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A new precedent in peripheral pathology detection

Optos’s ultra-widefield imaging systems are renowned for some of the most superior views of the retina, but the company recently went a step further to incorporate swept source OCT. DR DAVID SIA from Pennington Eye Clinic – Australia’s first practice to have Silverstone installed – discusses why it’s so beneficial for vitreoretinal specialists, ocular oncologists and beyond.

After completing dual fellowship training in the UK and Canada, Dr David Sia returned to Australia last year to begin working in private practice alongside his medical school mate Dr Weng Chan at Pennington Eye Clinic in North Adelaide.

Armed with fellowships in vitreoretinal surgery and ocular oncology – obtained from the Royal Alexandra Hospital, Edmonton and Moorfields Eye Hospital, London – Sia was keen to put his expertise to immediate use, supported with the most advanced imaging equipment.

Dr David Sia.

When Pennington Eye Clinic was established a few short years ago, it opted for the California system, Optos’s best ultra-widefield (UWF) retinal imaging device at the time. But the company soon developed a new device to incorporate swept source OCT (SS-OCT), leading to its most advanced instrument yet, Silverstone.

As an ocular oncologist, the system was an appetising prospect for Sia because for the first time ophthalmologists could easily capture OCT scans of peripheral lesions, which haven’t been readily achievable with traditional OCTs.

Late last year, his clinic became the first practice in Australia to install Silverstone. With the high costs of medical equipment, many practices easily become fixated on the return on investment or Medicare subsidies, but for Sia and Chan it aligns with their goal to provide optimal care for patients.

“I think having advanced imaging equipment with such high levels of speed, resolution and capability allows us to do so much more for our patients. It also provides extra information that really benefits the efficiency and workflow of our practice, along with the satisfaction of working here,” Sia says.

“With Silverstone, it’s incredibly useful to show patients what we are looking for. And performing swept source OCT over lesions that are far in the periphery is an
important function we wanted to add to our armamentarium of imaging.”

Top-of-the-range system 

Optos states that Silverstone is the most powerful tool yet for examining the retina. With it being the only device of its kind with integrated SS-OCT, it produces a 200° single-capture image – which it calls an optomap image – in less than half a second. OCT scanning can be guided across the retina and into the far periphery.

While the Silverstone is now officially available for sale globally, with cancellations of national congresses across Australia and New Zealand due to COVID-19, Optos has not officially launched Silverstone yet. But it hopes to do so later this year.

“In the meantime, sales enquiries and interest has been very high in our top-of-the-range device even prior to our official launch in Australia and New Zealand,” the company’s Australian managing director Mr Jason Martone says.

“Pennington Eye Clinic was the first practice to purchase and use the Silverstone in the country. Dr Chan and Dr Sia are big believers in the importance of providing their patients with the best possible care and were adamant that they have the Silverstone in their practice as it provides superior imaging for treatment, management and research relating to so many different conditions.”

Optos Silverstone.

While 82% of the retina is captured in the 200° optomap image – enabling eyecare professionals to see 50% more compared with the next closest imaging device – Silverstone also has an auto-montage feature that can allow up to 220°0of viewing, as well as image pairing for optic disc and retinal evaluation. More than 1,000 peer-reviewed studies are also said to show the long-term value of optomap imaging in diagnosis, treatment planning and patient engagement.

Now, with integrated SS-OCT that offers a line scan of up to 23mm, Martone says Silverstone facilitates cross-section examination of the retina from vitreous through the choroidal-scleral interface.

While Optos’s devices initially have been perceived as a tool for retinal specialists, the company says Silverstone should be viewed as an asset to general ophthalmologists and eyecare professionals due to its wide range of functions. The company has incorporated its entire suite of other imaging modalities; colour, red-free, choroidal, autofluorescence (AF), fluorescein angiography (FA) and indocyanine green (ICG) angiography.

For Sia, the OCT functionality has been most useful in common lesions like suspicious choroidal nevi. In recent years, stronger data has been published to show that multi modal imaging, particularly OCT over the lesion, is a key part of diagnosis and management.

“It shows us subtle subretinal fluid in peripheral lesions where conventional OCTs cannot reach,” he says.

“It also helps to delineate which level the lesion or pathology is at. For example, in congenital hypertrophy of the retinal pigment epithelium (RPE), a scan can show a thickened RPE and a normal choroid layer. It’s wonderful to be able to document that and educate patients visually with a scan. Other applications include areas of subtle pigmentary change and investigating abnormal vitreoretinal interface and traction.”

Ultra-widefield views 

With respect to Silverstone’s UWF imaging capabilities, Sia has been particularly impressed with the FA and ICG angiography modalities.

He says it’s made a significant difference in medical retina work up of patients with diabetes, vascular diseases and uveitis.

“UWF fluorescein angiography is also particularly useful in patients with Von Hippel–Lindau syndrome, where they get retinal capillary hemangioblastomas. In this condition, it is important to look for all lesions in the fundi, even the most minute ones and treat them early. The UWF angiography allows you to do that really well.”

With plenty of exposure to the California device during his fellowship training, Sia has been a long-time exponent of Optos’s UWF imaging systems. In addition to medical retina and ocular oncology, he sees several benefits for other ophthalmology specialities, particularly with its ability to capture such widefield images through most cataracts and small (2mm) pupils.

optomap FA of hemi-retinal vein occlusion, courtesy of Dr David Brown, Retina-Consultants of Houston, Texas.

“As a retinal specialist, we have most of our patients well dilated for a full fundus examination at each visit. Some practices may not dilate all their patients at each visit as dilation can affect the intraocular pressure and angle architecture,” Sia says.

“I think this is where Optos – being a scanning laser technology – has a huge advantage and is still able to obtain an ultra-widefield scan even through undilated pupils.”

Practice workflow 

Correct pupil dilation for a conventional fundus camera image can also consume valuable time in the clinic. Sia says this process can take around 15 minutes per case and when they’re ready, patients need to look to a particular position to be able to capture the area in the periphery.

“Even then you end up with multiple images that you have to stitch together to form a composite wide-field image to cover the entire lesion that you wish to monitor.”

Each incremental gain is important to the overall efficiency of the practice. At Pennington Eye Clinic, roughly 160 retina and oncology patients are seen each week.

Almost all are scanned with Silverstone in the work up phase. If they’re referred for a particular lesion, in the same sitting the operator will perform a SS-OCT over the lesion and macula before sending them for ophthalmic consultation. The clinic’s optometrist and ophthalmic technicians perform the scans, which has required minimal training and a small learning curve.

“Having all the imaging done right away, there’s minimal back and forth or changing between machines, and that really adds to the efficiency. When the patient is in my room, I usually have all the information I need at my disposal to diagnose and manage as well as have a detailed discussion with them about their care, with the images and scans.”

Before the patient is sent home, Sia says having such high-quality scans work as an important demonstration tool to have a comprehensive conversation with patients about their management or surgery. In turn, patients are fully engaged in their care and do appreciate the extra visualisation of their disease. It also helps to ease anxiety in many cases.

“It makes a whole world of difference to show them what we are looking for. Other conditions outside of ocular oncology include monitoring retinoschisis. Conducting an SS-OCT scan over the area to show the patient the splitting of the retinal layers, as well as the extent of the involvement is very helpful for their understanding,” he says.

“For pre- and post-images I can show them a retinal tear, and then after performing laser, I can demonstrate how it’s been well-surrounded.”

Looking ahead, as Optos’s global team seeks to continually improve of its entire suite of devices, Sia says he is excited about the direction the company is taking. n

NOTE: Dr David Sia and Dr Weng Chan have no financial disclosures and do not receive any benefits from Optos.

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