Optical coherence tomography (OCT) offers optometrists and ophthalmologists more clues to spot a cancerous malignancy in the eye, Royal Liverpool University Hospital ocular oncologist, Professor Heinrich Heimann, told attendees at the National OCT Conference (20–21 November, Hilton Birmingham Metropole).
The topic of appropriate diagnosis of life-threatening conditions is particularly relevant for the profession in the light of the Honey Rose trial in July.
Professor Heimann outlined the most common mistakes that primary care providers make, from failing to examine under the lid of the eye to failing to examine the periphery of the retina during an examination.
He also emphasised the importance of photo-documentation, adding: “Please, please, please try to get a photograph.”
The other frequent mistake is when a patient becomes lost in the system when requiring a follow-up. Professor Heimann advised optometrists to repeat to patients to re-contact the hospital or the practice if they experience delays.
However, Professor Heimann explained that just one naevus in 40,000 will turn into melanoma. “While you have to follow up, don’t overestimate the risk. Most of them are never a problem,” he highlighted.
Professor Heimann reviewed the nine risk factors of a naevus being a cancerous growth, and the role that OCT can play in helping an optometrist to assess the need for a standard or urgent referral rather than continued, six-monthly checks.
Six risk factors
- Visual symptoms, such as vision loss or flashing lights
- Thickness of more than 2mm
- Proximity to the optic disc
- Low reflectivity on ultrasound
- The absence of drusen
- The absence of a halo around the lesion.
Three key risk factors
- Sub-retinal fluid
- Orange pigment, that may be grey or brown in a white tumour
- Documented growth.
While many of these risk factors could be distinguished by ophthalmoscopy, OCT, particularly swept-source OCT, offered extra information to optometrists who encountered a suspicious lesion, Professor Heimann reiterated.
Scans could help practitioners to easily determine the thickness of a lesion, distinguish between a tumour and scleral thinning or retinal pigment epithelium detachments, as well as localise which layer of the retina that a growth is in, delegates heard.
OCT is also able to give a clinician clues as to the lifespan of a tumour, evident from the health or degradation of the retina.
Additionally, the scanning systems enable a practitioner to better pick up retinal fluid, Professor Heimann explained, continuing: “This is where the OCT really shines.”
He advised optometrists to image the fovea as well as the lesion area, as fluid could build up away from the site of concern.
OCT could also highlight indications that warranted further action, such as cases of patients with epiretinal membranes, which illustrate that the periphery needs to be assessed, he said.
However, he also warned that OCT had some limitations, for example, the scans are not able to penetrate far into dark-pigmented lesions.
Professor Heimann invited optometrists wanting to further develop their imaging, diagnosis and management skills to attend his upcoming Royal College of Ophthalmologists’ event in July.
Top tips for OCT beginners
Morven Campbell, clinical services manager for Black & Lizars
Prepping the patient. Advise a patient to take a nice, big blink during the scan countdown and then to stare straight ahead, looking at the fixation target. This will ensure a stable tear film and a clearer image. It will also make the patient less likely to blink during the scan.
Explaining the system. The 3D display option has limited clinical importance, but patients can find it easy to comprehend. It can be good to impress upon them that the scans are something that they may not get at every opticians.
Go black and white. Once you have become familiar with the appearance of the retinal layers on OCT, remove the colour filter. Viewing OCT in black and white generally shows greater resolution of detail.
Refer appropriately. Understand that you will see some conditions, such as vitreoretinal traction, macular holes and epiretinal membranes quite commonly, so it is best to ensure that you keep risk factors, untreated resolution rates and treatment options and risks in mind when choosing to refer or monitor.
Develop peer relationships. Relationships with other optometrists with OCT expertise or ophthalmologists to share complex cases with can be a great help. Familiarise yourself with the ways that you can share or email results and scans for a second opinion, but be careful about sending confidential patient details without prior permission.
Promote warning signs. If you want to monitor a patient with regular checks rather than referring them, be sure that they are familiar with the symptoms that they should look out for.