ENHANCED VIEW

Dr Paul Baddeley (left) and Dr Oliver Comyn assess retinal images at their St George's Eye Care clinic.

ENHANCING RETINAL PATHOLOGY DETECTION

UK-trained ophthalmologist DR OLIVER COMYN made it a priority to install a state-of-the-art imaging device when he joined a well-known private hospital in New Zealand as its sole retinal specialist. Now that piece of equipment has become an essential part of the clinic.

When St George’s Eye Care appointed Dr Oliver Comyn as its first dedicated medical retina specialist, it did so with the intention of expanding its suite of services beyond cataract and glaucoma care.

Comyn arrived at his new post in Christchurch, New Zealand, in 2018 having completed vitreoretinal fellowships at the Sussex Eye Hospital and the world-renowned Moorfields Eye Hospital in London, in addition to internationally published works on diabetic eye disease and retinal imaging.

For St George’s – the first private hospital in New Zealand to invest in fulltime ophthalmologists – it was an important appointment because it meant medical and surgical retinal treatment would become a significant component of the clinic, with Comyn complementing the practice’s other consultant ophthalmologist Dr Paul Baddeley, whom he trained under in West Sussex in 2013-14.

Imaging equipment is a key tool in the repertoire of any medical retinal specialist, so upon his arrival Comyn was determined to advocate for investment in a state-of-the-art instrument that would offer superior results and usability than the existing fundus camera.

That device was the Optos California FA ultra-widefield (UWF) retinal imaging device with optomap. After stating his case, the instrument was swiftly installed and has now cemented its place as a key piece of equipment.

“The hospital recognised in order to have a comprehensive and credible retinal practice we needed something to capture images and conduct fluorescein angiography, without the need to employ a retinal photographer who could use a fundus camera effectively. We also didn’t want to risk acquiring poorer images with the existing camera,” he says.

“Ultra-widefield images are essential to managing retinal disease today, and widefield angiograms and the ability to do targeted laser treatment based on identifying vascular changes in the peripheral retina is part of modern retina care, so my argument was if they were serious about having a retinal specialist who could treat all patients coming through the door then this was the piece of equipment to do that.”

EASY ACQUISITION

Optos California has been available to the Australasian market for five years and remains the company’s premium offering to optometry and ophthalmology practices.

It comes in three versions, with up to six imaging modalities including three-in-one colour depth imaging (colour, red-free and choroidal in a single image), as well as autofluorescence (AF), fluorescein angiography (FA) and indocyanine green angiography (ICG).

According to Optos, the California RG version has been popular among general ophthalmologists because it allows for high resolution 200° ultrawide field (UWF) colour and AF images of the retina, without the need for dilation, in as little as 0.1 seconds.

The mid-range California FA has the added benefit of UWF angiography to provide diagnostic information of the mid and far periphery for general ophthalmologists and retinal specialists.

California ICG incorporates the technology of the other two models plus interweaved ICG. This added feature is for retinal specialists to optimise management of AMD, uveitic conditions and other choroidal pathology.

According to Optos, up to 82% of the retina is captured in one

The Optos California UWF retinal imaging device offers up to six imaging modalities.

image, allowing eyecare professionals to see 50% more compared with conventional imaging devices such as the slit lamp, indirect ophthalmascope (30°) and fundus camera (45°).

Since arriving at St George’s, Comyn has grown the retinal patient cohort to fill one clinic out of four each week, with up to 14 patients. Many visit on a regular basis for injection treatments and he also performs retinal surgery at the hospital too.

In addition to the imaging benefits, Comyn says an important factor in choosing Optos California was its usability. It meant the clinic avoided the need for heavy investment in the upskilling of the existing ophthalmic technicians and clinic nurse.

In turn, the instrument could be used to its full capability soon after installation and removed the need for pupil dilation as is necessary in traditional imaging techniques.

“The fundus camera was rarely used before I arrived, and the staff weren’t particularly confident using it; they didn’t understand all the features and hadn’t had formal training as retinal photographers. I wanted the clinic to have a machine that enabled rapid and easy acquisition of images by the technical staff without the need for complicated training or further qualifications,” he says.

“Our staff have been impressed with how quick it is, it doesn’t have any complicated settings, it’s easy to use and acquires really good images. Patients also like seeing images of their eye.”

Further, Comyn says the review software is simple to use. It’s browserbased so images can be reviewed on any computer within the practice network.

From a disease management perspective, Comyn says the 200° fieldof-view is one of California’s greatest strengths, making it possible to view almost the entire peripheral retina with steered views.

“I think it’s important to understand that optomap images don’t replace clinical examination, but they complement it. It’s good for identifying peripheral retinal pathology, such as a small retinal tear you may have otherwise missed. It’s great for assessing how well you’ve applied laser. Sometimes patients can be difficult to examine, they can be light sensitive, blink a lot or they can struggle to get into the right position on the slit lamp for a detailed examination,” he says.

“It also combines photography, fluorescein angiography and autofluorescence imaging in a single machine. Autofluorescence is useful for looking at patients with retinal dystrophies, age-related macular degeneration and pachychoroid disorders like central serous retinopathy.”

As an example of its ability to expose hard-to-spot pathology, Comyn points to a case where an optometrist contacted him about their inability to perform an OCT scan on a patient. The optometrist sent an optomap image and it became clear why the OCT wasn’t functioning.

“The patient had a retinal detachment the optometrist hadn’t noticed on the Optos image. This one was quite shallow and the patient had lots of other changes in their retina that were distracting,” he says.

“It’s a great tool for communicating with optometrists and trying to identify whether the patients need to be referred to an ophthalmologist.”

Due to its ability to show the peripheral retina, Comyn says California is also useful for retinal vascular disease.

“For a case of branch retinal vein occlusion, it can show what you thought was perhaps a fairly small occlusion involving the posterior pole may actually involve quite an extensive amount of the peripheral retina, and you can demonstrate that by normal colour imaging or angiography, which shows a lot more than a fundus camera. This can improve patient care by allowing you to do targeted laser to areas of retinal ischemia.”

Also impressive, Comyn says, is California’s zoom function allowing detailed inspection of the macula, optic nerve head and small pathology. The sophistication of this technology includes a feature where the eyecare professional can take a portion of a historical scan and overlay that with the patient’s latest scan.

He says this had benefits in monitoring disease progression including retinal lesions and choroidal nevi.

“It allows for multi-modal imaging where you can drag a colour image over a fluorescein angiogram image; this allows you to localise angiographic changes such as leaking vessels with actual retinal landmarks,” he says.

EDUCATING PATIENTS

The ability to produce clear and detailed images is also said to be a powerful tool to educate patients.

This includes cataract patients, who make up a significant proportion of cases within St George’s Eye Care. Due to the swift image acquisition of California, retinal imaging has become a standard part of the cataract work up – a measure that would be unviable if a fundus camera was the primary imaging tool.

“We use the images educationally to show the effect the cataract might be having on the view of the retina and to show when there’s co-existing pathology – as there frequently is,” Comyn says.

“For example, if they have macular degeneration you can show them the features of the disease on the Optos image and explain how that might have an impact on the final outcome. We find patients really understand what we are talking about when we show them the actual changes in their eye, it makes it much more real rather than being a theoretical idea that they can’t visualise.”

Mr Anton Tesoriero, account manager at Optos Australia, says with three different versions, California has gone from being perceived as a retina specialist product to “must have” for eyecare professionals looking to enhance diagnostic capabilities, practice efficiency and patient experience.

“More than 900 published and ongoing clinical trials, as well as thousands of case studies and testimonials, show the long-term value of optomap imaging in diagnosis, treatment planning, and patient engagement.” n

USING MEDICARE

An additional 79,000 Australians are expected to develop glaucoma in the next five years, costing the economy $4.3 billion. Specsavers optometry director DR BENJAMIN ASHBY explains some of the strategic initiatives, including OCT and visual fields, in place to mitigate this problem.

Despite progress in the understanding of glaucoma pathophysiology, clinical technology, and optometrists’ training and scope as primary eyecare providers, 50% of Australians with glaucoma remain undiagnosed. This is often despite the fact many who likely have the disease have recently accessed eyecare. Ultimately, the undiagnosed glaucoma rate has remained relatively unchanged for the past three decades.

This is primarily due to the nature of glaucoma, with a lack of overt signs and symptoms in early stages and with functional deficits often preceded by extensive structural damage before they manifest in a way patients can notice.

According to Dr Benjamin Ashby, optometry director at Specsavers Australia and New Zealand, early detection of glaucoma is critical to preserving vision and maintaining quality of life for patients, as well as providing a more cost-effective method to lessen the burden of the disease on the economy.

As a part of its Transforming Eye Health strategy, Specsavers has collaborated with industry stakeholders to implement several initiatives within its practices to detect and refer those with undiagnosed glaucoma.

Following extensive investigation and piloting, Specsavers invested more than $40 million to rollout optical coherence tomography (OCT) and related training across its network from 2017. The approach was deliberately to use OCT as part of a standard eye test for all patients, harnessing the clinical benefits of this imaging technology to enhance detection of asymptomatic and early stage eye disease.

“OCT has been regarded as a supplementary test for glaucoma diagnosis by optometrists rather than a case-finding tool. Its systematic use on all patients has resulted in an increase in glaucoma detection across our population,” Ashby says.

According to Specsavers, consistent application of OCT as part of the optometric consultation, together with Optometry Benchmark Reporting, clinician education and adherence to the RANZCO Referral Pathways, has been effective in increasing the rate of glaucoma detection in line with published prevalence rates for the condition. The

Figure 1 – Glaucoma detection rates by age group from 2019 showing the impact of OCT.

graph in Figure 1 shows glaucoma detection rates as measured in 2019.

USING VISUAL FIELDS TO DETECT GLAUCOMA

OCT helps to facilitate the detection of glaucoma at a stage where visual field loss is minimal, allowing the greatest opportunity for patients to maintain vision and quality of life, Ashby says.

The enhanced visibility of the retinal architecture OCT enables has been beneficial in supporting optometrists to detect early nerve fibre layer and ganglion cell loss. Equipped with this information, Ashby says the data shows optometrists have been better able to make consistent decisions to perform clinically indicated visual field assessment, interpret structural and functional correlations and then refer for ophthalmological intervention appropriately.

“From the outset we have closely monitored the rate of visual field performance before and after introduction of OCT. This was, and continues to be, the clearest first indicator of whether the technology is enhancing identification of clinical risk factors for glaucoma and other eye conditions. We measure visual field rates at a national level all the way down to the individual optometrist in any one of our practices,” he says.

In addition to this, Ashby says it has been important to understand the link between visual field performance and detection of glaucoma.

“We first analysed the correlation between visual field performance and glaucoma detection in 2017 using a dataset of 5.3 million patient outcomes. At this time, we found the 13% visual field rate correlated with detection of glaucoma at the population prevalence (see Figure 2).

“Given the scale of the dataset and the gravity of what we had found, we made the decision to benchmark visual field performance as a point of reference, so optometrists could apply this in the context of the RANZCO Referral Pathways for Glaucoma with the aim of enhancing detection of glaucoma in their communities. This benchmark was a crucial step in drawing attention to the evidence and set a precedent as it was the first ever data-led benchmark derived for visual fields in optometric practice. Since then, we have repeated the analysis and the benchmark continues to be supported by the data.”

From an optometrist’s perspective, this means that if they are seeing 15 patients per day, statistically, one or two of them will require visual field testing on that same day and over a week, one or two patients will be referred for specialist follow up.

Detection of glaucoma at this rate does rely on optometrists assessing the eye both structurally and functionally, conducting visual field assessments for all patients where clinically indicated.

Ashby says Specsavers’ visual field monitoring also extends to analysing Medicare utilisation in the context of all eye health providers in Australia. The visual field trends being observed through the Medicare national dataset are reflective of the changes instigated by Specsavers in the past few years and directly correlate with increased glaucoma detection.

“Medicare funding of visual fields is an important public health lever to support detection and management of glaucoma in the community. It is vital that this government funding is used wisely to provide accessible clinical services that have a measurable impact on detection rates and effective comanagement of this endemic cause of avoidable blindness.

“Increasing rates of visual fields across optometry can only be seen in a positive light when it is linked to progress in detecting the 50% of undiagnosed glaucoma in this country. The real concern right now are the thousands of people at risk of glaucoma that have not had access to this service because of COVID-19.”

FALSE POSITIVES

Adaptions in the eye test process have led to increases in detection and referral rates for glaucoma, and a significant increase from 0.55% of patients referred for glaucoma in 2017, compared with 1.26% in 2019. Ashby says this understandably raises questions about false positive referrals.

“We have sought to confirm the appropriateness of glaucoma referrals and worked with e-referral platform Oculo and ophthalmologists across Australia to identify the rate of false positives following specialist assessment,” he says.

A process has been established whereby optometrists are required to classify referral types into one of three categories: ‘new assessment’ for patients who are newly diagnosed by the optometrist and have never been seen by an ophthalmologist; ‘suspect review’ for existing probable glaucoma suspects who are being monitored for progression but have not yet started treatment; and ‘glaucoma review’ for patients with existing confirmed glaucoma.

Ophthalmologists can provide one of three diagnoses after the patient’s attendance through Oculo: ‘glaucoma’, ‘glaucoma suspect’ for patients in

Figure 2 – Data from more than 1,400 optometrists reveals a strong correlation between visual fields and glaucoma referrals.

Figure 3 – Ophthalmology feedback on new glaucoma referrals.

whom glaucoma was probable but not confirmed, or ‘no glaucoma’. The percentage of patients who received a diagnosis of ‘no glaucoma’ is used to determine the false positive rate. Ashby says Specsavers has now received feedback on a subset of 784 Australian patient referrals. Of the patient referrals for newly detected glaucoma, 79% were confirmed to have definite or probable glaucoma (see Figure 3).

Glaucoma surgeon and neuro-ophthalmologist Associate Professor Mitchell Lawlor from Sydney Eye Surgeons and Macquarie Street Eye Surgeons, has contributed to the emerging feedback data.

“The process of capturing and reporting on ophthalmological feedback is crucial in verifying the increasing glaucoma detection rate. Feedback on appropriateness of referrals is key to driving systematic change that ensures the right people are referred at the right time for early treatment of glaucoma.”

Ashby says while the ongoing importance of collecting feedback data is acknowledged, this initial set of outcomes compare favourably to prior studies of optometric glaucoma referrals where up to 58.3% resulted in a ‘no glaucoma’ diagnosis at the first specialist visit.

“This suggests that our systematic use of OCT has lifted detection rates of glaucoma whilst maintaining comparably high levels of referral accuracy and appropriateness.” n