eLetters

666 e-Letters

  • Letter to the Editor

    To the Editor,
    We read with great interest the article entitled “Central corneal basal cell density and nerve parameters in ocular surface disease and limbal stem cell deficiency: a review and meta-analysis”. In the analysis, the authors found a similar reduction of basal cell density (BCD) and corneal nerve parameters between the limbal stem cell deficiency (LSCD) group and the ocular surface disorders (OSD) group. However, several missteps in the study methods occurred.
    First, the analysis included ocular diseases that could lead to LSCD in the OSD group (eg, severe and chronic vernal and atopic keratoconjunctivitis, bullous keratopathy, and ocular graft-versus-host disease).[1] Second, acute microbial infectious keratitis, which is generally not considered as an OSD because of its distinct pathology, was included in the OSD group. Third, the severity of LSCD and OSD was not considered in the analysis. As previously demonstrated, the decrease in BCD and basal nerve density is positively correlated with LSCD severity.[2 3] Fourth, the overall sample size was very small. Lastly, no sensitivity/meta-regression analysis was done despite the significant heterogeneity in the OSD group.
    We repeated the analysis after removing 7 studies wrongly included into the OSD group (Al-Aqaba &al, Leonardi &al, Muller &al -2 reports-, Moein &al, Cavalcanti &al, Tepelus &al) and not including them in the LSCD group because of heterogeneity of the st...

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  • Optic nerve hypoplasia is associated with neurodevelopmental abnormalities requiring neuroimaging and paediatric review for improved diagnosis

    This is an informative article highlighting the difficulties in diagnosing optic nerve hypoplasia (ONH) in infants. Comparisons were made of the reliability of MRI orbit to that of fundal photography, with the authors concluding that the latter was superior to neuroimaging for diagnostic purposes. Whilst valid, this may imply that MRI brain scans are not indicated when a diagnosis of ONH is under consideration.

    ONH has an incidence of between 2-10.9 per 100,000 births, systemic associations include developmental delay and neurologic deficits in over 50% and endocrine dysfunction in just over one-quarter of patients.(1) Children may display midline structural defects (abnormalities of the septum pellucidum, corpus callosum and pituitary axis), in addition to other cortical abnormalities, thus requiring neuroimaging.(1,2) A diagnosis of septo-optic dysplasia becomes appropriate when two out of three features are present: ONH, midline abnormalities and pituitary insufficiency. As babies and infants with ONH present primarily with abnormal visual behaviour, nystagmus, strabismus or amblyopia, from as early as 3 months of age, the Ophthalmologist may be the first specialist to evaluate the patient, and so the importance of investigating the wider clinical and radiological features cannot be overstated. This was not mentioned in this paper by Kruglyakova et al.

    Whilst one can argue that a normal MRI brain scan in a child with ONH is not predictive of future end...

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  • Comment on: Detecting optic nerve head swelling on ultrasound and optical coherence tomography in children and young people.

    Optic disc drusen pose a diagnostic challenge when trying to differentiate between papilloedema and pseudopapilloedema.1 Dahlman-Noor et al highlight the importance of a structured history when evaluating children with optic nerve head (ONH) swelling. The authors recommend a future study to explore the diagnostic accuracy of an algorithm published by the Royal College of Paediatrics and Child Health (RCPCH) which details key features of the history (e.g. headache, vomiting, visual symptoms) that should trigger neuroimaging.2

    As part of a prospective study of children referred to our regional paediatric ophthalmology service for assessment for ONH swelling, we implemented this algorithm. 122 children under 16 years of age were assessed from 1st January to 31st December 2018. 93% (113/122) had optic disc drusen, 4% (5/122) had normal optic discs, and 3% (4/122) had papilloedema. Two cases of papilloedema were caused by idiopathic intracranial hypertension (IIH) and two by venous sinus thrombosis.

    Of the 118 patients with drusen or normal discs, only one fulfilled the RCPCH criteria for neuroimaging: a 14-year-old girl with persistent headaches and vomiting. Neuroimaging and lumbar puncture were unremarkable, and her symptoms were ultimately attributed to migraine.

    For the four patients with papilloedema, the algorithm-derived questions would have triggered neuroimaging in three cases. This yields a specificity of 99% but a sensitivity of only...

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  • Using the Duke Elder exam as a determinant of ophthalmic career interest

    We thank S N Gillan et al for their original study investigating the influence of medical student career aims on ophthalmic surgical simulator performance. The authors reported no association between medical student interest in pursuing an ophthalmic career and microsurgical task performance.

    The authors recruited subjects from the medical student division of the ‘Moorfields Academy’ and deemed these subjects as students with career interests in ophthalmology. However, we suggest that a more accurate measure in determining ophthalmic career interest would be whether these students had undertaken the ‘Duke Elder exam’, an annual national undergraduate prize examination in ophthalmology, and the only specialty-specific prize examination in the UK. We believe that undertaking the ‘Duke Elder exam’ and the preparation that this involves demonstrates commitment to the ophthalmic specialty more than being a member of the ‘Moorfields Academy’. Almost 30% of candidates ranked in the top 20 in this exam eventually pursue an ophthalmic career [1].

    Moreover, as the ‘Duke Elder exam’ can be taken multiple times during the course of a medical degree, it would have been particularly interesting to examine the correlation between the frequency that this exam had been taken with microsurgical task performance. However, we would also like to state that a proportion of the subjects in this study have likely undertaken the ‘Duke Elder exam’. Finally, using the ‘Duke Elder exam’...

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  • Going viral: mitigating risk in ophthalmology

    We read with interest the BMJ Editorial Novel Coronavirus disease 2019 (COVID-19): The importance of recognising possible early ocular manifestation and using protective eyewear1. This highlights the need for risk mitigation in the context of commonplace eye examinations using the slit-lamp biomicroscope and direct ophthalmoscope, both requiring very close proximity manoeuvres within a few centimetres of the patients’ eye, nose and mouth. Droplet spread during eye examination likely increases during these prolonged direct examination techniques. Those at most risk are trainees working in accident and emergency, opticians or acute care settings who are required to see patients presenting with “red eye” for which conjunctivitis is a common cause.

    Patients with conjunctivitis can be safely manged by the non-specialist using simple observation and history enquiry2 supplemented by a phone captured image. Remote-site consultation allows further discussion allowing an eye image and clinical details to be scrutinised without the requirement for on-site attendance. Currently, clinicians use mobile phone consultations to supplement and enhance care provision and it would seem prudent to adopt this more widely to minimise risk of Covid-19 transmission which might be acquired through public transport travel, waiting room exposure or face to face consultation. Notwithstanding confidentiality issues of commonly used freeware with private image messaging capabilities e.g Whatsap...

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  • Response to: ‘Utility of digitally assisted vitreoretinal surgery systems (DAVS) for high volume vitreoretinal surgery centres: a pilot study’.

    Dear Sir

    We read with interest Babu’s report on ‘Utility of digitally assisted vitreoretinal surgery systems (DAVS) for high volume vitreoretinal surgery centres: a pilot study’.1 As the first unit in the United Kingdom to purchase and use the NGENUITY 3D Visualization System (Alcon Laboratories, Fort Worth USA), we would like to share our experience. We assessed DAVS against analogue microscope (AM), from the Consultant surgeons’, trainees and the scrub nurses’ perspective. In our group there was a rapid adaption to the altered colours, head position and stereo vision offered by the DAVS for macular disease, with slower uptake for complex retinal detachments and trauma. In particular, we found the view and quality of image colour in macular cases to be sharp, even at high magnification, making for easier and safer membrane peels. DAVS provided a tangibly improved image quality and ease of description and teaching never previously experience by everyone present in theatre. Surgical trainees particularly benefited from better anatomical and a 3D view of the vitreoretinal pathology. Anecdotally, we tend to agree with Babu et al’s findings that the limitations lie in complex anterior segment cases, particularly with a poor red reflex, where we found the view of the posterior capsule to be compromised compared to the AM. Also, the presence of a sizeable disparity in contrast between immediately adjacent structures in the posterior segment (e.g. colobomas, asteroid hyal...

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  • Acellular nerve allografts are viable alternatives to nerve autografts in corneal neurotization

    There is no unified consensus in the peripheral nerve literature regarding the optimum type of interposition nerve graft for target tissue reinnervation. There are multiple well-designed peer reviewed studies by leading experts in peripheral nerve surgery supporting the use of acellular nerve allografts (ANAs) as viable alternatives to nerve autografts at various gap lengths [1-3]. While there are no trials directly comparing the use of ANAs to nerve autografts in corneal neurotization, Avance® allografts have now become “on label” for corneal neurotization given the successful clinical outcomes reported by several tertiary care centers [4].

    In comparing the study by Catapano et al. to the study by Leyngold et al. it is important to note that the average follow up in the former was 24 months whereas it was only 6 months in the latter [4,5]. In addition, 88% of the patients in the paper by Catapano et al. were under 18 years of age vs. 14% in the paper by Leyngold et al. As stated in my previous correspondence, Park et al has shown that pediatric age is correlated to improved results in corneal neurotization irrespective of the technique [6]. Catapano et al. noted continued improvement in central corneal sensation (CCS) up to two years postoperatively. The reported CCS at 6 months postoperatively was only 30.0±26.8mm with a significant number (44%) of patients in their study having CCS at or below 10mm and peripheral corneal sensation (PCS) at or below 30mm at that...

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  • OPHTHALMOLOGISTS IN THE FRONT LINE OF THE WUHAN VIRUS

    It has been seventeen years since the emergence of Severe Acute Respiratory Syndrome (SARS -CoV)1 and in 2004, we reported the presence of SARS-CoV in human tears and highlighted the possibility of human transmission through tears2.

    A new strain of coronavirus (2019-nCoV) has emerged recently in China.3 A recent report highlighted the possibility of transmission through tears.4 This thus serves as a timely reminder for ophthalmologists and healthcare professionals to take necessary precautions in the clinic. Furthermore, asymptomatic patients are potentially infective.3

    As ophthalmologists, we sit eye-to-eye with our patients and this close proximity puts us at high risk of being exposed to such infections. When measuring intraocular pressure under topical anaesthesia, our fingers are in contact with the periocular skin or fluorescein-stained tears and it is conceivable that poor hand hygiene increases risk of disease transmission. The tips of reusable bottles of anaesthesia may also come into contact with tear fluid or eyelashes of patients at risk. Also, the use of Schirmer’s test for dry eyes or research purposes, might be sources of infection if the tear samples are not stored properly. It is thus important to ensure good hand hygiene, to wear surgical masks, and if handling infected patients, to don personal protective equipment (PPE) and goggles. It is also important to ensure proper disinfection of reusable equipment (such as tonometer tips). Alternat...

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  • Clinical Evidence Points to a Higher Risk of Procedural Failure with Acellular Nerve Allograft Use in Corneal Neurotisation

    Dr. Leyngold states we ‘fail to support [our] viewpoint with peer reviewed studies.’ Our position against the use of acellular nerve allografts (ANAs) in corneal neurotisation was grounded on robust evidence from basic science literature demonstrating their inferior performance relative to autografts for large gap nerve repair. No clinical trial comparing the two techniques exists, and in our opinion there lacks the necessary equipoise to perform such a study.

    The regeneration-restrictive properties of long-segment ANAs renders them unsuitable for use in directing sensory axons to the cornea. The largest single-centre study on Avance® ANA use for peripheral nerve repair demonstrated meaningful recovery in only 54% of cases where allografts longer than 50 mm were employed [1]. Remarkably, exploitation of the suboptimal capacity of ANAs to support nerve regeneration has been proposed as a means to inhibit axon growth in the surgical management of painful neuromas [2].

    In his defence of off-label use of Avance® allografts in corneal neurotisation, Dr. Leyngold cites his case-series wherein sensory improvement of 35 mm or more was documented in two of seven eyes (29%). In contrast, Catapano et al. noted sensory improvement of 35 mm or more in 16 of 18 cases (89%) where nerve autografts were employed to route healthy trigeminal sensory axons to anaesthetic corneas [3]. In our own experience, we have yet to encounter a suboptimal neurotization outcome with use of n...

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  • Combined subconjunctival injection of dexamethasone for the management of acute primary angle closure: a randomised controlled trial

    The authors would like to thank Dr. MAYURI BORGOHAIN et al. for their interest on our study ‘Combined subconjunctival injection of dexamethasone for the management of acute primary angle closure: a randomised controlled trial’, and appreciate their insightful comments.
    First, in this study, for “Combined Subconjunctival Injection of Dexamethasone”, we means combination subconjunctival injection of Dexamethasone with anti-glaucoma drug (such as topical pilocarpine, beta-blocker, brinzolamide, and alpha-2 agonists).
    Second, for better investigating the effectiveness of injection of dexamethasone, the control group was designed to not subjected to any topical anti-inflammatory drug. Moreover, Patients that were excluded with a usage of topical anti-inflammatory drugs (including NASIDs and steroids), which was mentioned in the method part.
    Third, the range of intraocular pressure (IOP) in those 42 eyes was 27-60 mmHg.
    Fourth, to study the window period from onset of acute attack for maximum efficacy of subconjunctival dexamethasone injection, we performed correlation analysis between the duration before recruitment with the decrease of IOP (IOPbaseline – IOP24h),and found that the decrease of IOP was corelated with the duration before recruitment (r = -0.481, p = 0.002). Moreover, about one half of patients that the duration less than 5 days had more efficacy of subconjunctival dexamethasone injection.

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