- Eye Health
|Welcome to the first edition of IMAGE for 2011, where we examine the challenges of distinguishing a benign naevus from a small melanoma. I’d also like to take this opportunity to reflect on our first year, when we saved sight for ordinary Australians and started to establish CFEH as a centre of clinical excellence.|
What we are most proud of is improving access to early detection services for people in the community. Hospital waiting times and private specialist fees are a barrier for many people in accessing timely diagnostic services. This can lead to irreversible damage occurring while people wait, and many more people can slip through the cracks until eye disease starts affecting their day to day activities.
|Early detection of eye disease is a necessary health service that is currently out of reach for many people in the community at the time when they need it most.|
In 2010, CFEH clients reported that after their appointment 33% were diagnosed with an eye disease, commenced treatment or were referred on to a specialist. Another 33% will continue to be monitored to ensure earliest possible intervention should it be required.
For many of these people, free access to advanced ocular imaging services has allowed them to commence treatment sooner than they may have otherwise, and therefore have a better chance of preserving their vision in the long term.
I am proud of what we have achieved in just one year, and excited about doing even more in the years to come.
Prof. Michael Kalloniatis
Lesions in the fundus: benign or sinister?
|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. Joe was referred to Centre for Eye Health (CFEH) for further investigation of the lesion. There was no family history of eye disease and Joe did not have a history of eye injury or surgery. His visual acuity was 6/5 in both eyes.|
Figure 1: Fundus photograph of pigmented lesion in Joe’s left eye.
Issues to consider
1. Which imaging devices would give the optometrist more information about the lesion?
2. Will Optical Coherence Tomography (OCT) of such lesions provide more useful information than fundoscopy?
2. What are the implications if the lesion was located at the optic nerve head?
Joe was referred to CFEH for documentation of pigmented areas, assessment of morphological characteristics and visual function assessment. Tests included posterior pole photography, wide-field fundus photography (Optomap), Optical Coherence Tomography (OCT) and visual field assessment.
A pigmented lesion of approximately two disc diameters was evident just above the left fovea (Figure 1). OCT suggested that the lesion was elevated, and measured approximately 4mm in diameter and was ~0.3mm thick. Thickness into the choroid was excluded (Figure 2). Drusen or lipofuscin deposits were not detected and the visual field assessment was normal.
Results indicated an absence of drusen and a close proximity to the foveola, both melanoma risk factors (Table 1). Combined with Joe’s history of non-ocular neoplasm, and the Collaborative Ocular Melanoma Study (COMS)1 classification, CFEH recommended full evaluation by an ophthalmic oncologist. Joe has since made an appointment to see such a specialist.
In another case, a 61 year-old white female, was also referred to CFEH for further evaluation of a pigmented lesion in the left eye, with overlying deposits. Optomap and fundus imagery indicated that the pigmented area was approximately 1-2 disc diameters in size with overlying drusen in the mid-periphery of the superiortemporal region (Figure 3). The separation of red and green imagery places the pigment in the choroid.
OCT imaging, (inverted to enhance the choroidal view) illustrated a pigmented choroidal area with overlying drusen.
There were no breaks in the retinal pigment epithelium (RPE) and while the drusen disrupted the RPE, and overlying inner retina, the pigmented choroidal area appeared flat (Figure 4).
As a result, this area appears to be a small choroidal naevus with overlying drusen. Photographic and OCT monitoring in 12 months was recommended to Anna’s optometrist to confirm stability.
Prepared by: Michael Kalloniatis and George Rennie
Choroidal naevi are the most common type of benign intraocular lesions, occurring in around 10 per cent of the general population(2-4). They comprise a large number of spindle cell melanocytes, and around 90 per cent are posterior to the equator. Most develop during the teenage years, when ocular pigment content increases, and less commonly during adulthood. Some display detachment of the retinal pigment epithelium or choroidal neovascularisation, and lesions can be amelanotic(2).
Ultrasound of a choroidal naevi will show a flat or slightly elevated lesion with high internal reflectivity(2-4). OCT studies have further characterised a choroidal naevi as follows:
As a result, naevi can lead to visual disturbance.
Management of small naevi requires careful documentation to clearly establish any progression, an imaging service that CFEH specialises in. The initial assessment should include stereoscopic fundus examination and colour imagery. The follow-up assessment, four to six months later, will analyse any growth. If the naevi remains stable the patient should then be monitored with examinations every six to twelve months(4).
Large naevi, or those containing suspicious features (Table 1), may warrant baseline fundus photography, combined with ultrasonography and OCT assessment. The patient should be reviewed again within three to four months, and then four to six months if no change, tapering to a 12 month cycle as the stability of the lesion is confirmed4. The growth potential of malignant tumours requires a short initial review, and such cases need a low threshold for referral to an ophthalmologist or CFEH for further assessment. The cumulative growth rate of untreated small choroidal melanomas from the Collaborative Ocular Melanoma Study (COMS) was 11 per cent after one year, 21 per cent after two years and 31per cent after five years(1).
When malignancy is suspected immediate referral to an ophthalmic oncologist is recommended. The greater the number of risk factors identified in the patient (Table 1), the higher the likelihood of malignancy(2).
Although the prevalence of naevi is around 10 per cent, the rate of conversion to melanoma is low and is estimated to be almost one in 9,000(9). With a population of approximately seven million in New South Wales, this means that of the estimated 700,000 cases of naevi, epidemiological data predicts that 79 will convert to melanomas per annum. A self audit of your clinical records will determine if the approximated 10 per cent naevi detection rate has been achieved. A long-term prediction of naevi-tomelanoma conversion rate can also be calculated.
Choroidal melanoma is the most common primary intraocular malignancy in adults (particularly in Caucasians) and accounts for 90 per cent of all uveal melanomas2. Two major cell types have been identified: spindle and epithelioid(2-4).
The COMS definition of melanoma for lesions less than 5mm in diameter (longest axis) and 1mm thickness, without associated risk factors, is a choroidal naevi (Table 2). However, distinguishing a benign naevus from a small melanoma remains challenging(3,5).
Table 2: COMS classification of tumour by size(3)
|Size height (mm)||Basal Diameter (mm)||Apical|
The risk factors identified in Table 1 should be carefully considered, and an ultrasound that shows low internal reflectivity and shifting of subretinal fluid, with positional changes of patient’s head, is also indicative of malignancy.
Tumours that fall within the COMS classification and smaller lesions with high risk factors should be referred to an ophthalmic oncologist for assessment. Treatment may include transpupillary thermotherapy, charged particle therapy, episcleral plaque brachytherapy or enucleation(2,3).
At the end of 2010 CFEH sent a reminder to all previous clients that one of the best gifts they can give a loved one is the “ability to prepare wisely for the future”… also known as foresight.
Family history is one of the strongest predictors of eye disease, but of course, many people mistakenly think that the vision their older relatives lose is an inevitable part of the ageing process, rather than a result of eye disease which can be halted if detected early enough.
Genevieve, a 28 year-old female, presented to her optometrist for a general eye examination to correct myopia. Her optometrist noted a small dark lesion on the left optic nerve and pigmentation in the temporal periphery of the right eye. She had LASIK four year earlier.
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.