Gonioscopy forms an essential part of the glaucoma evaluation, enabling the structure of the iridocorneal angle to be seen, which is important in diagnosing and monitoring eye conditions associated with glaucoma. However, Schlemm’s canal (SC) can be poorly visible in the angle, especially in excessively pigmented eyes.

Blood reflux from episcleral veins to the SC is a well-known sign that helps one to visualise the SC

 and can be caused by the pressure of the goniolens on the episcleral veins, reduced intraocular pressure (IOP) or both.

 Three quarters of outflow resistance of the aqueous humour in normal eyes comes from the trabecular meshwork (TM), while 25% of the resistance comes from SC.

 The juxtacanalicular meshwork is responsible for normal outflow resistance in the TM.

Many glaucoma surgeries aim to overcome this resistance of outflow, which may reduce the IOP. The trabecular micro-bypass implant iStent inject (Glaukos Corporation), which received CE Mark clearance in Europe in 2010 for the treatment of open-angle glaucoma,

 aims to connect the anterior chamber directly with SC, thus overcoming the resistance of the TM.

In one study, blood reflux was seen in nearly all (91%) of eyes immediately after implanting iStent,

 but there are few case reports about the late hyphaema that can occur through the implant following surgery.

 We evaluated blood reflux during gonioscopy 3 to 6 months following implantation of either the trabecular micro-bypass devices iStent inject or the newer-generation device, iStent Inject W, to evaluate the effectiveness of the implantation and adjust the drugs therapies patients were on if necessary.

In a case series, 22 eyes from 20 patients who had been diagnosed with either early primary open-angle glaucoma (POAG) or ocular hypertension (OHT), and who also had cataracts and prior difficulties with eyedrops, received implants of either iStent inject or iStent inject W combined with their cataract surgeries. All procedures were carried out by the same surgeon at the department of ophthalmology in Staedisches Klinikum Dresden hospital in Dresden, Germany.

Two stents were implanted in each eye nasally. 14 eyes received iStent inject and eight eyes were implanted with iStent inject W. Patients were treated with at least one hypotensive eye drop before the surgery.

The patients were controlled regularly after the surgery and the IOP was measured at each visit. The required drugs therapy was reduced in most cases and adjusted to reach the target pressure according to the guidelines of European Glaucoma Society, with consideration of the IOP before the surgery.

There were no significant complications intraoperatively or after the surgery. Gonioscopies with Goldmann 3 mirror classic contact lens 903 was performed on the eyes 3-6 months after surgery to evaluate the blood reflux through the devices.

The gonioscopy lasted about 1 minute with light pressure applied to the lens and slightly greater pressure applied nasally, before the pressure was eased off and evidence sought of possible blood reflux from the lumina of either of the stents.

Following the surgeries, patients had a mean IOP of 18 mmHg and a mean of 1.25 glaucoma eye drops was used. The patients did not require any further interventions and there were no complications observed intraoperatively or postoperatively.

Three of the patients who had an IOP of less than 15 mmHg had blood reflux through one of the two iStents during gonioscopy, but this was not visible in the other 19 eyes.

An 82-year-old woman with POAG had an IOP of 13 mm Hg. She was prescribed brinzolamide (Azopt, Alcon Laboratories) eyedrops with a dosing schedule of twice a day.

Gonioscopy was performed 3 months following the surgery. The iStent inject w was implanted. The results can be seen in Figure 1.

An 85-year-old male with POAG had an IOP of 12 mmHg. He was provided with derzolamide plus timolol eyedrops (Cosopt, Merck & Co) for twice-daily use.

A gonioscopy was performed 5.5 months after the surgery. iStent inject was implanted (see Figure 2).

A 72-year-old male with POAG had an IOP of 15 mmHg. He was prescribed tafluprost (Taflotan, Santen Pharmaceutical) eyedrops to be taken once a day.

Gonioscopy was performed 3.5 months following his surgery. iStent inject W was implanted. Results can be seen in Figure 3.

From the findings of these three cases, we can see that all the patients who had late blood reflux had an IOP under 15 mmHg, whereas other patients with higher IOPs did not. It is well known that the IOP following iStent implantation should not be lower than the pressure in the episcleral veins, which is usually 6-9 mmHg, but it can be elevated in glaucoma patients.

Moreover, it is widely accepted that blood reflux in SC is more likely to occur in eyes with low IOP2 since lowering the IOP reportedly facilitates blood movement into SC.

The blood reflux has been classified into three patterns:

No filling, suggesting the collapse of SC and atrophy of collector channels;

Patchy filling of SC suggesting the partial collapse of SC; and

Full filling of SC with blood indicating patent SC and healthy collector channels.

It is important to note that the diameter of SC is between 50.8 μm and 393.5 μm,

 and this diameter is smaller in older patients in comparison with children. Moreover, the diameter of SC is smaller in glaucoma patients compared with those who do not have glaucoma.

We know that the central outlet in iStent inject and iStent inject W is 80 μm and that the side flow outlet is 50 μm. This may lead to the ineffective implantation of the device in some cases, such as where the diameter of SC is small, which may obstruct the outflow.

This could be the explanation for observing blood reflux just from one stent in our three patients and not in both stents, but it could also be related to the IOP and the amount of blood in SC. These considerations may also explain the minimal blood reflux seen in the third patient, which does not obscure the vision of the angle.

On the other hand, the excessive treatment of IOP in glaucoma patients following implantation of the stent may lead to a spontaneous recurrent microhyphaema in the anterior chamber. In these patients, reducing the therapy would be more reasonable and IOP phasing may offer a better view to optimise it. 

In conclusion, gonioscopy may offer a cost-effective method of evaluating the function of iStent after implanting it and could help in adjusting the therapy after the surgery.

---
Abdelwahhab Azzawi, MD, FEBO, MRCPS (Glasg)


E: Abdelwahhab.Azzawi@klinikum-dresden.de


Dr Azzawi is an ophthalmic consultant based at Department of Ophthalmology, 

Staedtisches Klinikum Dresden, Dresden, Germany

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Kanski’s Clinical Ophthalmology: A systemic approach. Eighth edition. 2016 Elsevier.

Bill A, Svedbergh B. Scanning electron microscopic studies of the trabecular meshwork and the canal of Schlemm – an attempt to localize the main resistance to outflow of aqueous humor in man. Acta Ophthalmol (Copenh). 1972;50:295-320.

Pillunat LE, Erb C, Junemann AG, Kimmich, F. Micro-invasive glaucoma surgery (MIGS): A review of surgical procedures using stents. Clin Ophthalmol. 2017;11:1583-1600.

Popovic M, Campos-Moller X, Saheb H, et al. Efficacy and adverse event profile of the iStent and iStent inject trabecular micro-bypass for open-angle glaucoma: A meta-analysis. J Curr Glaucoma Pract. 2018;12:67-84.

Fernandes Resende A, Patel NS, Waisbourd M, Katz LJ. iStent trabecular microbypass stent: An update. J Ophthalmol. 2016;2731856.

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Grieshaber MC, Pienaar A, Olivier J, Stegmann R. Clinical evaluation of the aqueous outflow system in primary open-angle glaucoma for canaloplasty. Investigative Ophthalmology & Visual Science. 2010;Vol.51:1498-1504. doi:https://doi.org/10.1167/iovs.09-4327.

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Articles

Gonioscopy may offer a reasonable and cost-effective method to evaluate the function of the trabecular micro-bypass device post-implantation and it could help in adjusting the therapy after the surgery.

Monitoring blood reflux during gonioscopy in glaucoma 

The World Health Organisation (WHO) announced a new flagship initiative, “a mental health coalition to support system reforms and COVID-19 recovery” in Europe.

This was undertaken because of the organisation’s recognition that “mental health is a key public health concern in the WHO European Region – more than 110 million people are living with some kind of mental health condition, accounting for over 10% of the population.”

“The mental health flagship will bring together a broad coalition of mental health leaders, champions, service users and other partners to improve mental health policies and practices across the region,” the WHO said in a statement.

Considering the COVID-19 virus, focusing on mental health now is especially important given that the measures to prevent the virus from spreading, such as social distancing and quarantining, in addition to the dangerous working conditions for health care workers, are having a psychological impact on the population and exacerbate pre-existing anxiety.

The WHO explained that the Mental Health Initiative will challenge “stigma and discrimination by improving mental health awareness and literacy among not only the public but also service providers and decision makers.”

In addition, it will enhance access to “person-centered, rights-based mental health care in communities. This will expedite progress towards universal health coverage for people with mental health conditions and make the case for a parity of esteem between mental and physical health.”

The Mental Health initiative is one of 4 launched by the WHO. The other 3 priorities for WHO/Europe over the next 5 years are digital health and innovation, behavioural and cultural insights, and immunization.

Organisation is kicking off a flagship initiative as it views mental health as a key public health concern in the WHO European region, where more than 110 million people are living with some type of mental health issue. 

WHO initiative builds a coalition for system reforms, COVID-19 recovery in Europe

The coronavirus pandemic has triggered a seismic shift in the way ophthalmologists interact with their patients, forcing them to think on their feet and find ways to quickly adapt their workflows. 

However, as the crisis continues, it is becoming apparent that some of the changes they have had to make, such as increasingly opting for virtual consultations, could become more permanent, as evidence of their benefits to doctors and patients alike starts to mount. 

Arguably, the pandemic has paved the way for greater opportunities for positive change within ophthalmology and indeed, in healthcare in general.

I asked Prof. Mariya Moosajee, consultant ophthalmic surgeon and clinical academic ophthalmologist at Moorfields Eye Hospital, London, how her working life has changed and how those who specialise in providing services for genetic eye disorders can continue to provide the best care for their patients both during the pandemic and beyond.

Prof. Moosajee’s speciality is genetic eye disease, so the majority of her patients have been deemed non-urgent during the pandemic. 

A lot of such patients across the UK have seen their appointments cancelled, but Prof. Moosajee decided to consult all her patients virtually from the start of the crisis.

How have you had to adapt your workplace during the pandemic?

I have been able to work from home and consulted patients either by telephone or using ‘NHS attend anywhere,’ a secure web-based platform for patients with pre-arranged video consultation appointments, that was nationally funded by National Health Service (NHS) England and NHS Improvement to support NHS trusts and foundation trusts in their response to the COVID-19 outbreak.

I hold my clinics at the same time as they would have been held pre-COVID-19 and allocate patients to my team. I then meet with my colleagues at the end of every clinic on Microsoft Teams so that they can present each case.

We discuss the patients’ future management as a multidisciplinary team; we have a family support officer; a developmental paediatrician; a genetic counsellor; an extended role orthoptist; a low vision optometrist and a paediatric ophthalmology fellow. If we feel our patients need a low vision assessment or specific paediatric input (as a vast number of genetic eye disease patients have systemic features), then the relevant personnel will follow up the patient with a further phone call. It has worked really well; we have consulted 220 patients in total: 150 children and 70 adults with genetic eye disease.

We are restarting face-to-face clinics in the next month. At that stage we will have prioritised patients that will need to come in for clinical assessment and to give blood samples for genetic testing.

Adults who have had recent ophthalmology assessments locally or in other services at Moorfields can be sent blood packs which enables them to take their own blood without having to travel into London and send the sample back to us so we can process it for genetic testing. In fact, the whole process can be undertaken remotely.

What are your views on virtual consultations?

I have been pushing for virtual consultations in genetics for a long time. Prior to COVID-19 (last April–June 2019), we undertook a patient-reported survey with just over 100 paediatric or adult participants, who were either new or follow-up patients, to ascertain their views on virtual consultations and their acceptability.

We found that over 65% percent of participants prefer to have their investigations carried out locally, followed by a virtual consultation with specialists at Moorfields Eye Hospital for the review of these results. Adult participants favour video calls, with contact via the telephone being the least popular response.

The opposite is true for parents and guardians of children, who prefer contact via telephone over video call. There was no difference between the views of new or follow-up patients. Interestingly, despite most patients preferring virtual contact, the majority do not want to be seen virtually for every appointment until a treatment or trial becomes available.

What innovations do you think might be needed in the future?

I do not think we can go back to the way we were working. We can greatly increase our efficiency and patient experience by a combination of virtual and face-to-face consultations.

Patients do not want to wait for hours to have imaging and see a consultant, but they definitely want to see specialists who know about their rare genetic eye condition and who can assess the results of investigations undertaken locally, as well as inform them of the latest research and trials.

The long, detailed records we take in genetics on the onset and progression of symptoms, and prenatal, birth and family history can all be undertaken virtually. Genetic counselling is also a lengthy process that involves an unrushed conversation to ensure patient understanding of the complex topic of inheritance and genetic mutations, informed consent and family planning.

Studies in cardiac and oncogenetics in the Netherlands showed high levels of patient satisfaction for those receiving virtual genetic counselling. I would strongly recommend Telegenetics moving forwards.

In the UK, genomic medicine services are being introduced across all medical specialities, funding for genetic testing is becoming centralised and whole genome sequencing will soon be available to most patients on the NHS. We are trying to encourage more ophthalmologists around the country to order genetic tests for patients.

Moorfields Eye Hospital is also hoping to provide a virtual genomic service to ophthalmologists, to offer guidance and advice on how to manage genetic eye disease patients locally without the need to send them to tertiary referral centres unless necessary. I think this will be a huge step forward for patients who have previously not been able to access genetic services due to local funding restrictions.

I have also created an open access web-resource called Gene.Vision, which is an A-Z of genetic eye disease with two interfaces; one for healthcare professionals and the other for patients. The version for patients includes in-depth sections on how to cope with sight loss and associated aspects of daily life that can be affected, such as driving, education and employment.

The aim of the resource is to feature the signs; symptoms; genetic causes; patient management; referral needs; current information on research and trials for a disease/gene; and any support groups that would be beneficial for the patient, for each genetic eye disease. It has been tested by patients with sight loss with input from digital accessibility consultants, one of who is deaf-blind with Usher syndrome. It will be launched next month (www.gene.vision).

How can you best serve your patients during the pandemic?

Most genetic eye disease patients had their appointments cancelled during the lockdown. When you are forced into isolation, it can cause some individuals to focus more strongly on their own health and well-being.

Calls to sight loss charity helplines increased but they had no expertise to answer the medical queries. So, I offered to undertake a voluntary weekly ‘Ask the expert session’ for Retina UK, Microphthalmia, Anophthalmia and Coloboma Support (MACS) charity and Aniridia Network.

I spoke to at least six patients per session and every caller had a valid reason to get in touch; issues raised included not getting access to expert services, deterioration in vision and interestingly, I received a number of calls from patients who were experiencing increased visual hallucinations as part of Charles Bonnet syndrome (CBS). Based on this anecdotal evidence, we undertook a survey of 45 elderly patients with sight loss due to CBS, with over 40% of them having macular-related disease.

Over 55% of patients reported increased frequency of visual hallucinations;

Approximately 50% had alterations in the nature of their hallucinations and emotional response in terms of more sinister hallucinations, with more associated fear and anxiety; and

Nearly 70% felt greater feelings of loneliness but 60% had not accessed support services.

It is clear from this that we must learn to stay connected with our patients, ensuring they do not feel isolated. Sending a letter of cancellation or discharge is not appropriate during these difficult times. A phone call by an eye clinic liaison officer or genetic counsellor can be very gratefully received by patients. Sight loss charities may be able help in this regard but, like many, they have been suffering from reduced income and furloughed staff. 

Prof. Mariya Moosajee, MBBS, BSc, PhD, FRCOphth

E:  m.moosajee@ucl.ac.uk
Professor Moosajee has no financial disclosures.

COVID-19: How one ophthalmologist is dealing with non-urgent cases 

Cedric Schweitzer, MD, is an ophthalmologist based at the University Hospital Bordeaux in France.

The femtosecond laser is widely used in ocular surgery, particularly in refractive surgery with LASIK flap creation or small incision lenticule extraction, as well as in corneal graft or corneal inlays for keratoconus. Owing to the very short pulse of the laser, the technology provides highly precise ocular tissue cuttings without causing collateral damage to surrounding structures.

The application of femtosecond laser to cataract surgery was the obvious next step of the technology and has led to femtosecond laser-assisted cataract surgery (FLACS) emerging as a recent breakthrough. However, it has required additional developments such as specific docking systems and real-time imaging to enable cuttings of the opacified crystalline lens to be made without distortion of ocular structures during the laser procedure. Safety zones to preserve surrounding structures within the eye also needed to be considered (Figure 1).

As expected, laser-created capsulotomy is more precise, circular and centred than manual capsulotomy. In addition, corneal incisions have more reproducible squared-edge architecture and greater resistance to leakage than manual incisions using a calibrated knife. Furthermore, the fragmentation of the lens provided by the specific pattern of femtosecond laser impacts within the lens significantly reduces the amount of ultrasound used to remove the remaining pieces of the lens during the phacoemulsification phase.

However, despite the femtosecond laser’s high level of technical capabilities in cataract surgery, the clinical benefit for patients remained unclear and a Cochrane meta-analysis could not determine the equivalence or the superiority of FLACS to phacoemulsification due to a very low certainty of the available evidence and the unclear risk of bias in included studies.

With cataract surgery being one of the most routinely performed operations in medicine, it became clear that such a comparison was necessary, not just for patients but for healthcare professionals and decision-makers as well, to enable them to provide recommendations and potentially facilitate the spread of the technology.

The FEMCAT trial was a large-scale, independent, randomised clinical study which took place at five centres in France. It was designed to compare anatomical, visual and refractive outcomes between FLACS and conventional phacoemulsification cataract surgery among 907 patients (1,476 eyes) who received either bilateral or a unilateral cataract surgery by one of these two methods. We included a wide range of cataract severity grades that were likely to be representative of the French population who undergo cataract surgery every year in France.

The success rate was defined by four relevant outcomes in cataract surgery: the absence of perioperative complications up to the 3-month visit; a best corrected visual acuity of 0.0 LogMAR or better; an absolute manifest refractive error below 0.75 dioptres; and the absence of significant change in corneal astigmatism between the preoperative visit at month 3 post-operatively.

The femtosecond laser was found not to be superior to phacoemulsification in cataract surgery and thus FLACS failed to provide an additional clinical benefit for patients despite its advanced technical performance. Indeed, we observed a high rate of uncomplicated surgery of 94.2% up to the 3-month visit without significant difference between the two groups. These results were recently reported in 

The rate of absolute manifest refractive error below 0.75 dioptres or 0.5 dioptres were up to 81.4% and 76.5%, respectively, again without significant difference between the two groups (Figure 2). Interestingly, we did not observe any difference in visual, refractive or anatomical outcome measures between the two groups whatever the cataract type or the cataract severity grade.

In order to provide robust data on a large sample size, the FEMCAT trial was designed to minimise the risk of bias. We strived to provide masking procedures until the last follow-up visit wherever we could, including having a sham laser procedure for patients randomly allocated to the phacoemulsification group. Additionally, an independent adjudication committee composed of three independent ophthalmologists masked to the trial allocation was designated to evaluate all adverse events for increasing objectivity in safety evaluation.

We also standardised all the associated procedures (IOL optical and biomaterial characteristics or phacoemulsification machines) in each centre to limit the risk of bias and to analyse only the safety and efficacy profile of the studied surgical procedures. Finally, four surgeons experienced in cataract surgery were involved in the trial at each centre. They were also likely to be representative of cataract surgeons in France.

FEMCAT was also a cost-effectiveness trial and so we collected all direct expenses related to the surgery using a real-life micro-costing approach based on detailed resources used during the surgery. It included the prices of items such as knives, viscoelastic products, syringes or cannulas; the expense of the laser and disposable docking systems; and all costs related to phacoemulsification machines.

We also estimated all inpatient and outpatient costs, including those related to the follow-up or rehabilitation care arising until the treatment success measurement was obtained using the French

national health data system, a claim database encompassing 98

.8% of the French population. With comparable clinical outcomes between the two groups, the cost of FLACS was significantly higher and thus the laser was found not to be a cost-effective procedure for cataract surgery.

Indeed, all inpatient and outpatient costs as well as all direct costs of surgical items or phacoemulsification machines were not significantly reduced in the FLACS group. Thus the financial loss incurred by laser was not compensated, even in part, by either better clinical efficacy or a significant reduction in other direct costs during the surgical procedure or thereafter.

It is likely that the technology’s expansion will need to be facilitated by a significant reduction in femtosecond laser procedure costs in the future, including those incurred indirectly, for example by phacoemulsification machines that are used to aspire the fragmented lens.

The femtosecond laser was confirmed to be reliable and precise regardless of the cataract severity grade or the clinical experience of surgeons in our trial. Also noteworthy was that the laser enabled reliable images of the anterior structure of the eye to be obtained irrespective of the cataract severity grade, even for very mature cataracts, and allowed for reproducible cuttings of ocular tissues in the FLACS group.

Moreover, we did not observe any significant adverse event during the femtosecond laser phase. We reported only six cases of incomplete capsulotomy without subsequent anterior capsule tear.

Ultrasound time and energy were also significantly reduced in the FLACS group. Finally, we can also confirm the learning curve of FLACS was short without significant adverse events seen in the first cases by each surgeon.

While FLACS does not provide an additional clinical benefit for patients over phacoemulsification cataract surgery today and was not found to be a cost-effective strategy in our trial, it is fair to acknowledge that this technology is still in its infancy and some perspective exists. Indeed, FLACS has provided new insights into anterior segment surgery, particularly in paediatric cataracts, by enabling posterior laser capsulotomy, which, when it is performed following crystalline lens extraction, could limit the risk of amblyopia related to the posterior capsule opacification.

Additionally, owing to the real-time imaging technology and the three-dimensional zones of laser treatment or safety zones the surgeon can define prior to the laser procedure, this technology can also improve the surgical outcomes of some severe anterior segment diseases such as severe capsulophimosis. The development of new IOLs that would be a better fit to the very precise and circular capsulotomy provided by the femtosecond laser machine could also help improve IOL stability or centration along the visual axis.

Furthermore, innovations such as new aspiration machines associated with the femtosecond laser could help limit the need to use the phacoemulsification machine and reduce the overall cost of the surgical procedure. Finally, FLACS may also pave the way to a new era of automation and robotics in cataract surgery.

In conclusion, we believe that the FEMCAT trial provides useful information that healthcare providers and decision-makers should consider before implementing this new technology in routine practice for cataract surgery. Although FLACS represents an innovation that could open new doors in ophthalmology, it is necessary to rationalise the overall costs of cataract surgery as well as consider the individual patient’s journey when considering whether or not it is appropriate to choose FLACS over phacoemulsification.

Figure 1. Real-time imaging system showing an automated recognition of anterior and posterior faces of the cornea, and anterior and posterior faces of the lens. The green zone is the laser treatment zone within the lens and the red zone is the safety zone based on the pupillary margin and the posterior capsule of the lens. 

(Image courtesy of Dr Cédric Schweitzer)

Figure 2. FEMCAT trial: Safety and efficacy analyses at 3 months in modified intent-to-treat populations.

Dr Schweitzer is an ophthalmologist at Bordeaux University Hospital in France and is the principal investigator of the FEMCAT trial, which was fully supported by a grant for the French ministry of social affairs and health. The French ministry of social affairs and health did not participate in the collection, management, statistical analysis and interpretation of the data or in submitted manuscripts. Dr Schweitzer has no financial disclosures.

With its higher costs, FLACS failed to provide an additional benefit over phacoemulsification for patients or in healthcare settings, despite its advanced capabilities.

Femtosecond lasers and phacoemulsification go head to head in French trial

Much has been published about the risks of contracting Covid-19 from tears and the precautions that need to be taken. This article will evaluate the risks surrounding the most commonly performed procedures during an ophthalmic exam, focusing particularly on procedures requiring contact with the eye, such as tonometry.

Given that the COVID-19 pandemic involves a new virus, which has spread and behaved unpredictably, our understanding of patient management in this new reality has evolved. Consider that in March, a study published in the journal 

 concluded that it was unlikely that COVID-19 patients shed virus through their tears.

However, less than two months later, a new study from Johns Hopkins University, Baltimore, United States, concluded differently: “These results indicate that ocular surface cells including conjunctiva are susceptible to infection by SARS-CoV-2, and could therefore serve as a portal of entry as well as a reservoir for person-to-person transmission of this virus.”

 They added that the results showed that the ocular surface could be an even more significant reservoir for virus particles than suggested by other recent clinical studies.

Given these recent findings, we must be vigilant about reducing the risk of virus transmission for our staff, as well as our patients. In our clinic, we have implemented specific safety measures that should reduce the risk of infections in general.

These include: providing face masks to each patient when entering the clinic; measuring body temperature by a non-contact method; excluding patients with any potential COVID-19 symptoms; frequent ventilation of all rooms; adding barriers around instruments and the reception area; and disinfection of all surfaces every hour. We have also made it mandatory for the entire clinic team to wear gloves, safety glasses and facemasks.

According to a World Health Organisation-funded study, face masks and eye protection/safety glasses provide the best protection in reducing the risk of infection. Writing in the 

 the researchers looked at 216 studies with more than 25,000 COVID-19 patients and found that face masks resulted in the largest reduction of risk (95% CI: 0.07–0.34), followed by eye protection (95% CI: 0.12–0.39).

In addition, most eyecare practitioners very quickly adopted the placement of a plastic barrier around their slit lamps in order to reduce transmission risk. But what about other routine eye exams – what are the risks and how can we minimise them?

Among the first recommendations made by the American Academy of Ophthalmology and other ophthalmic societies was to place a plastic shield around the exterior of slit lamps.

A recent study published in a letter to the editor in the British journal 

 tested two sizes of plastic shields using a breathing simulator to replicate a normal adult breathing pattern.

Researchers measured spray without the plastic barrier, with an 11x11x0.2-cm barrier and a larger 45x44x0.2-cm barrier.

They then measured the number of particles over a 1-minute period. The slit lamp arm was offset at 60° and the test was repeated five times for each shield. A linear regression analysis determined the effectiveness of no barrier and the two barriers, as well as the particle count.

Without any shield in place, the mean log particle count was 3.59 (95% CI: 3.48–3.70). With the standard shield in place, there was a reduction to 3.01 (95% CI: 2.90–3.13; 

<0.01) and a further drop was seen with the larger barrier in place, which lead to a mean count of 2.62 particles (95% CI: 2.50–2.73; 

However, while the larger barrier provided the greatest reduction in particle transmission, the authors pointed out that the larger shield can lead to contact transmission of the virus due to the need to manipulate the slit lamp arm or during tonometry. As a result, the authors noted that the barrier should be used in combination with hand hygiene and surface cleaning.

A highly useful article published in the June issue of the journal 

 outlines the risks and best practices for various ophthalmic tests, including the use of imaging devices, such as those used for optical coherence tomography. The obvious contact points on these devices are the chin rest and head guard where the patient has direct contact, but if the patient is unmasked, droplets from breathing and speaking can also contaminate the surface of the device.

While cleaning and disinfection after each patient is the obvious solution, most imaging device manufacturers have specific recommendations about how this is done without damaging these devices. All manufacturers have developed guidelines for this purpose.

This test places both the patient and the technician at risk due to its lengthy nature and the need for the technician to be in proximity to the patient while the patient is performing the visual field test. The corrective lens and bowl of the perimeter can be exposed to respiratory droplets, while the response button, occluder, head strap and chin rest are in direct contact with the patient. The authors suggest replacing the occluder with a disposable amblyopia patch or gauze, as well as following manufacturers’ cleaning and disinfecting instructions.

This procedure has attracted a certain amount of debate given that the two forms of tonometry—contact and non-contact— have the potential to result in infection transmission.With contact tonometry, the risk is clear from the name – the tonometer encounters the cornea.

Published studies have shown that applanation tonometry can potentially transmit a number of infectious diseases, including adenovirus B and herpes simplex virus 1, while reusable tonometer prisms are able to transmit hepatitis B & C, as well as HIV and Creutzfeldt-Jakob disease.

 The AAO notes that there is no optimal way to disinfect Goldmann tonometers without potentially damaging the device and recommends the use of disposable tonometer prisms, if available, to reduce the risk of viral transmission.

published online in April, ophthalmologists from the University of Hong Kong noted that they had suspended all tests that might result in micro-aerosol, including non-contact tonometry (NCT).

. note in their article that there is no set evidence that there is aerosol transmission with current devices and also point out that NCT enables clinic staff to put more distance between themselves and patients.

However, surfaces around the testing area should be disinfected between patients. The Centres for Disease Control and Prevention also recommends caution in performing tests that result in “aerosolisation of viral particles.”

Interestingly, a 1991 study of NCTs attempted to show the alleged danger of the air puff approach using fluorescence photography to capture droplet splatter when drops were instilled into eyes as the puff of air was applied. However, they could not replicate it with just the patients’ tears.

Can safety rules make vision exams 100% safe?

Based on our review of literature and recommendations that have been published in recent months, it is clear that both societies and ophthalmic equipment manufacturers are providing as much guidance as possible to help clinicians navigate these unchartered waters. It is also certain that, based on our current knowledge of the role of the tear film in COVID-19 patients, with proper safety, cleaning and disinfecting procedures, the risk of viral transmission will remain low.

Of course, virus transmission can never be completely excluded by the discussed transmission pathways. The remaining risk under these circumstances must be estimated.

Wearing masks and safety glasses is a good barrier against direct droplet transmission even within the proximity between patient and examiner in the case of Goldman applanation tonometry or rebound tonometry. Gloves protect the examiner while he touches the patient’s face and eyes. But care must be taken to avoid cross-contamination of surfaces or other instruments, even when wearing gloves.

In addition to clinic staff wearing masks, it is critical that patients are also masked in order to prevent aerosol contamination from breathing or speaking,

 given that aerosols induced by breathing or sneezing have a much higher virus concentration and are much more likely to be infectious. Recent experiments in clinics have shown that glasses worn by the patient steam up by their breath even when a mask is being worn. This illustrates that aerosol production is difficult to avoid in clinical practice.

These examples demonstrate that potential risks caused by the proximity between patient and examiner in case of applanation and rebound tonometry can be reduced in theory, however, in clinical practice potential risks remain. Again, distancing between patients and examiners and frequent ventilation should be the main ways of minimising these risks, as well as the use of NCT.

The Johns Hopkins study sends a strong message to the ophthalmic community – that ACE2 (the receptor for SARS-CoV-2) and TMPRSS2 (a cell surface-associated protease that facilitates viral entry) are present in conjunctival and corneal epithelial cells. This means that the ocular surface can be a potential site of infection or serve an entry port for the virus to enter the blood stream. In addition, they conclude that ocular virus shedding does have the potential to infect others.

Clearly, in order to provide eye care for our patients, resuming practice is the right thing to do. However, until we have a vaccine and see a reduction of COVID-19 cases down to zero, we must adjust and take every precaution possibly to protect our staff, as well as our patients. The use of tests such as NCT, as well as placement of plastic barriers, provide distance between the clinic team and patients, reducing the risk of aerosol viral transmission.

We have implemented specific safety items in our clinic that should reduce the risk of infections in general. By adhering to these specific safety measures as well as implementing some other rules, we consider NCT measurements to be safe with a very low remaining risk.

The greatest threat to professional healthcare providers arises from the close doctor-patient proximity, which is reduced in the case of NCT measurements. Complete avoidance of tonometry in the clinic could cause much more harm than the very low remaining risk for an infection if all safety rules are considered.

r Kermani is medical director, Augenklinik Neumarkt, Cologne, Germany. He has no financial disclosures.

Seah IYJ, Anderson DE, Kang AEZ, et al. Assessing viral shedding and infectivity of tears in coronavirus disease 2019 (COVID-19) patients. Ophthalmology. 24 Mar 2020. Doi: 

Zhou L, Xu Z, Castiglione GM, et al. ACE2 and TMPRSS2 are expressed on the human ocular surface, suggesting susceptibility to SARS-CoV-2 infection. The Ocular Surface. 13 Jun 2020. Doi: 

Chu DK, Akl EA, Duda S, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of sars-cov-2 and COVID-19: a systematic review and meta-analysis. Lancet. 1 Jun 2020. Doi: 10.1016/S0140-6736(20)31142-9.

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Asadi S, Wexler AS, Cappa CD, et al. Aerosol emission and superemission during human speech increase with voice loudness. Sci Rep. 2019;9:2348.

Until we have a vaccine and see a reduction of COVID-19 cases down to zero, we must adjust and take every precaution possibly to protect our staff, as well as our patients.

Minimising risks during routine ophthalmic examinations in the COVID-19 era

This article was reviewed by Prof. Martin S. Zinkernagel

Anti-vascular endothelial growth factor (VEGF) treatment regimens for neovascular age-related macular degeneration (nAMD) generally aim to dry the neovascular lesion, but evidence suggests that not all retinal fluid is the same. When fluid is present, intraretinal fluid (IRF) is associated with poorer vision.

However, some fluid, particularly subretinal fluid (SRF), may be tolerated.

Admittedly, questions about the impact of refractory SRF on visual outcomes, such as threshold values and duration, continue to be raised. Practitioners nonetheless agree that persistent (i.e., residual) IRF is bad for vision and requires aggressive treatment to maintain sight. At multiple international congress debates in recent months, advocates for and against the need for complete fluid resolution when treating nAMD have presented cogent arguments, shared below.

Based on current clinical data and clinical practicability, outcomes are best if all fluid is treated rigorously when using protocols other than a fixed dosing regimen, argued Prof. Martin Zinkernagel of the University of Bern, Switzerland, at the 19th European Society of Retina Specialists (EURETINA) Congress in 2019 in Paris, France. He pointed to multiple studies which show that improvement of vision correlates with a dry macula and that IRF correlates with poorer final vision.

A zero-tolerance approach to the presence of fluid in nAMD is encouraged, since patients who avoid fluctuations in fluid in the macula may have better visual outcomes. Higher central subfield thickness (CST) variability was associated with lower best-corrected visual acuity (BCVA) gains up until 96 weeks, according to pooled treatment and study data from an analysis of the Phase 3 HAWK and HARRIER nAMD registration studies.

 Although the amplitude of the BCVA gain is individual, more stable CST was associated with both better visual outcomes and a fluid-free retina.

Dr David Brown, Retina Consultants of Houston, United States, who spoke at the American Academy of Ophthalmology (AAO) 2019 Retina Subspecialty Day in October 2019 in San Francisco, US, also cautioned that visual outcomes in nAMD are poorer when fluid is tolerated. In the FLUID study of ranibizumab treat-and-extend for nAMD, up to 40% of patients had refractory IRF and the mean improvement in BCVA overall was no more than 3 letters at 24 months.

 Substantially better visual outcomes have been reported in other proactive anti-VEGF treat-and-extend studies.

Practitioner experience confirms that nAMD patients can tolerate a small amount of SRF with no detrimental effects on visual outcome and it may be helpful in some patients, observed Dr Ramin Tadayoni, Hopitaux de Paris, France, speaking at the 19th EURETINA Congress. Both baseline and persistent intraretinal cystoid fluid have a negative impact on visual acuity despite treatment, while SRF is associated with better outcomes and a lower rate of progression to geographic atrophy.

Eyes with SRF present at baseline had a higher visual acuity improvement than eyes without baseline SRF up to 96 weeks in the Phase 3 VIEW trials of aflibercept (Eylea, Bayer/Regeneron) for nAMD.

 Irrespective of treatment frequency, presence of SRF shows a stable association with better visual outcomes in nAMD.

Further supporting evidence comes from theComparison of Age-related Macular Degeneration Treatments Trials (CATT) study, which showed that foveal IRF is associated with worse visual acuity at year 5 and eyes with foveal SRF had better visual acuity at this time point than eyes that did not.

In the FLUID study, vision outcomes with ‘intensive’ treatment aiming for complete fluid resolution were not significantly better than those seen with a ‘relaxed’ regimen that tolerated some SRF (≤200 µm only at the foveal centre).

Not all retinal fluid is the same, argued Dr Joan Miller, Harvard Medical School, United States, who spoke at the AAO 2019 Retina Subspecialty Day. While some SRF may be tolerated with ongoing treatment, IRF indicates CNV activity and needs to be treated more assertively, she said.

Anatomic improvements (in particular, resolution of IRF) are closely associated with better visual outcomes in nAMD. Clinical studies show that stable subfoveal SRF may be associated with better visual outcomes than persistent IRF.

Recent evaluations from the HARBOR study showed that those patients with residual SRF have the best vision outcomes, suggesting that a dry retina does not necessarily correlate with the best vision gains.17 In a post-hoc analysis of the VIEW trials, eyes with early, persistent IRF were shown to have significantly poorer visual acuity gains than those without residual IRF (Figure 1).

 Furthermore, IRF but not SRF was found to have a detrimental impact on visual acuity over 52 weeks.

In the HAWK and HARRIER studies, superior anatomic efficacy outcomes seen for brolucizumab (Beovu, Novartis) with respect to retinal thickness and fluid did not translate to superior vision gains over standard-of-care aflibercept.

Recommendations on the use of fluid status to guide treat-and-extend regimen decisions with anti-VEGF therapy for nAMD, from a global collaboration of expert ophthalmologists and retinal specialists who presented at the Europe Controversies in Ophthalmology 2020 Virtual Conference (COPHy) in March 2020, are summarised in Table 1. Whilst IRF can be considered a biomarker of disease activity, some persistent SRF may be tolerated. Moreover, improving IRF and/or stable SRF can be managed using maintained or extended treatment intervals.

Recent international ophthalmic congresses have featured advocates for and against the need for complete fluid resolution when treating nAMD, with some ophthalmologists arguing for a zero-tolerance approach to the presence of fluid, and others claiming some residual fluid can be tolerated and may be helpful in some patients. 