Recruitment

The staged nature of the trial and the risk of withdrawals (most, but not all, participants progressing from training to the main trial or withdrawing for other reasons) combined with the priority of maintaining the balanced incomplete blocks design made recruitment challenging, particularly given the short duration of the trial. The balanced incomplete blocks design meant that each participant had to be assigned a specified set of vignettes for the main trial assessment on completion of webinar training. This constraint prevented an extra participant from being recruited until an existing participant had definitively withdrawn. As participants could not all be recruited at the same time and progressed at different speeds, we did not know until a considerable time had elapsed whether or not additional participants would be needed. In order to expedite completion of the trial, we reopened recruitment at a later stage and deliberately over-recruited participants to the webinar training, some of whom did not progress into the main trial because the target sample size had been reached. Close to the end of the main trial, in order to increase the likelihood of completing the main trial in accordance with our revised schedule, we also assigned two participants to one set of vignettes in order to be more confident that at least one would complete the assessments promptly.

The need to over-recruit also had financial consequences for the trial budget. Participants who chose to withdraw during their participation in the trial were paid only for the time spent on webinar training and not for any training or main vignette assessments that had been carried out up to the time of withdrawal. However, those participants who were withdrawn by the trial team, either because of failure at the training stage or because the trial had reached its target, were reimbursed fully up to the point of withdrawal, as if they had completed the study.

Images used to create vignettes and constraints on viewing images

Despite the overall size of the IVAN trial image repository, the number of suitable baseline and index images available to create vignettes was much smaller than anticipated. This limitation required us to identify a different combination of (1) number of participants, (2) number of vignettes per participant and (3) number of times each vignette was assessed. The final design recruited 96 participants (48 in each professional group), each of whom assessed 42 vignettes, with each vignette being assessed seven times (by each group), requiring a total of 288 vignettes and 4032 assessments. This total was considerably smaller compared with our original plan for 96 participants each to assess 48 vignettes, with each vignette being assessed four times, which would have required 1152 vignettes and 4608 assessments.

The smaller number of available vignettes also forced us to sample sets of training vignettes from among the 288 vignettes used for the main trial assessments. This constraint meant that extra participants (recruited when recruitment reopened) could not start their training assessments until an earlier participant had withdrawn and freed up a specified set of vignettes for the main trial assessment.

All images used to create vignettes were reviewed by a senior grader from NetwORC UK (AM) and a retina specialist (UC) to identify appropriate pairs of sufficient quality. Almost all of the CF photographs in the IVAN trial repository that were potentially suitable for inclusion were considered to be of sufficient clarity and focus for constructing the vignettes. However, OCT images were subject to several limitations:

• We made the decision that vignettes could only be constructed with OCT images captured by spectral domain tomographic equipment. Spectral domain OCT systems provide images of greater clarity, resolution and definition and represent systems to which clinicians and optometrists are currently exposed. These spectral domain systems came into widespread use in 2008. When the IVAN study started in 2007/8, the standard for clinical trials was time domain OCT because the data import and export protocols and grading methods had been established and validated only for these acquisition systems. Therefore, the majority of sites in the IVAN trial used time domain systems to capture OCT images. Nonetheless, as the old time domain systems began to fail, most IVAN trial clinical sites replaced these with spectral domain systems. Validation of the spectral domain systems for trials was undertaken and, therefore, spectral domain OCT images were permitted in the IVAN trial protocol. Approximately one-third of all IVAN trial participants had OCT images acquired on one of the three types of commonly used spectral domain systems (Heidelberg Spectralis^®; Zeiss; Optovue). All the spectral domain systems yielded high-quality images. However, the lower aspect ratios of the Zeiss and Optovue made it more difficult to interpret images than with the Spectralis. This is because the appearance of the Spectralis images is more similar to that observed on a standard retinal histological preparation. The Spectralis is also in more widespread use in the UK. Both experts and participants commented that OCT images from the Zeiss and Optovue spectral domain systems were unfamiliar and, therefore, that the images were more difficult to interpret and that they were less certain about their assessments.
• Baseline and index OCT images consisted of six radial line scans which passed through the fovea. Ideally, scan lines at the same clock-face orientations should be captured at every visit and be displayed in the same order so that an assessor can compare the appearance of the retina at specific locations. For some of the scans, the orientations did not match exactly for baseline and index images.
• The web application presented ‘thumbnail’ images of all six OCT images and an assessor could ‘click’ on an image to enlarge it and to toggle backwards and forwards between the six enlarged images. (The website www.echoestrial.org/demo shows how assessors carried out assessments in the trial.) However, it was not possible to view baseline and index images for corresponding orientations simultaneously because of the limitation of providing the application on a single monitor. Paired viewing of OCT images is a desirable feature and it is usual practice for clinicians to use a paired display which allows the viewer to scroll through the different scan orientations from two visits on a single screen. One participant (Optom268, see Chapter 3, Participants’ views on ECHoES trial training) achieved this by having one set of images on a tablet and one set on a conventional computer display.

Reference standard

The original plan (described in the grant application) was for the reference standard to be derived directly from grading data collected during the IVAN trial. For various reasons, this was not considered acceptable once we started to set up the study: there are occasional errors in the grading data and the list of features/questions drawn up for the web assessment (see Table 2) did not completely match the table in the protocol or the grading data available. There were two key differences, namely (1) the distinction between presence of a feature in the index OCT and whether or not an increase in the feature had occurred from the baseline to the index OCT, and (2) the inclusion of DRT as a feature. Grading data were used to select baseline and index OCT pairs that were likely to suitable, based on the features described in the table in the protocol, but it was decided that the reference standard should be assigned by expert ophthalmologists (reading centre leads, UC, TP and SPH).

This decision was taken when the first draft of the assessment part of the website was available, in late June 2013. We accepted that training could begin while vignettes were being assessed by experts. However, there was still insufficient time for the three experts to assess each vignette by the time participants’ responses to the training vignettes had to be scored. Instead, we aimed for two experts to assess each vignette (one-third of the total number of vignettes by each pair of expert ophthalmologists), but only had one assessment for each vignette at the time that participants’ responses were scored. These assessments were carried out by two of the three experts.

As participants’ assessments on the training vignettes accrued, it became clear that there were some vignettes that participants were getting consistently wrong. Consequently, the two experts who had provided the expert assessments reviewed about 30 vignettes. Some of these were believed to be mistakes (mainly key-stroke errors when completing the web data entry) by an expert and the overall assessment was changed for 10 vignettes. These new gradings were later used in the derivation of the reference standard.

Classification of lesion activation status and lesion components

Optometrists were non-inferior to ophthalmologists with respect to their overall ability to classify lesions correctly: that is, the primary outcome. Neither group attained the level of performance expected at the outset (on which the target sample size was calculated). However, optometrists made different kinds of errors. Compared with ophthalmologists, it was less likely that they would classify a reactivated lesion as quiescent or suspicious (false-negative misclassifications) and more likely that they would classify a quiescent or suspicious as reactivated (false-positive misclassifications); better sensitivity, worse specificity. It is probable that this finding arises because optometrists tended to adopt a more cautious decision criterion, which would be consistent with their obligations under the General Optical Service contract (to refer any suspected pathology). The finding may also reflect the fact that optometrists had more difficulty in interpreting the diversity of appearance of quiescent lesions, that is, eyes with an abnormal appearance but not needing treatment, which are normally managed in the HES.

The poorer than expected overall performance may have arisen because the quality of the images was suboptimal. In a real-life scenario, any monitoring review (carried out by either an ophthalmologist or an optometrist) is likely to include examination of the patient, for example slit-lamp biomicroscopy, as well as review of CF and OCT images. Some components, such as blood and exudates, might be identified more reliably from this examination than from images. If this were the case, the combination of the vignette information with direct examination would increase the performance.

No harms could arise in the trial itself because all of the decisions being made were for anonymised vignettes. However, the health economic evaluation carefully considered the costs and consequences of the different types of error predominantly made by each group. In the context of community optometry, it seems desirable that optometrists should use a cautious decision criterion for referral, although this limits the potential benefit of the shared care model in terms of both the impact on workload in the HES (because of false-positive referrals) and its potential cost-effectiveness.

Optometrists were also non-inferior to ophthalmologists with respect to the frequency of false-negative sight-threatening errors (i.e. failure to identify a lesion as reactivated). In fact, optometrists were slightly less likely than ophthalmologists to make such errors because of their tendency to adopt a more cautious decision criterion. Conversely, optometrists made more non-sight-threatening errors (false-positive errors, i.e. failure to identify a lesion as quiescent or suspicious) than ophthalmologists.

Except for PED (which did not inform the classification of lesion activity), lesion components were identified as present more often by optometrists than by ophthalmologists, again consistent with optometrists adopting a more cautious decision criterion. This tendency was particularly evident for DRT and exudates. Ophthalmologists were much more confident in their classifications than optometrists. However, there was no association between confidence and the odds of classifying a lesion correctly. For all grades of confidence in the classification, optometrists had slightly better odds of classifying a lesion correctly. As hypothesised, other items of information included in a vignette did not influence participants’ lesion classifications.

The sensitivity analysis found a statistically significant difference, but not clinically important one, with respect to the prespecified non-inferiority margin, in favour of ophthalmologists. The alternative definition of the primary outcome used in this analysis involved reassigning four cells from Table 3. Participants’ classifications changed from incorrect to correct for two cells (suspicious reference lesions classified as reactivated by participants and reactivated reference lesions classified as suspicious by participants) and from correct to incorrect for two cells (suspicious reference lesions classified as quiescent by participants and quiescent reference lesions classified as suspicious by participants). Of these, the latter were both the most numerous (380 out of 4032 participants’ classifications) and showed the greatest difference in frequency between ophthalmologists and optometrists (88 more such classifications by optometrists considered incorrect in the sensitivity analysis; see Table 7). Reactivated reference lesions classified as suspicious by participants were second most numerous (338 out of 4032), with the difference in frequency going in the opposite direction (54 more such classifications by ophthalmologists considered correct in the sensitivity analysis). Both of these changes favoured the performance of the ophthalmologists. The large number of quiescent reference lesions classified as suspicious by optometrists almost certainly arises from their tendency to adopt a more cautious decision criterion. It is not obviously the case that it would be desirable to encourage optometrists to shift their criterion to a less cautious position, that is to ‘trade’ an improvement in specificity for a reduction in sensitivity, given the potential sight-threatening consequences of false-negative errors. The desirability of shifting the criterion would depend on the likelihoods of (1) reactivation being identified by the optometrist at the next monitoring review (when relevant lesion components are likely to have increased) and (2) irrecoverable sight loss from deterioration of the lesion.

The time taken to assess vignettes decreased as participants worked through their assessments for the main trial, and this finding was particularly marked for the optometrists. Interestingly, the time taken by optometrists more than halved and approached that taken by ophthalmologists by the time they reached their final assessment (2 minutes 31 seconds compared with 1 minute 55 seconds). This information gives some indication of how quickly optometrists can become proficient in assessing CF photographs and OCT images. We also investigated whether or not the time taken was associated with the odds of a correct assessment and found, in both professional groups, that a correct lesion assessment was more likely with a shorter assessment duration. This finding suggests that duration of assessment may have been a proxy for difficult assessments.

Data about the agreement between expert medical retina consultants represent a bonus from the study, as such data have not previously been reported. (These experts are responsible for the three sites that together make up the UK Network of Ophthalmic Reading Centres.) All three experts assigned congruent lesion classifications to over three-quarters of vignettes and disagreed completely (all three experts classified a lesion differently) for only seven vignettes. The level of agreement judged on the basis of kappa values (see Table 14) varied by lesion component; it was excellent for SRF, IRC and blood but poor for exudates and DRT. (Experts agreed about the presence or absence of exudates of > 90% of vignettes but the kappa value was low because exudates were rarely present.) These data emphasise several important points. First, the assessment task was difficult and was sometimes compromised by the images that were available (see Images used to create vignettes and constraints on viewing images). Second, signs of reactivation inevitably spanned a continuum and hence there was a need to assign a reference classification of suspicious for some vignettes. Third, the vignettes created from the IVAN trial repository represented a real-world spectrum of reactivation that was appropriate for the ECHoES trial.

There are no similar studies with which to compare our data and, consequently, no meta-analysis combining our findings with previous findings.

It is difficult to assess the extent to which the performance of participants is representative of the performance of the two professions and, hence, the applicability of the findings. Models of shared care for other eye conditions have been voluntary. Indeed, it is difficult to conceive a model in which optometrists, who are private practitioners, might be required to provide shared care. Our recruitment methods sought volunteer optometrists, presumably who were interested in shared care, albeit in the context of a research project. We cannot be sure that our recruitment methods for optometrists were generally applicable but can imagine that similar methods might be used, for example by clinical commissioners seeking to commission shared care in a particular geographic region. The motivations of the volunteer ophthalmologists were less clear, but a similar interest in the feasibility of shared care for nAMD is a possibility. The key question is whether or not volunteer ophthalmologists might have been less than averagely expert/experienced – or optometrists more than averagely expert/experienced – compared with the kinds of people who might volunteer for shared care. We think that this is unlikely but have no evidence to substantiate this.

For the findings to be applicable, the vignettes used for the study also needed to be representative of the clinical circumstances that community-based optometrists would be likely to encounter. In this respect, we are more confident that the study findings are applicable. The IVAN trial was pragmatic and had broad eligibility criteria. It recruited participants on presentation and followed their progress in the trial. Although their treatment was specified by their experimental allocation, all treatment regimens had similar effects on vision and morphology which were consistent with clinical experience and other trials of anti-VEGF drugs. Decisions about the need for retreatment had to be made in the IVAN trial just as in usual care. The availability of spectral domain tomographic equipment was limited by hospitals and clinic scheduling.

Health economics

The results of the economic evaluation show that, when we take account of downstream costs (e.g. follow-up consultations and injections), the optometrists had slightly higher costs and made slightly fewer correct retreatment decisions compared with ophthalmologists when performing the virtual monitoring review for the ECHoES trial. However, the differences were very small (an incremental cost of £13/consultation and one additional incorrect decision per 101 reviews conducted) and the differences were not significantly different.

Views of patients and health professionals about the shared care model

Overall, the findings show there was consensus that optometrists monitoring quiescent nAMD in the community have the potential to reduce clinical workload and could represent a more patient-centred option for patients. However, a number of potential barriers were identified which could limit the feasibility of a shared care scheme, including ophthalmologists’ perceptions of optometrists’ competence, the need for clinical training, whether or not optometry and ophthalmology could work more collaboratively and whether or not shared care was a financially efficient option for CCGs.

Participants felt that hospital eye clinics were pushed to the maximum capacity with the volume of patients who required care for nAMD. Research has found an insufficiency of resources to deliver nAMD secondary care from the burden of follow-up visits required in patients with inactive nAMD.¹² Therefore, the health professionals agreed that shared care would relieve the ophthalmology workload. Shared care schemes are also attractive to patients who would find it more convenient to be monitored closer to their home.^34,35 In line with previous research, the service users described how they were frustrated at the lack of support and information that they had received about their condition.^36,37 Consequently, they felt that being monitored in the community would enable them to build up a relationship with one optometrist, with whom there would be more of an opportunity to receive better support and information.

While most participants felt that motivated optometrists would be capable of monitoring patients, several ophthalmologists and service users were unsure whether or not the expertise of an optometrist in detecting reactivation of nAMD would be equal to that of an ophthalmologist. Previous research exploring perceptions of shared care for glaucoma has found that specialists are not convinced of optometrists’ expertise, even when they have received additional training.³⁸ Furthermore, interviews with service users who had declined to take part in a shared care scheme for a range of eye diseases (including nAMD) did so because of their familiarity with, and the reputation of, the HES.³⁵

Overall, the health professionals described poor collaboration between community optometrists and ophthalmologists working in the HES. Many participants, particularly the ophthalmologists and service users, voiced concerns about a potential delay between primary and secondary care if retreatment was required. This is a new finding, as previous research exploring patient perceptions of shared care for a range of eye conditions has not found this to be an issue.^34,35,39,40 Long-term research has demonstrated that recurrence of neovascular activity is common,¹⁵ and any delay beyond the recommended interval may cause patients to unnecessarily lose vision permanently.¹² Given that vision can deteriorate in a short time if nAMD is not treated and the potential impact this could have on independence and quality of life for patients, it is perhaps not surprising that receiving prompt treatment is an important priority for nAMD care.

The health professionals felt that, although virtual training could provide a foundation level of knowledge, clinical experience under the supervision of an ophthalmologist would be a more effective method of training. Shared care research for a variety of eye conditions has reported that, although web-based training is a convenient and effective option, it is not representative of clinical practice and may not be appropriate for teaching practical clinical skills which need to be developed through attendance at a training course.^35,41 Health professionals in the current study also highlighted that face-to-face training of this kind would provide reassurance to the ophthalmologists that optometrists were being trained to a high standard and further encourage interprofessional collaboration.

The health professionals considered the financial implications of moving to a shared care model, although commissioners appeared to experience conflict between what was best for the patient and what was financially efficient. There was also agreement that optometry practices may struggle to obtain appropriate equipment, but there was uncertainty as to how funding for OCTs would be provided. In line with this research, studies exploring optometrists’ perspectives of extending or enhancing their roles has highlighted a conflict between the retail and clinical sides of the optometric practice.^41,42 Amoaku et al.¹² points out that the technology involved in monitoring nAMD, particularly an OCT, is expensive and optometrists would be unlikely to receive any grants for their purchase. An additional financial consideration was that there could an opportunity to save money with a reduced fee for optometrist rather than ophthalmologist monitoring, although commissioners expressed concerns about the possibility – and subsequent cost – of repeat testing by ophthalmologists who doubted optometrists’ judgements when a patient was deemed to require retreatment.

In summary, the qualitative research demonstrates enthusiasm for shared care for nAMD. However, ophthalmologists and patients would need reassurance that greater convenience would not compromise the quality of care, in terms of both optometrist competence and the speed of the referral pathways back into secondary care if retreatment was deemed to be necessary. The research highlighted poor communication and trust between ophthalmologists and optometrists, and there was agreement that, if shared care were to be implemented, it would be essential that the two professions work more collaboratively. Training for optometrists under the supervision of ophthalmologists was deemed to be the most effective method of training and could improve the communication and trust between the disciplines.

Classification of lesion activation status and lesion components

The virtual nature of the trial element of the ECHoES study made it feasible to address the research question when a conventional trial may not have been feasible, either because of reluctance by patients or the professions to participate or because of the high cost of a conventional trial.¹⁹ We were able to carry out the trial within a relatively short period of time and at low cost compared with a conventional trial of the research question, and the study design did not require any compromise with respect to the risk of bias. Participants engaged extremely well with the tasks that they were set, evidenced by the trial having complete data for the analysis population and the level of participation in additional tasks not communicated to participants at the outset, for example questionnaires about training and the likely resources needed to provide shared care in community optometric practices.

There are two limitations that may be perceived to be critical, namely the virtual nature of the trial itself and the adequacy of training. A critic might argue that decision-making on the basis of a vignette bears no resemblance to face-to-face decision-making in a HES clinic. However, decision-making on the basis of investigations made previously, in the absence of the patient, reflects quite well how some hospitals are managing their workload by implementing a two-step process. Patients are first recalled for a monitoring appointment to capture BCVA and retinal images (usually staffed by non-medical personnel); the information is then reviewed in an ‘offline’ assessment by an ophthalmologist or other trained member of staff, and the patient is rapidly recalled for treatment if required. In our view, the task of vignette assessment in the ECHoES study closely parallels this offline assessment in the HES.

The importance of training was highlighted by identification of concern about the competence of optometrists as a potential barrier to implementation (see Chapter 5, Perceptions of optometrists’ competency). The quality of the training was perceived to be good, very good or excellent by over 90% of ophthalmologists but by only about 70% of optometrists; 70% of ophthalmologists considered that the training was sufficient, compared with only 20% of optometrists; and almost all optometrists, but only half of the ophthalmologists, revisited the webinars (see Chapter 3, Participants’ views of ECHoES trial training). These simple responses to the questionnaire items eliciting feedback about training were supported by free-text comments. These differences in perception about training are likely to have arisen for various reasons: some ophthalmologists may have considered themselves to be already trained; the training was inevitably conceived by ophthalmologists from a HES perspective; and the relative unfamiliarity of the task for optometrists may have made them less confident about the competence that the training had in fact conferred. Both the feedback questionnaire and the qualitative research suggest that a bigger investment in training would be required if shared care were to be implemented. The nature of further training that would address the need voiced by optometrists is unclear.

The nature of some of the images available to create the vignettes and the method for viewing OCT images were also potential limitations of the study (see Images used to create vignettes and constraints on viewing images). These limitations may explain in part why the performance of ophthalmologists was worse than expected (about 85% correct compared with the expected 95%). Consequently, the performance levels observed in the trial should, perhaps, be considered to be the minimum achievable. It is possible that ophthalmologists (most of whom were already familiar with OCT images) could have been selectively disadvantaged, in that they were used to seeing images captured on spectral domain systems and displayed on very high-resolution monitors. Alternatively, they may have had the advantage of having seen older images in the HES, which optometrists may not have done. Therefore, it is unknown whether or not vignettes created from more recent information may have favoured the performance of one professional group over the other. The important point is that the trial design ensured a ‘level playing field’ in terms of the assessments that both groups, and the experts, carried out.

Finally, the final reference standard was not available by the time that participants’ training performance had to be assessed (see Reference standard). This could have been a serious limitation if the information used to assess participants’ performance at the time misclassified participants with respect to their performance and their ability to progress in the trial. However, as previously stated (see Chapter 2, Reference standard), when all experts had classified all vignettes, we checked the performance of all applicants for their training vignettes using the final reference standard classifications. No applicant was refused admission to the main trial on the basis of the interim expert classifications who would have progressed to the main trial on the basis of the final reference classifications.

Health economics

The cost-effectiveness results should be considered in the light of some limitations of the study. Because the ECHoES trial was virtual, participants were asked questions about a service not implemented yet, which posed challenges for optometrists in identifying appropriate costing information for their potential nAMD monitoring review provision. The health economics questionnaire was not a compulsory part of the trial and we wanted to avoid overburdening participants with lots of questions. Therefore, we used expert opinion to inform the economic evaluation about the types and models of different pieces of equipment, the average volume of patients using some of the equipment items and the expected working life of equipment. Furthermore, the costs used in the economic evaluation rely on the assumptions inherent within the decision trees shown in Figures 1 and 2.

Expert opinion was also used to help to map the pathways for the care cost model with respect to the likely courses of action arising from various decisions being made by optometrists and ophthalmologists. In particular, the optometrist pathway assumes that all patients classed as reactivated receive a second monitoring review in hospital (at the more expensive ophthalmologist cost, rather than the cheaper optometrist review cost), which increases costs for correct judgements of lesion reactivation in the optometrist pathway but also enables a second opportunity for any errors to be corrected before costly ranibizumab injections are given. In real-world implementations of shared care, other pathways may be devised or pathways may improve with time after they have been implemented. For example, the optometrist pathway is likely to include direct clinical examination, as well as review of CF and OCT images, and an integrated shared care pathway could allow the HES to review information obtained by community optometrists following rapid referral (as envisaged by the last item of the economic question, see Appendix 3, Q8), rather than repeating monitoring tests. Alternatively, shared care pathways may also improve with time after they have been implemented.

Views of patients and health professionals about the shared care model

A purposeful sampling approach was adopted within and across the research to ensure that the feasibility and acceptability of the proposed shared model of care for nAMD was captured from a range of perspectives. However, ophthalmologists and optometrists were recruited from specialist conferences, which may limit the extent to which their perspectives are representative of optometrists and ophthalmologists in the UK. Furthermore, service users were recruited from Macular Society support meetings and such individuals may be more proactive and informed about their condition than non-members.³⁷ Service users at the support groups who were willing to be contacted were white British, possibly because white people may be more susceptible to developing nAMD⁴³ or because people from ethnic minority groups are less likely to access eye care services.^44,45 It should also be acknowledged that all service users attended the same eye hospital for their nAMD care and some aspects of their care may differ to other hospitals throughout the UK, although the themes relating to current experiences of hospital care have also been highlighted by previous research.^34,36,37

Focus groups were used to explore and understand key issues when considering barriers and facilitators to implementation. Separate rather than mixed focus groups were undertaken to capture any potential interprofessional trust issues which emerged from previous research.³⁵ One-to-one interviews were conducted with other health professionals because it was not possible to ascertain a convenient location, date and time to organise a third focus group. These interviews provided a rich account of the perceived feasibility and acceptability of a shared care scheme and allowed the findings from the focus groups to be followed up further and explored in-depth.

None of the participants had experience of shared care for nAMD. Research has questioned whether or not evaluations of hypothetical scenarios accurately relate to judgements in real-life situations.^46,47 However, participants gave negative as well as positive views of the shared care model, which suggests that they carefully considered the practicalities of implementation. In addition, focus groups provided an opportunity to prompt a range of issues about shared care to be discussed which participants may not have otherwise considered individually in one-to-one interviews.⁴⁸ Furthermore, the issues identified in this study about a hypothetical shared care scheme mirror many of the findings from studies in which participants gave feedback after direct experience of shared care.^35,41

Lessons for a future shared care approach to the management of neovascular age-related macular degeneration

It is clear that, given foreseeable health technologies for treating nAMD (including potential emerging therapies combining anti-VEGF drugs with stereotactic radiotherapy), the need for efficient methods of long-term review will remain an urgent priority. Some form of shared care with community-based optometrists is one approach for achieving this, notwithstanding the findings of the economic evaluation (see Future research). The ECHoES study has demonstrated that community-based optometrists can develop competency in decision-making about lesion reactivation that is equivalent to the competency of ophthalmologists working the HES. Although it was not straightforward to conduct the study in a short period of time, we were able to apply the methods we planned at the time of the grant application with few modifications. We would recommend further trials of this nature to address research questions where appropriate data repositories can be identified.

Lessons for a future economic evaluation alongside a virtual trial

The virtual trial imposed the limitation of asking participating optometrists to identify the resources and likely costs for providing a service that had not yet been implemented. This is not an intrinsic feature of virtual trials but is a likely feature, since the attraction of a virtual trial is greatest when there are obstacles to provide a service. The absence of an existing shared care pathway also contributed to uncertainty about the cost-effectiveness estimates. This was highlighted by the economic evaluation sensitivity analyses, notably the analysis which excluded rereview in the HES of a patient rapidly referred by a community-based optometrist.

Lessons for qualitative research alongside a virtual trial

This study highlights the importance of exploring the views of relevant stakeholders about the acceptability of shared care for nAMD and barriers to its implementation alongside a virtual trial. The qualitative research identified key concerns that would need to be addressed in formulating a concrete shared care model. Had the study proceeded as originally proposed by the applicants, the headline non-inferiority findings might have led to unreasonable optimism about the feasibility of shared care for nAMD.