Not surprisingly, there were many presentations at this year’s Optometry Tomorrow conference that looked at the impact of the Covid-19 pandemic on eye care and how this may influence the nature of future care throughout the UK. There were also several presentations offering an update on OCT assessment and the various ways of assessing anterior eye structures.
Future vision of urgent eye care
Zoe Richmond, clinical lead of optometry at NHS England National Eyecare Recovery and Transformation Programme, looked at how the recent pandemic had influenced the way we provide urgent eye care in England.
Richmond began by outlining a number of studies showing how eye care has changed in the past couple of years. In England, the waiting list for ophthalmology has increased every month from December 2020 to a staggering 1000+ people per 100,000 in March 2022. That said, the numbers waiting for longer than 52 weeks to be seen has dropped. Moorfields Eye Hospital experienced a significant reduction in total attendance numbers for urgent and emergency care, despite the clinicians readying themselves for a surge from other hospitals. Worryingly, this drop is related to patients neglecting symptoms of visual loss. As a result of this, 67% of survey responses reported a reduced number of retinal detachment surgeries.
The conclusion is that there has been a drop in retinal detachment diagnoses and fewer cases recorded for posterior vitreous detachments and retinal tears during Covid-19 related lockdown throughout the UK, compared against an equivalent period in 2019.
Local care schemes, such as CUES, have been a success. In Manchester, under the CUES scheme, 85.7% patients are managed entirely in primary care, while in Kent, the use of IP optometrists in primary care has reduced attendance at Emergency Eye Departments (EED), with 95% of patients fully managed in the community. In Bath, North East Somerset, Swindon and Wiltshire, face-to-face appointments were reduced, with 22% of consultations appropriately managed entirely through a virtual service.
Where CUES has been implemented, ‘the scheme demonstrates a high level of primary care activity alongside a sustained reduction in EED cases. The case-mix of patients seen within EED appears to be of a less benign nature than those cases seen prior to the introduction of CUES.’ A significant conclusion is that ‘the evaluation of a non-referred population seen in primary care CUES supports the view that the service is clinically safe.’ The benefits of primary care include improved patient access, care offered nearer to home, reduced pressure on secondary care resources, and better use of equipment and expertise.
Richmond then introduced the concept of Optometry First, ‘a comprehensive new care model fully utilising primary care optometry in the delivery of first contact care to resolution and continuity of care for people with long term eye conditions, working in partnership with the hospital eye service.’ Already under trial in England, the new scheme picks up on much of value from CUES and is likely to form the basis of future eye care in England.
In conclusion, Richmond stated that ‘my vision of urgent eye care in England is that the whole population of England has access to urgent eye care locally and should think Optometry First, whatever their eye or visual concern.’
OCT Essentials
As we all get more used to OCT assessment, a thorough revision of this area is always welcome and usually identifies a new area of learning. Dr Rebekka Heitmar, optometrist and reader at the University of Huddersfield, gave an excellent, essential knowledge presentation that reminded everyone of the pitfalls of OCT assessment.
Firstly, it is important to remember some of the common factors that can reduce OCT scan quality. These include the following:
- Set-up-related: poor patient alignment is common
- Patient-related: these are multiple and include poor fixation, ocular media transparency, eye movements, ability to sit still
Each instrument manufacturer will provide you with different quality indices, for example Zeiss will give you a quality rating out of ten where a value between six and ten is classed as acceptable and colour coded in green while anything from five and below is classified as poor and colour coded in red. Importantly, when assessing longitudinal data (for example, across several visits) it is advisable to compare scans of similar quality as you may otherwise introduce errors.
Heitmar went on: ‘You should always aim to get the best quality possible. This means that when, for example, the first scan you obtain is only six out of ten you should try to get a better quality and, where this is not possible, try to determine why you are unable to improve the scan. This might be due to factors such as cataracts, corneal abnormalities, or an unstable tear film and so on.’
Even when scan quality is insufficient for longitudinal analysis, ‘you may still be able to use the scan for qualitative analysis, such as identifying lesions, abnormalities, bleeds, thinning and others.’
The speaker then explained the perils of normative databases. ‘All commercially available OCT devices have in-built normative databases, which are used to provide the clinician with colour-coded outputs of their patient data. According to FDA guidance, normative databases are used for clinical purposes and should comprise at least 300 individual datasets. However, there is not much guidance in respect to refractive status and other systemic confounding factors which may well play a role for OCT output,’ she said. Also, OCT devices vary between manufacturers, with respect to ethnicity, age and other clinical information.
While normative databases are a standard for visual fields data, they are not when it comes to OCT scan analysis. ‘As a rule of thumb, scan your patients early on to have a baseline reference for their follow-up.’ This is important because refractive error and other factors have an impact on outcome variables calculated. Heitmar summarised: 'Your patient’s baseline is your best reference for between-visit comparisons.’
In a separate presentation on anterior OCT assessment, Adam Wannell, head of clinical programme development at Newmedica, noted how a number of anterior eye structural parameters, such as anterior chamber angle, depth, width and volume, have been associated with angle closure when lower in value, ‘but in most cases it is unclear what is clinically significant.’ For this reason, Wannell confirmed: ‘Gonioscopy remains the gold-standard test to evaluate the iridocorneal angle and AS-OCT imaging is an important supplementary test to complement gonioscopy.’
Corneal Dystrophies
In a most comprehensive lecture looking at corneal dystrophies, Aston University lecturer in optometry, Dr Raquel Gil-Cazorla, took a close look at the wide range of inherited corneal dystrophies, from the common epithelial basement membrane dystrophy to less well-known conditions, such as Schnyder corneal dystrophy (figure 1) - a disease of childhood that should always warrant a systemic cholesterol check if suspected.
Unlike corneal degenerations, which are non-familial, unilateral or asymmetric and characterised by deposits and vascularisation, dystrophies tend to show the following characteristics:
- Bilateral; high grade of symmetry
- Early onset; typically present in the first or second decade of life
- Hereditary; autosomal dominance is most common
- Classification based on clinical appearance is insufficient
- Genetic knowledge is mandatory; ask about the family
- No inflammatory process associated
- Slow progression
- High and variable percentage of recurrence after treatment
This then led to a healthy debate about why keratoconus is so difficult to classify precisely, and also how genetic testing is likely to prove to be a game changer in the coming years in this area.
Slit-Lamp Skills
Helen Wilson, lead optometrist at Manchester Royal Eye Hospital, is always worth a listen. In an excellent review of anterior segment assessment, she reviewed the use of both van Herrick and Redmond-Smith techniques, and offered hints on what to do with the results. Like me, she prefers a decimal or percentage grading to the non-linear van Herrick approach (figure 2). Wilson also emphasised how accurate assessment is unlikely if the optic section is too far onto the cornea, or if the peripheral cornea is too opaque, as with prominent arcus.