eLetters

123 e-Letters

published between 2018 and 2021

  • Presumptive JC viral retinitis

    Thank you for raising the issue of abbreviations entering the virological lexicon which might give rise to confusion and misunderstanding. Over a decade has elapsed since our patient report was published and the source material is not retrievable. However, our recollection is the patient was discussed contemporaneously at the MDT and the viral aetiology, radiology findings and medical management determined and documented, from which the data was sourced for the 2008 report. Plausible as it may seem, it is not possible to test the veracity of the suggestion that the names ‘Jamestown Canyon’ and ‘John Cunningham’ might have been transposed during that MDT many years after the event, paper records are not kept indefinitely in NHS practice and ethics in medical publishing demands that patient identifiers are not described or retained in order to preserve anonymity. Perhaps the latter should have been considered over half a century ago when JC virus was first identified in the brain of the unfortunate patient after whom the eponymous pathogen was christened
    (Padgett BL, Walker DL; et al. (1971). "Cultivation of papova-like virus from human brain with progressive multifocal leucoencephalopathy". Lancet. 1 (7712):
    1257–60. doi:10.1016/S0140-6736(71)91777-6)
     

  • Change in the ophthalmoscopical optic disc size and shape in a 10-year follow-up: a short comment

    I read with interest the article by Jonas et al 1. The main purpose of the authors was to explore associations between a disc size change and other morphological parameters. Indeed, many non-ophthalmic and game-changing parameters are associated with disc size change and other morphological parameters, such as the serum lipids 2 dietary factors (such as lutein, zeaxanthin, and omega-3 fatty acids) 2-4, medications (such as lipid-lowering agents) 2, genetic susceptibility, body mass index, age and sex 3, among which only age and sex are addressed in their retrospective analysis.

    According to the authors, decrease in the ophthalmoscopic disc size in the myopic eyes during the 10-year follow up, is likely related to a shift of the Bruch’s membrane opening as the inner of the three optic nerve head canal layers into the direction of the fovea. While their interpretations can be partly true, their attributed mechanism is subject to many biases.

    Firstly, changes in ophthalmoscopical optic disc size and Bruch’s membrane are a function of macular pigment optical density 5-7, which in turn is a function of dietary carotenoid intake 8;9. Tong et al 10 have shown before that macular pigment optical density (MPOD) is inversely associated with axial length in Chinese subjects with myopia, suggesting that carotenoid intake, particularly lutein, is associated to axial length as well. Another study with a smaller sample size (45 eyes of 32 patients) with a different mean a...

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  • Beware of abbreviations: John Cunningham (JC) versus Jamestown Canyon virus

    In their 2008 case report, Muqit, et al. describe a case of “presumptive Jamestown Canyon viral retinitis.”1

    Jamestown Canyon virus is a mosquito-borne, single-stranded, ribonucleic acid (RNA) orthobunyavirus that is endemic throughout much of North America.2,3 Infection with Jamestown Canyon virus may be asymptomatic or may result in a general febrile illness, meningitis, and/or meningoencephalitis.2,3 Beyond the above case report by Muqit, et al.,1 and another review article referencing this case report,4 Jamestown Canyon virus has not been reported to cause retinitis or other ocular manifestations.

    Upon close review of the case report by Muqit, et al.,1 we believe the authors are likely describing a case of John Cunningham (JC) virus (a ubiquitous, double-stranded, deoxyribonucleic acid [DNA] human polyomavirus known to cause progressive multifocal leukoencephalopathy [PML] among the immunocompromised)5-7 rather than Jamestown Canyon virus.

    First, the case patient with viral retinitis had underlying human immunodeficiency virus (HIV) infection and a low CD4 lymphocyte count (240 cells/mm3), making him immunocompromised and susceptible to reactivation of the John Cunningham (JC) virus. Second, the case patient had magnetic resonance imaging (MRI) brain findings (i.e., asymmetric, predominantly posterior, confluent, subcortical white matter hyperintensities involving U-fibers) that are classic for John Cunningham (JC) virus-related PML.6,7 In fact,...

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  • Comment on : Swept source optical coherence tomography angiography in patients treated with hydroxychloroquine: correlation with morphological and functional tests

    We read with great interest the article by Forte et al1, "Swept source optical Coherence tomography Angiography in patients treated with hydroxychloroquine: co-relation of the functional and morphological test." Hydroxychloroquine (HCQ) is a widely used drug for the management of systemic lupus erythematosus and rheumatoid arthritis. Non-invasive tests like optical coherence tomography, optical coherence tomography-angiography, 10-2 visual fields and multifocal ERG (mf-ERG) help in the early detection of the toxicity.2 We would like to highlight here importance of adaptive optics, and various studies done for the early detection of HCQ toxicity. In the study by Forte et al, mf-ERG did not co-relate with the flow changes on OCT-A, however in another observation by Penrose et al (n=6) a depression of signals on multifocal ERG was found in the perifoveal region even when the patients had normal visual acuity and a normal fundus.3Costa et al found significant differences between the micro-perimetry in the patients taking hydroxychloroquine and controls.4 It will be interesting to know the authors take on this. Besides these, adaptive optics is emerging as an important tool to detect the early photo-receptor changes in patients with HCQ toxicity. Adaptive optics help in the direct visualization of the cone mosaic. Stepien et al in their observation on 4 patients observed that adaptive optics showed a loss of cone mosaic in the perifoveal region that corresponded with...

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  • RE: Associations of ophthalmic and systemic conditions with incident dementia in the UK Biobank

    Shang et al. conducted a prospective study to examine the effect of ophthalmic and systemic conditions on incident dementia (1). The adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) of age-related macular degeneration (AMD), cataract, diabetes-related eye disease (DRED), and glaucoma at baseline for incident dementia were 1.26 (1.05 to 1.52), 1.11 (1.00 to 1.24), 1.61 (1.30 to 2.00), and 1.07 (0.92 to 1.25), respectively. Diabetes, heart disease, stroke and depression at baseline were also significantly associated with an increased risk of dementia. In addition, some combinations of ophthalmic and systemic conditions were at the higher risk for incident dementia. I have a comment about the study.

    Vision impairment is a risk factor of dementia, and poor vision is independently associated with a decline in cognitive function (2). Shang et al. clarified that AMD, cataract, and DRED were risk of incident dementia, and some combinations with systemic conditions accelerated risk of incident dementia. Although glaucoma was not significantly associated with increased risk of al-cause dementia, it was significantly associated with increased risk of vascular dementia. The authors also conducted analysis by excluding data in the first 5 years of follow-up, consistent results were also specified on the combined effects of ophthalmic and systemic conditions on incident dementia. Although the mechanism of increased risk of dementia in combinations with ophthalmic and...

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  • Goblet cells - sine qua non for conjunctival rehabilitation

    To the editor,

    We read with interest the recent publication by Bertolin et al. (“In vitro establishment, validation and characterisation of conjunctival epithelium outgrowth using tissue fragments and amniotic membrane”). Their validated conjunctival analogue of the simple limbal epithelial transplantation does represent a promising advance in the field. It is, however, interesting to note that the established tissue application was mainly validated on its growth potential and not specifically on its ability to reinstate a healthy ocular mucosal surface.

    Functional validation is of utmost importance, especially as the glued fragments are directly transplanted. This approach circumvents the need for expensive cell culture but also bypasses the stringent release criteria for cell therapies or tissue-engineered transplantation products. We would suggest that before this technique can be considered fully validated, it should be demonstrated that the obtained conjunctival cells contribute to the first line of mucosal defence, i.e. barrier formation. Several conjunctival barriers can be identified, such as intercellular junction complexes, glycocalyx and secreted mucins. Bertolin et al. demonstrated the presence of tight junctions (cfr. ZO-1 protein) and a glycocalyx (cfr. membrane-associated mucin-1), but failed to address the presence of goblet cells. As goblet cells are responsible for the secretion of mucin 5AC, which is the most abundant mucin in the mucin la...

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  • Is impaired cerebrospinal fluid dynamics the link between dementia and normal-tension glaucoma ?

    We like to congratulate Mullany et al. for their paper on normal-tension glaucoma is associated with cognitive impairment.1 To link normal-tension glaucoma (NTG) to cognitive impairment and therefore to a neurodegenerative process opens a new vista and research approach for glaucoma research. NTG indeed is an intriguing optic neuropathy that presents with a glaucomatous optic disc appearance and visual field loss similar to that seen in primary open angle glaucoma. The main risk factor for glaucoma however, increased intraocular pressure is missing.

    Unlike other cranial nerves the optic nerve is a white matter tract of the brain, enveloped in the meninges (dura, arachnoid and pia mater) and surrounded by cerebrospinal fluid (CSF) on its entire length. And CSF indeed may be the link that connects the neurodegenerative process leading to cognitive impairment and the glaucomatous optic neuropathy in NTG. Recent research demonstrated a relationship between decreased CSF flow, measured in the ventricles and the spinal cord, and cognitive deficit in the elderly.2 In NTG, impaired CSF dynamics was demonstrated with computer assisted cisternography in the subarachnoid space of the intraorbital optic nerve most pronounced in the bulbar region behind the eye globe.3 In a recent publication we found an elevated L-PGDS concentration in the subarachnoid space of the optic nerve in NTG patients with optic nerve sheath compartment syndrome that results in a reduced CSF turnover.4...

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  • Macular hole surgery should be prioritised, not delayed by observation.

    We would like to congratulate Uwaydat et al. on their large series of spontaneously closed macular holes (MH), which adds new information to the literature.(1) It reinforces the observation that traumatic MH can spontaneously close and that a period of observation in these eyes, where the results of surgery are not clear, is a worthwhile option. However, we disagree with their conclusion that eyes with recent onset small primary MHs should also be observed. The authors don’t suggest a time period for observation but found that the median time for closure for these small holes was 4.4 months.

    The report by Uwaydat et al. has 40 authors and the 60 cases of idiopathic MH were collected over at least a two-year period. Assuming a conservative number of 25 MH cases seen per surgeon per annum, this would give a spontaneous closure rate of ~3%, which is similar to the published literature as the authors review in their article.

    MH are known to enlarge with time, even in the short term. Madi et al, reported that 83% enlarged, by a median of 105 microns in 8 weeks. (2) Similarly, Berton et al recently estimated that holes less than 250 microns enlarge by a mean of 1.67 microns per day, resulting in a similar 100-micron increase in 2 months.(3)

    The anatomical and visual outcomes of surgery are dependent on MH diameter and duration. Holes greater than 300 microns, and with a duration more than four months are less likely to regain 0.3 logMAR or better.(4)...

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  • Extended Utility Domains for Health Economics Evaluations in Ophthalmology: A call to action

    Atik et al (BJOhttps://bjo.bmj.com/content/105/5/602) have done an excellent job of summarizing the current state of the art for conducting health economic evaluations in ophthalmology. Not surprisingly, however, such tools and techniques were originally designed to address broader questions of healthcare funding and resource allocation across many disparate clinical areas. As such, the general use case was very far removed from ophthalmology. This is relevant as a central component is the calculation of the utility parameters used, particularly in cost-effectiveness calculations (1). At present, the standard default utility measure remains the EQ5D, which does not prima facie include a vision specific domain (2). Rather, a “Vision Bolt-On” to the EQ5D which asks patients whether they “Have no problems seeing”; “Have some problem seeing”; or “Have extreme problems seeing” is proposed for increasing the precision of the utility score derived from patients for ophthalmic interventions (3). Unfortunately, the “Vision Bolt On” while theoretically increasing the discriminating power of the EQ-5D has not been widely adopted in economic evaluations conducted in ophthalmology (3-4). Moreover, as currently configured, the “Vision Bolt On” questions fail to adequately account for the clinical differences, say between central or fine reading vision which may be more relevant in patients with age-related macular degeneration, versus...

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  • Response to Martel et al. on visual hallucinations in sight loss

    Martel et al. report the prevalence, features and risk factors of visual hallucinations following eye removal (1). The findings indicate that visual hallucinations may be a significant and prevalent association of eye amputation, occurring in around one-third of cases. Throughout the paper, visual hallucinations are referred to as phantom visions, and categorised under the broad catchment of the phantom eye syndrome that includes pain and tactile sensations as well as visual hallucinations. Although the authors speculate phantom visions could be considered a subtype of Charles Bonnet syndrome (CBS) they are reluctant to refer to them as CBS, perhaps because of the longstanding debate as to whether CBS should be used to refer to a specific type of visual hallucination or a specific underlying cause (2,3). Where CBS is used to refer to a specific hallucination type, it is typically reserved for complex hallucinations and excludes the simple, ‘elementary’ hallucinations described as the most common experiences following enucleation. The consequence is that a range of terms have evolved to describe symptoms that have the same cause, adding confusion to the literature and hindering research and extensive efforts to raise awareness and establish appropriate patient management pathways for people with visual hallucinations (4-6).

    It is our opinion that both the simple and complex visual hallucinations described in the study should be referred to as Charles Bonnet syndrome....

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