Author: Dr Mary-Ann Sherratt MCOptom, College President
Date: 3 October 2017
For over a decade, clinically forward-thinking practitioners have been performing OCTs in the primary care setting. Three generations of OCT have come and gone in that time, various models of delivery have evolved and are evolving still, with fee structures varying from the fully inclusive within the eye examination to significant additional payments. Many practices list the numerous benefits of offering OCT, some of which may include improving the clinical profile of the practice, rendering it more attractive both to patients and clinical staff, and improving the ability of a practice to work and interact with ophthalmology departments. However, the journey has not been without its bumps. Early adopters found that OCT resulted in novel clinical findings with no clear management pathway, some medical retina departments faced an increase in false positive referrals, and there has been a mixed response by the public to paying for additional diagnostic tests, along with the introduction of the ethical dilemma presented when a patient whose presenting symptoms require an OCT declines a scan because of the cost.
False positive referrals can be attributed a number of factors: seeing a wider range of essentially normal findings in a new way, such as vitreoretinal traction or early drusenoid changes; and artefacts and misinterpretation of either the image or the normative values (‘reading red’). However, with experience and some training rather than referring more pathology, optometrists anecdotally report referring more accurately, and in some cases, fewer nonprogressive pathologies once they are experienced in interpreting the results. The consequence of increasing sensitivity and specificity where there has been adequate training is frequently the reduction of unnecessary referrals, helping to hone referrals and aiding effective triage decisions. For example, OCT can be used to identify wet AMD, removing the need for referral for the majority of symptomatic dry AMD cases. The lesson learned from the past decade is that initial education and ongoing clinical training is essential to the successful launch of an OCT service. Credit must be given to OCT manufacturers who have all greatly stepped up the quality and quantity of resources available to practices starting an OCT service. Ten years ago, practitioners would be lucky if they had access to a pathology atlas, whereas now online training, lecture series and conferences are the norm, with some suppliers making training a pre-requisite to purchase.
Early adopters found that OCT resulted in novel clinical findings with no clear management pathway.
It is an established principle in medicine that you should only perform a diagnostic test where is it clinically indicated: this is stated in section 7.6 of the GOC Standards of Practice and section D3 of the College’s Guidance for professional practice. The overuse and indiscriminate use of diagnostic tests in any field of medicine increases false positive referrals, results in avoidable distress to patients, and wastes resources. Any diagnostic test used should be supported by evidence and be free from harm, shouldn’t duplicate other tests, and should really be needed. OCT is supported by evidence, doesn’t duplicate information, and is free from direct harm, so is it is really needed as part of a routine sight test? Where there is a clear clinical indication, such as a suspicion of wet AMD, then OCT is a valuable addition to diagnostic decision making, but what about routinely assessing the eye using an OCT while making an initial ‘baseline’ review on asymptomatic patients?
There is an interesting discussion to be had as to whether an OCT is always an additional diagnostic test used according to clinical guidance, or whether an OCT assessment is now part of the natural technological progression of assessing the eye and should be open to as many people as possible without specific clinical justifications. Section A35 of the College guidance states that the optometrist should use their professional judgement to decide the format and contents of the tests performed during an eye examination. An optometrist could reasonably conclude a baseline OCT examination aids the detection of disease and abnormality, particularly in relation to subtle or historical macular changes such as macula odema or vitreoretinal traction. In glaucoma, imaging is at its most useful in the assessment of the optic nerve head and retinal nerve fibre layer when baseline information is available.
Twenty years ago, the mainstay device for ocular assessment in an optometry practice was the direct ophthalmoscope, whereas binocular indirect ophthalmoscopy is now widely accepted as the primary method of clinical assessment alongside fundus photography: technology has enhanced our ability to deliver better care to everyone as standard. Is OCT the next logical step to become part of what we will in the future consider a standard ocular assessment?
Over the last decade there has been much variation in the language and terms used to describe imaging technologies including OCT, with variation in the claims made regarding the potential benefits of each one. As a member of the public, it is likely to be easy to confuse regular retinal photography, widefield scans such as Optomap, and OCT. The language and marketing communications used to promote and explain OCT should be carefully considered and balanced. Potential benefits should not be overstated and traditional methods or techniques should not be automatically criticised or considered to be of lesser value.
The wide scale adoption of OCT is potentially good for the public and is certainly exciting for the profession. As we have already seen, its success will be heavily influenced by the quality of education, training and experience of the optometrists using the more recent technology, and the detail of how it is used. Ultimately, if progress in technology is to benefit the patient, investment in quality assured training supporting the ability to make value judgments is as important as the significant investment that must be made in the instrument itself.
Technology has enhanced our ability to deliver better care to everyone as standard. Is OCT the next logical step to become part of what we will in the future consider a standard ocular assessment?
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