Pan European Networks - Horizon 2020 - page 37

The images are open to more sophisticated manipulation than simple
2D photographs, but in essence they are no different in the hands of the
optometrist to any other tool that provides data which can be used in
different ways. For example, a fundus camera produces an image which
then requires interpretation. It is what one does with the data or image
that is dependent on the jurisdictional capability of the optometrist.
The taking and possession of an OCT image is in no way different
philosophically to the recording of fundal information on a record card
or the recording of tonometry data, with the exception that it can be
archived and communicated more efficiently. In some instances, the
optometrist uses the instrument to establish the normality of the patient
under examination, as per any other examination tool. The OCT in this
context would provide corneal thickness measures in keratoconic lens
fitting and can be used to exclude a non-optical cause of reduced visual
acuity (e.g. due to common retinal abnormalities of the epiretinal
membrane) or to confirm the urgency of a referral in wet ARMD.
In jurisdictions where optometrists are legally obliged to exercise
diagnostic judgement before referral, for example the United Kingdom,
OCT is invaluable in determining urgency and appropriateness of referral
and, in fact, to whom the referral will be directed. OCT represents a major
scientific advance that has the capacity to assist public health systems
in streamlining referral. The instrument needs to be in common use in
the primary healthcare arenas and not be restricted to a referred
secondary or tertiary service.
It is no more possible to say that an asymptomatic patient seeking
refraction has no likelihood of clinically significant lesion visible on OCT
than it is possible to say that asymptomatic people over 40 do not need
tonometry or visual fields. Within ten years, OCT and other devices, such
as OPTOS scanning laser ophthalmoscopes, will have completely
replaced fundus cameras and rendered ophthalmoscopes obsolete.
in both ophthalmoscopy and fundus photography,
only a 2D view of the retina is possible.
Consequently, this makes it extremely difficult
to correctly assess where swelling or oedema
is present, which can lead to false positive and
false negative screening results.
The technology used in OCT examination offers
the examiner a different perspective when
visualising the retina. In essence, OCT provides
a 3D image of ocular structures, thereby
making it invaluable in the proper identification
of conditions where there may be swelling,
oedema or other damage in the retina. Early
identification, and therefore early treatment, is
vital in order to avoid preventable sight loss.
Case finding by optometrists plays a significant
role in the healthcare pathway, ensuring that
patients are directed to secondary and tertiary
medical care in an appropriate and rapid
fashion. OCT imaging used in optometric
practice is an extremely useful tool in case
finding for a variety of ocular conditions where
other examination and imaging techniques may
be inadequate.
Case finding, by definition, does not constitute
making a diagnosis but simply the identification
of clinically significant ocular findings. The use
of OCT as a referral refinement tool can
significantly reduce the incidence of both false
positive and false negative results. Whether an
optometrist makes a diagnosis based on an
OCT scan or refers to medical diagnosis and/or
treatment is a matter for protocols to be agreed
based on relevant national statutes.
OCT operation
In operation, the technical skill required in 3D
Fourier domain OCT appears little more than
that required to operate a digital fundus
camera, whilst in many hospitals, images are
taken by technicians. In fact, the skill is
greater as the images can be prone to
alignment and artefactual errors. In some
cases, dilation is required to achieve optimum
results. Optometrists have the skills to
operate an OCT efficiently with minimal
training, unlike a technician.
Martin O’Brien
European Council of Optometry and Optics
Nick Rumney
General Optical Council
B R OW S E
H O R I Z O N
2 0 2 0
H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L
I S S U E S I X
37
O P T O M E T R Y
OCT of a retina
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