689 e-Letters

  • Keratoconus in Down syndrome: A diagnostic dilemma

    The recent study by Vega-Estrada et al highlights some of the challenges in diagnosing keratoconus in Down syndrome (DS).[1] Previous studies have shown that the cornea of individuals with DS without evidence of keratoconus appear to be steeper and thinner than the general population, both being features characteristic of keratoconus.[2] Vega-Estrada et al further identified that posterior keratometry was similar in DS to mild keratoconus, however, a lesser degree of posterior elevation was observed in the DS group.[1] This may be related to the younger mean age of the cohort with DS, small sample size or diagnostic criteria. The authors concluded that the corneal features analysed in the DS cohort were in the range of normal to mild keratoconus.[1]

    We would like to further highlight some of the challenges associated with image acquisition when performing corneal topo/tomography in patients with DS. Some of the ophthalmic manifestations such as slanted and small palpebral apertures, nystagmus and strabismus can affect fixation. We have also observed additional common behavioural responses that affect fixation and alignment; patients squeezing the eyes shut in response to the examiner touching the eyelids or involuntarily opening the mouth when asked to keep the eyes wide open.

    Misaligned fixation while acquiring corneal tomography images is known to result in false keratoconus features.[3] In addition to the reported overlap in corneal features in DS and ke...

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  • Repeatability of automated leakage quantification and microaneurysm identification ‎utilising an analysis platform for ultra-widefield fluorescein angiography. Avoid ‎misinterpretation

    Applying Pearson r to assesses the repeatability of a test is a methodologic mistake which leads to ‎misinterpretation.‎

    Repeatability of automated leakage quantification and microaneurysm identification ‎utilising an analysis platform for ultra-widefield fluorescein angiography. Avoid ‎misinterpretation
    Dear editor, We were interested to read the paper by Jiang A et al. published in Apr 2020 edition of the ‎Br J Ophthalmol.1 Ultra-wide field fluorescein angiography (UWFA) provides unique opportunities for ‎panretinal assessment of retinal diseases. The objective quantification of UWFA features is a labour-intensive ‎manual process, limiting its utility. The authors aimed to assesses the consistency/repeatability of an automated ‎assessment platform for the characterization of retinal vascular features, quantification of microaneurysms (MA) ‎and leakage foci in UWFA images. For each eye, two arteriovenous-phase images and two late-phase images ‎were selected. Automated assessment was performed for retinal vascular features, MA identification and ‎leakage segmentation. Panretinal and zonal assessment of metrics was performed. The authors mentioned a ‎significant correlation between paired time points for retinal vessel area and vessel length on early images ‎‎(Pearson r=0.92, p<0.0001; Pearson r=0.94, p<0.0001) and late images (Pearson r=0.92, p<0.0001; Pearson ‎r=0.92, p<0.0001, respectively). Panretinal and zonal MA counts demonst...

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  • Comment on Ocular manifestations of a hospitalised patient with confirmed 2019 novel coronavirus disease

    At the outset, we would like to congratulate the authors for determining the presence of the viral RNA over time in conjunctival specimens of a patient with COVID-19, which was much needed.
    The clinical course of viral conjunctivitis is self-limiting. Usually only supportive treatments like cold compress, artificial tears and topical steroids are given. The time duration taken for symptoms to subside without treatment ranges from 4-6 days to 2-3 weeks, depending upon the type of disease.[1] Clinical studies regarding the usage of antivirals for conjunctivitis reveal that they were effective only for DNA viruses and was not free of toxicity.[2]
    In the case report regarding ocular manifestation of patient with 2019 novel corona virus disease,[3] the ocular symptoms of patient resolved after 5 days of its onset and the author claims it to be possibly due to treatment with ribavirin eye drops. As Corona virus is a RNA virus, we believe that antiviral therapy would have been limited use. Adequate corneal tissue levels of antiviral agents are achieved by both topical and systemic administration.[4] If antiviral therapy was the reason for improvement of ocular symptoms, the patient was on three oral antiviral drugs (Umifenovir, lopinavir and ritonavir) in addition to topical ribavirin. Therefore, attributing only topical ribavirin for curing ocular symptoms may not be appropriate with the limited evidence.
    The authors also had mentioned that sterile synthetic f...

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  • 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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