eLetters

100 e-Letters

published between 2017 and 2020

  • 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.

  • Efficacy of acellular nerve allografts in corneal neurotisation: an objective evaluation of the existing evidence

    Given the lack of level 1 evidence there is no unified consensus among peripheral nerve experts on the optimum type of interposition nerve graft for target tissue reinnervation. There are multiple peer reviewed studies by leading experts in peripheral nerve surgery supporting the use of acellular nerve allografts (ANAs) as viable alternatives for peripheral nerve reconstruction at various gap lengths [1-3]. Moreover, as the authors correctly point out in their correspondence, no trials exist comparing the use of ANAs to nerve autografts in corneal neurotization, nullifying their claim of nerve autograft superiority for this procedure. Of note, Avance® allografts have become “on label” for corneal neurotization since my last correspondence.

    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. 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. Catapano et al reported mean CCS at 30.0±26.8mm at 6 months postoperatively, with a significant number (44%) of patients in their study having CCS at or below 10...

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

    To,
    The editor
    We would like to congratulate Huang et al. for their study ‘Combined subconjunctival injection of dexamethasone for the management of acute primary angle closure: a randomised controlled trial’.1 However, we have few queries and seek your kind attention.
    First, as mentioned in this article, a previous study in dogs showed combination of topical anti-inflammatory eye drops was beneficial during treatment.2They had conducted this present study as there was no data on humans regarding a randomised controlled trial that demonstrates the effectiveness of anti-inflammatory drugs for the treatment of human eyes suffering from acute primary angle closure (APAC). However, as the title suggested combination of subconjunctival dexamethasone injection, it implied combination of it with other anti-inflammatory drugs. However, the injection group was not subjected to any other anti-inflammatory drugs.
    Second, the authors’ previous study showed that the inflammatory response in the aqueous humor from APAC patient was evident and that multiple inflammatory factors were elevated significantly.3 Topical steroids help to reduce intraocular inflammation make the patient more comfortable.4 However; the control group was not subjected to any topical anti-inflammatory drug.
    Third, we are interested to know about the range of intraocular pressure (IOP) in those 42 eyes; the highest and lowest IOP recorded.
    Fourth, we are also interested to know r...

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  • Dilemma of Ultra-low dose vs Low-dose Radiation Therapy for Ocular Adnexal Lymphomas: The prospective trial has been underway

    To the Editor:
    We herein respond to the letter written by Camus et al raising the issue of “ultra-low” dose radiation therapy (4 Gy) vs. the “standard low-dose” radiation therapy (24-30 Gy) for lymphomas of the orbit, eyelid, and conjunctiva, also referred to as “ocular adnexal lymphoma” (OAL). First off, it is important to point out that the goals of the retrospective multicenter general review of marginal zone lymphoma coordinated by Professor Steffen Heegaard in Denmark which also included some of our patients from M. D. Anderson was not to compare the efficacy of various treatment strategies.(1) Indeed it is challenging to draw practice altering conclusions from a retrospective multi-center study given the usual limitations, most notably the variation in staging and treatment approaches across various continents as noted by Camus et al.

    However, we agree with Camus et al that our encouraging preliminary observations in 22 patients with OAL treated with ultra-low dose radiation therapy (4Gy) suggested a very good response rate (100% ORR:86% CR, 14%% PR) for B-cell orbital and ocular adnexal lymphomas;(2) as such we started a prospective trial of ultra-low dose radiation for ocular adnexal lymphoma patients at MD Anderson Cancer Center soon thereafter (Clinicaltrials.gov identifier NCT02494700)The study aims to evaluate the efficacy of response adapted radiation therapy for this patient population, whereby all patients are treated to an initial 4 Gy in...

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  • Confounding effect of anterior chamber depth on assessment of dynamic air-puff applanation results in glaucoma patients

    We read the study by Vinciguerra et al. on cornea biomechanical properties of open angle glaucoma, ocular hypertension, normal tension and normal eyes assessed with dynamic air-puff applanation [1]. The study reported significant correlations between the properties and types of glaucoma. Most of the study patients were also under anti-glaucoma medication. Interestingly, the study did not assess the potential confounding effects of the anterior chamber on assessment of corneal biomechanical properties [1]. However, we wish to bring to the notice of the authors our earlier study on the same subject [2]. In our study, open and closed angle patients under the anti-glaucoma medication were assessed with air-puff applanation to determine if medication altered corneal biomechanical properties. The highlight of the study was that anterior chamber depth (ACD) was also included as a covariate in addition to other tomographic features [2]. Our study clearly showed that the ACD had a significant effect of the level of bIOP among the different types of glaucoma patient [2]. The ACD is a direct indicator of the volume of vault space between the cornea and the lens. This vault space resisted the inward motion of the cornea during the first half of the applanation. If ACD was lower, then bIOP was greater and vice versa. In patients with angle closure glaucoma, we expect the ACD to be less than NTG and normal eyes [1,2]. Hence, the results from the Vinciguerra et al. study could be skewed...

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  • Intraocular pressure change during reading or writing on smartphones in patients with normal-tension glaucoma

    To,
    The editor
    We would like to congratulate and highly appreciate Ha et al. for this simple and innovative study on ‘Changes in intraocular pressure during reading or writing on smartphones in patients with normal tension glaucoma’. However, we have few queries and seek your kind attention.
    First, out of 38 trabeculectomised eyes, 12 were not using any anti-glaucoma medications whereas remaining was on some antiglaucoma medications. An overall analysis was done including all trabeculectomised eyes. However, we think, it would have been better analyzed if the authors had compared eyes with or without antiglaucoma medications separately. We are interested to know the pattern of intraocular pressure (IOP) fluctuation in eyes with trabeculectomy not using any antiglaucoma medications.
    Second, in this present study, no control group was included.
    Third, it was established that there is circadian pattern of IOP change in normal tension glaucoma patients. Therefore, we are interested to know whether IOP was measured in all patients at the same time of day or was it measured at different times of the day.

    References
    1. Ha A, Kim Y K, Kim J et al. Changes in intraocular pressure during reading or writing on smartphones in patients with normal-tension glaucoma. Br J Ophthalmol. 2019; Sep314467doi.org/10.1136/bjophthalmol-2019-314467
    2. Lee Y R, Kook M S, Joe S G et al. Circadian (24- hour) pattern of intraocular pressure and visual...

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  • Response to eLetter: The Estimated Number of Ophthalmologists Worldwide (International Council of Ophthalmology Update): Will We Meet the Needs?

    We appreciate the comment provided by Dr. Martins regarding our recent estimates of the global number of ophthalmologists, and we agree wholeheartedly with his points, which are encapsulate in the conclusion of our article.1 We appreciate the opportunity to further elaborate.
    Although the global ophthalmologist workforce appears to be continuously growing, our most important finding is that the numbers alone are not sufficient to ensure universal eye health coverage, with no relationship observed between national prevalence of blindness and ophthalmologist density.1 We believe the appropriate distribution, and deployment of ophthalmologist and eye care teams, combined with outreach services where appropriate are important solutions to increasing access of eye care among remote populations. However, we especially stress that the integration of comprehensive eye care into the health care system is critical to universal eye health coverage.2 We emphasize the need for different models of care and service-delivery and the role of the eye care professional cadres, including optometrists and allied ophthalmic personnel, particularly in task-shifting refraction and basic eye care services.
    Comprehensive eye care begins at the primary care level,2 and we agree that more ophthalmology education is needed as part of medical education. If primary care providers are able to provide basic eye care services at the community level, then it is assumed that task-shifting of the...

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