes and assessing long-term prognosis.

In line with recommendations that recently diagnosed people be referred for low vision assessment and services, Samuel was referred to a provider of low vision care.

FIGURE 6: Electroretinogram (ERG) traces representing responses for right eye photopic (A),lefteyephotopic(B),righteye30Hzflicker(C),lefteye30Hzflicker(D),righteye

scotopic (E) and left eye scotopic (F) stimulation. Red indicates normal response.

6A

6C

6E

6B

6D

6F

Centre for Eye Health is an initiative of Guide Dogs NSW/ACT and The University of New South Wales

our contact detailsThe University of New South Wales, Rupert Myers Building (south wing), Kensington NSW 2052

Ph: (02) 8115 0700/1300 421 960 Fax: (02) 8115 0799 Email: enquiries@cfeh.com.au Website: cfeh.com.au

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Many of your patients may already need our help.

It’s never too early for Guide Dogs NSW/ACT to help someone adapt to life with low vision - especially when all of the training and equipment is provided completely free of charge.

Best known for its amazing Guide Dogs, the organisation offers many other services which include:

•Low Vision Services: tailored one-on-one training in the home to maximise remaining vision. There is also a low vision clinic at Chatswood, delivered in partnership with UNSW School of Optometry.

•Children’s Services: we visit schools and pre-schools to educate staff on the needs of children with impaired vision, and review the environment to identify any hazards or barriers to learning and inclusion.

•Programs for people with neurological vision impairment.

•Provision of electronic mobility aids and optical aids, and free training in their use.

•Orientation and Mobility (O&M) training to help people independently move safely around their own community.

Guide Dogs instructors travel to all parts of NSW/ACT.

It’s easy to refer someone. With your patient’s permission, simply call (02) 94129300orfillinanonlinereferral form at guidedogs.com.au.

Printed August 2012.

spotlight (continued) Samuel’s case illustrates how perimetry and the Amsler grid characteristically indicate a central scotoma in both eyes when the disease is established.

Photophobia is a prominent early symptom of progressive cone dystrophies, and there may be complete loss of colour vision over time due to the involvement of all three classes of cone photoreceptors1.

OCT imaging may indicate foveal thinning and interruption of the photoreceptor inner segment/outer segment (IS/OS) line5, representing a loss of cone outer segments.

Electrophysiology is the gold standard for diagnosing and monitoring the progression of cone dystrophies.

Fundusautofluorescence(FAF)non-invasively assesses retinal health and can contribute useful information regarding disease progression. At the time of Samuel’s appointment, CFEH had not installed its FAF capability (this service is now available).

A pure cone dystrophy can produce hyperfluorescenceatthecentreofthe fovea6, and a typical FAF pattern in individuals with established disease iscentralmaculahypofluorescencesurroundedbyahyperfluorescentring7.

did you know?A Referrer Hotline is now available for registered optometrists.

REFERRER HOTLINE: 8115 0777

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. Patient names and details have been changed to protect privacy. Copyright: © 2012, Centre for Eye Health Limited. All images and content in this newsletter 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.

Inheritance patterns can be autosomal dominant, autosomal recessive (most common4) or X-linked with numerous causativegenesidentified.Theoccurrence of ABCA4 mutations are associated with poor visual prognosis4.

Althoughthereisnospecifictreatmentfor cone dystrophies, an accurate diagnosis should be made and the specificconstellationofclinicalsigns carefully documented for each individual.

Once diagnosed, patients should be fully informed about the condition and the likely prognosis. Although there are no established treatments to restore vision or prevent progression, and current prognosis is poor, emerging options include gene therapy, increased neutrophic factor expression, and implantation of retinal prosthesis to restore vision8.

The importance of regular optometric/ophthalmic reviews should be clearly explained to the patient, and followed through in order to maximise visual function and exclude ocular comorbidity.

As new therapies for cone dystrophy evolve, better knowledge of an individual’s disease progression will assist with the application of interventions at an optimal time8.

Referral for specialised genetic testing can be offered to determine the likelihood of a related asymptomatic individual developing the dystrophy, and can be useful in family planning decisions.

Low vision assessment, vision rehabilitation, orientation and mobility instruction and vocational guidance are instrumental elements of the long-term best practice management of patients with vision loss due to cone dystrophy9.

This edition prepared by Andrew Whatham, Principal Staff Optometrist & Angelica Ly, Staff Optometrist.

References available online at cfeh.com.au/clinical-guidelines.

Early Detection Saves SightAn initiative of Guide Dogs NSW/ACT and The University of New South Wales

IMAGE NEWSLETTER Edition 3 :: July 2012

References1. Michaelides M, Hardcastle AJ, Hunt DM, Moore AT. Progressive Cone and Cone-Rod Dystrophies: Phe-

notypes and Underlying Molecular Genetic Basis. Survey of Ophthalmology 2006; 51(3): p232-258

2. Michaelides M, Hunt DM, Moore AT. The cone dysfunction syndromes. Br J Ophthalmol 2004; 88: p297-297

3. Simunovic MP, Moore AT. The cone dystrophies. Eye (Lond). 1998;12 ( Pt 3b):553-65.

4. Thiadens AA, Phan TM, Zekveld-Vroon RC, Leroy BP, van den Born LI, Hoyng CB, Klaver CC; Writing Committee for the Cone Disorders Study Group Consortium, Roosing S, Pott JW, van Schooneveld MJ, van Moll-Ramirez N, van Genderen MM, Boon CJ, den Hollander AI, Bergen AA, De Baere E, Cremers FP, Lotery AJ. Clinical Course, Genetic Etiology, and Visual Outcome in Cone and Cone–Rod Dystrophy Ophthalmology. 2012 Apr;119(4):819-26.

5. Kim BJ, Ibrahim MA, Goldberg MF. Use of Spectral Domain OCT to Visualize Photoreceptor Abnormali-ties in Cone/Rod Dystrophy-6. Retin Cases Brief Rep. 2011 Winter;5(1):56-61.

6. Nan-Kai Wang,1 Chai Lin Chou, Luiz H. Lima, Wener Cella, Joaquin Tosi, Lawrence A. Yannuzzi and Ste-phen H. Tsang. Fundus autofluorescence in cone dystrophy. Doc Ophthalmol. 2009 October; 119(2): 141–144.

7. Yannuzzi LA (2010). The Retinal Atlas. Elsevier, UK.

8. Prokofyeva E, Troeger E, Bernd A, Zrenner E. Visual acuity changes in cone and cone-rod dystrophies. Ophthal Phys Optics 2012; 32: p53-59

9. American Academy of Ophthalmology Vision Rehabilitation Committee. Preferred Practice Pattern Guidelines. Vision Rehabilitation for Adults. San Francisco CA: American Academy of Ophthalmology; 2007. Available at http://www.aao.org/ppp